Perpendicular magnetic recording medium | Patent Publication Number 20020182445

US 20020182445 A1
Patent NumberUS 07090934 B2
Application Number10141446
Filled DateMay 8, 2002
Priority DateAug 3, 1999
Publication DateDec 5, 2002
Original AssigneeHoya Corporation
Current AssigneeWd Media Singapore Western Digital
Inventor/ApplicantsHirotaka Hokkyo
Shinzo Tsuboi
Katsumichi Tagami
Hirotaka Hokkyo
Katsumichi Tagami
Shinzo Tsuboi
International
1
G11B
National
2
428/694.0TM
428/827
Field of Search
0
The present invention provides a perpendicular magnetic recording medium 11 having a perpendicular magnetization film 22 formed on a substrate 20, wherein a high perpendicular orientation film 24 having higher perpendicular orientation than that of the perpendicular magnetization film 22 is formed over or/and under the perpendicular magnetization film 22.
Patent Claims data is locked.
Login To View
Module Locked
Module Locked
BACKGROUND OF THE INVENTION 0001 1. Field of the Invention 0002 The present invention relates to a perpendicular magnetic recording medium used as a magnetic disc. 0003 2. Description of the Related Art 0004 Recently, with progress of personal computers and work stations, the hard disc has been required to have a large capacity and small size, i.e., a high density. However, in order to realize a high recording density in the conventional longitudinal direction recording method, there are various problems. For example, if the recording bit is made smaller, there arises a problem of thermal fluctuation of recording magnetization and a problem of high coercive force which may exceed the recording capability of the recording head. To cope with this, a perpendicular magnetic recording method has been studied as means to significantly increase the recording density. 0005 FIG. 156 is a cross sectional view of such a conventional magnetic recording medium. In this perpendicular magnetic recording medium 50, a perpendicular magnetization film 54 having a perpendicular magnetic anisotropy is formed on a substrate 56. For example, CoCr alloys are used for the perpendicular magnetization film (Journal of Magn. Soc. Japan, Vol. 8, No. 1, 1984, pp.17-22). 0006 However, in such a conventional perpendicular magnetic recording medium, there has been a problem that medium noise characteristic is very bad in a low recording density region. This is because the perpendicular magnetization film 54 is magnetized perpendicularly, and a demagnetizing field caused by the magnetic poles generated on the medium surface generates a reversed-magnetic domain. The lower is the recording density, the more the reversed-magnetic domains are generated. This has been the main cause to deteriorate the medium noise characteristic in the low recording density region. This medium noise increase in the low recording density region becomes a big trouble when forming a high-density information recording apparatus. 0007 In order to reduce the effect of the demagnetizing field generated by the magnetic pole generated on the medium surface, there has been suggested to provide a soft magnetic layer under the perpendicular magnetization film so as to reduce the magnetic poles generated at the boundary between the perpendicular magnetization film and the soft magnetic layer (Japanese Patent Publication (examined) B58-91). This is generally known as a perpendicular two-layered magnetic recording medium. 0008 However, in this two-layered perpendicular magnetic recording medium, if a perpendicular magnetization film is provided on a soft magnetic layer such as NiFe (Permalloy), there arises a problem that the soft magnetic layer generates a spike-shaped noise, disabling to obtain a preferable medium S/N ratio. 0009 To cope with this, Japanese Patent Publication (unexamined) A59-127235, Japanese Patent Publication (unexamined) A59-191130, Japanese Patent Publication (unexamined) A60-239916, Japanese Patent Publication (unexamined) A61-8719, and Japanese Patent Publication (unexamined) A1-173312 suggest use of a perpendicular magnetization film on a backing layer made from Co or a Co alloy which is more advantageous than use of the permalloy soft magnetic layer. 0010 However, the inventor of the present invention has found that when these soft magnetic films are used, these films easily absorb an external magnetic field generated by a magnetic disc rotation spindle motor. This results in concentration of the magnetic flux in a magnetic head and losing of recording signals. That is, the perpendicular magnetic recording medium of the two-layered film configuration can reduce the effect of the demagnetizing field caused by the magnetic poles generated on the medium surface, but this cannot be a solution for medium noise reduction.
SUMMARY OF THE INVENTION 0011 It is therefore an object of the present invention to provide a perpendicular magnetic recording medium having a reduced effect of the demagnetizing field caused by a magnetic poles generated on a perpendicular magnetization film surface and having a preferable medium noise characteristic in a low recording density region. 0012 The perpendicular magnetic recording medium according to the present invention has a perpendicular magnetization film formed on a substrate, wherein a high perpendicular orientation film having higher perpendicular orientation than the perpendicular magnetization film is formed over or/and under the perpendicular magnetization film. 0013 A backing soft magnetic film may be formed under the high perpendicular orientation film, or under the perpendicular magnetic film if there is no high perpendicular orientation film under the perpendicular magnetization film. 0014 It is preferable that the high perpendicular orientation film have a perpendicular magnetic anisotropic energy Ku erg/cc and a saturation magnetization Ms emu/cc which are in the relationship R defined as 2Ku/4Ms2 equal to or greater than () 1.4. 0015 Moreover, it is preferable that the high perpendicular orientation film have a greater perpendicular magnetic anisotropic energy than that of the perpendicular magnetization film. The perpendicular magnetic anisotropic energy of the high perpendicular orientation film is preferably equal to or greater than 1106 erg/cc, and more preferably equal to or greater than 2107 erg/cc. The high perpendicular orientation film preferably has a thickness equal to or greater than 50 nm0016 The high perpendicular orientation film is preferably made from: a CoCrM alloy (wherein M represent three elements selected from a group consisting of Pt, Ta, La, Lu, Pr, and Sr); an alloy containing RCo5 (RY, Ce, Sm, La, Pr) as a main content; an alloy containing R2Co17 (RY, Ce, Sm, La, Pr) as a main content; Ba ferrite (BaFe12O19 BaFe18O27 and the like); Sr ferrite (SrFe12O19, SrFe18O27 and the like), PtCo, and the like. 0017 The backing soft magnetic film is preferably made from FeSiAl, FesiAl alloy, FeTaN, FeTaN alloy, and the like. 0018 In the perpendicular magnetic recording medium according to the present invention, the perpendicular magnetization film on its upper surface or lower surface a high perpendicular orientation film having a higher perpendicular orientation than that of the perpendicular magnetization film. Accordingly, it is possible to significantly suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0019 When the high perpendicular orientation film is made from a CoCr alloy, it is preferable that the perpendicular magnetic anisotropic energy Ku erg/cc and the saturation magnetization Ms emu/cc be in the relationship as R2Ku/4Ms2 wherein R1.4. 0020 On the other hand, when the high perpendicular orientation film is made from a SmCo alloy (i.e., a material other than the Cocr alloy), it is preferable that the high perpendicular orientation film have a perpendicular magnetic anisotropic energy Ku greater than that of the perpendicular magnetization film. This enables to reduce generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film.
BRIEF DESCRIPTION OF THE DRAWINGS 0021 FIG. 1 is a cross sectional view of a perpendicular magnetic recording medium according to a first embodiment of the present invention. 0022 FIG. 2 is a cross sectional view of a perpendicular magnetic recording medium according to a second embodiment of the present invention. 0023 FIG. 3 is a cross sectional view of a perpendicular magnetic recording medium according to a third embodiment of the present invention. 0024 FIG. 4 is a cross sectional view of a perpendicular magnetic recording medium according to a fourth embodiment of the present invention. 0025 FIG. 5 is a cross sectional view of a perpendicular magnetic recording medium according to a fifth embodiment of the present invention. 0026 FIG. 6 is a cross sectional view of a perpendicular magnetic recording medium according to a sixth embodiment of the present invention. 0027 FIG. 7 is a table showing values of perpendicular magnetic anisotropic energy Ku and saturation magnetization Ms for each of the Examples of the present invention. 0028 FIG. 8 is a graph showing medium noise dependency on the recording density in Example 1 of the present invention. 0029 FIG. 9 is a table showing relationships between the film thickness and the medium noise in Example 1 of the present invention. 0030 FIG. 10 is another table showing relationships between the film thickness and the medium noise in the Example 1 of the present invention. 0031 FIG. 11 is still another table showing relationship between the film thickness and the medium noise in the Example 1 of the present invention. 0032 FIG. 12 is yet another table showing relationships between the film thickness and the medium noise in the Example 1 of the present invention. 0033 FIG. 13 is still yet another table showing relationships between the film thickness and the medium noise in the Example 1 of the present invention. 0034 FIG. 14 is a table showing values of the perpendicular magnetic anisotropic energy Ku and saturation magnetization Ms for the respective Examples of the present invention. 0035 FIG. 15 is a graph showing the medium noise dependency on the recording density in Example 2 of the present invention. 0036 FIG. 16 is another table showing the relationship between the film thickness and the medium noise in Example 2 of the present invention. 0037 FIG. 17 is still another table showing the relationship between the film thickness and the medium noise in Example 2 of the present invention. 0038 FIG. 18 is yet another table showing the relationship between the film thickness and the medium noise in Example 2 of the present invention. 0039 FIG. 19 is still yet another table showing the relationship between the film thickness and the medium noise in Example 2 of the present invention. 0040 FIG. 20 is yet another table showing the relationship between the film thickness and the medium noise in Example 2 of the present invention. 0041 FIG. 21 is a table showing values of the perpendicular magnetic anisotropic energy Ku and saturation magnetization Ms for the respective Examples of the present invention. 0042 FIG. 22 is a graph showing the medium noise dependency on the recording density in Example 3 of the present invention. 0043 FIG. 23 is a table showing the relationship between the film thickness and the medium noise in Example 3 of the present invention. 0044 FIG. 24 is another table showing the relationship between the film thickness and the medium noise in Example 3 of the present invention. 0045 FIG. 25 is still another table showing the relationship between the film thickness and the medium noise in Example 3 of the present invention. 0046 FIG. 26 is yet another table showing the relationship between the film thickness and the medium noise in Example 3 of the present invention. 0047 FIG. 27 is still yet another table showing the relationship between the film thickness and the medium noise in Example 3 of the present invention. 0048 FIG. 2B is a table showing values of the perpendicular magnetic anisotropic energy Ku and saturation magnetization Ms for the respective Examples of the present invention. 0049 FIG. 29 is a graph showing the medium noise dependency on the recording density in Example 4-1 of the present invention. 0050 FIG. 30 is a table showing the relationship between the film thickness and the medium noise in Example 4-1 of the present invention. 0051 FIG. 31 is another table showing the relationship between the film thickness and the medium noise in Example 4-1 of the present invention. 0052 FIG. 32 is still another table showing the relationship between the film thickness and the medium noise in Example 4-1 of the present invention. 0053 FIG. 33 is yet another table showing the relationship between the film thickness and the medium noise in Example 4-1 of the present invention. 0054 FIG. 34 is still yet another table showing the relationship between the film thickness and the medium noise in Example 4-1 of the present invention. 0055 FIG. 35 is a table showing values of the perpendicular magnetic anisotropic energy Ku and saturation magnetization Ms for the respective Examples of the present invention. 0056 FIG. 36 is a graph showing the medium noise dependency on the recording density in Example 4-2 of the present invention. 0057 FIG. 37 is a table showing the relationship between the film thickness and the medium noise in Example 4-2 of the present invention. 0058 FIG. 38 is another table showing the relationship between the film thickness and the medium noise in Example 4-2 of the present invention. 0059 FIG. 39 is still another table showing the relationship between the film thickness and the medium noise in Example 4-2 of the present invention. 0060 FIG. 40 is yet another table showing the relationship between the film thickness and the medium noise in Example 4-2 of the present invention. 0061 FIG. 41 is still yet another table showing the relationship between the film thickness and the medium noise in Example 4-2 of the present invention. 0062 FIG. 42 is a graph showing the medium noise dependency on the recording density in Example 5 of the present invention. 0063 FIG. 43 is a table showing the relationship between the film thickness and the medium noise in Example 5 of the present invention. 0064 FIG. 44 is a table showing the relationship between the film thickness and the medium noise in Example 5 of the present invention. 0065 FIG. 45 is another table showing the relationship between the film thickness and the medium noise in Example 5 of the present invention. 0066 FIG. 46 is still another table showing the relationship between the film thickness and the medium noise in Example 5 of the present invention. 0067 FIG. 47 is yet another table showing the relationship between the film thickness and the medium noise in Example 5 of the present invention. 0068 FIG. 48 is a graph showing the medium noise dependency on the recording density in Example 6 of the present invention. 0069 FIG. 49 is a table showing the relationship between the film thickness and the medium noise in Example 6 of the present invention. 0070 FIG. 50 is another table showing the relationship between the film thickness and the medium noise in Example 6 of the present invention. 0071 FIG. 51 is still another table showing the relationship between the film thickness and the medium noise in Example 6 of the present invention. 0072 FIG. 52 is yet another table showing the relationship between the film thickness and the medium noise in Example 6 of the present invention. 0073 FIG. 53 is still yet another table showing the relationship between the film thickness and the medium noise in Example 6 of the present invention. 0074 FIG. 54 is a graph showing the medium noise dependency on the recording density in Example 7 of the present invention. 0075 FIG. 55 is a table showing the relationship between the film thickness and the medium noise in Example 7 of the present invention. 0076 FIG. 56 another table showing the relationship between the film thickness and the medium noise in Example 7 of the present invention. 0077 FIG. 57 is still another table showing the relationship between the film thickness and the medium noise in Example 7 of the present invention. 0078 FIG. 58 is yet another table showing the relationship between the film thickness and the medium noise in Example 7 of the present invention. 0079 FIG. 59 is yet still another table showing the relationship between the film thickness and the medium noise in Example 7 of the present invention. 0080 FIG. 60 is a graph showing the medium noise dependency on the recording density in Example 8-1 of the present invention. 0081 FIG. 61 is a table showing the relationship between the film thickness and the medium noise in Example 8-1 of the present invention 0082 FIG. 62 is another table showing the relationship between the film thickness and the medium noise in Example 8-1 of the present invention. 0083 FIG. 63 is yet another table showing the relationship between the film thickness and the medium noise in Example 8-1 of the present invention. 0084 FIG. 64 is still another table showing the relationship between the film thickness and the medium noise in Example 8-1 of the present invention. 0085 FIG. 65 is yet still another table showing the relationship between the film thickness and the medium noise in Example 8-1 of the present invention. 0086 FIG. 66 is a graph showing the medium noise dependency on the recording density in Example 8-2 of the present invention. 0087 FIG. 67 is a table showing the relationship between the film thickness and the medium noise in Example 8-2 of the present invention. 0088 FIG. 68 is another table showing the relationship between the film thickness and the medium noise in Example 8-2 of the present invention. 0089 FIG. 69 is yet another table showing the relationship between the film thickness and the medium noise in Example 8-2 of the present invention. 0090 FIG. 70 is still another table showing the relationship between the film thickness and the medium noise in Example 8-2 of the present invention. 0091 FIG. 71 is yet still another table showing the relationship between the film thickness and the medium noise in Example 8-2 of the present invention. 0092 FIG. 72 is a graph showing the medium noise dependency on the recording density in Example 9 of the present invention. 0093 FIG. 73 is a table showing the relationship between the film thickness and the medium noise in Example 9 of the present invention. 0094 FIG. 74 is another table showing the relationship between the film thickness and the medium noise in Example 9 of the present invention. 0095 FIG. 75 is yet another table showing the relationship between the film thickness and the medium noise in Example 9 of the present invention. 0096 FIG. 76 is still another table showing the relationship between the film thickness and the medium noise in Example 9 of the present invention. 0097 FIG. 77 is yet still another table showing the relationship between the film thickness and the medium noise in Example 9 of the present invention. 0098 FIG. 78 is a graph showing the medium noise dependency on the recording density in Example 10-1 of the present invention. 0099 FIG. 79 is a table showing the relationship between the-film thickness and the medium noise in Example 10-1 of the present invention. 0100 FIG. 80 is another table showing the relationship between the film thickness and the medium noise in Example 10-1 of the present invention. 0101 FIG. 81 is yet another table showing the relationship between the film thickness and the medium noise in Example 10-1 of the present invention. 0102 FIG. 82 is still another table showing the relationship between the film thickness and the medium noise in Example 10-1 of the present invention. 0103 FIG. 83 is yet still another table showing the relationship between the film thickness and the medium noise in Example 10-1 of the present invention. 0104 FIG. 84 is a graph showing the medium noise dependency on the recording density in Example 10-2 of the present invention. 0105 FIG. 85 is a table showing the relationship between the film thickness and the medium noise in Example 10-2 of the present invention. 0106 FIG. 86 is another table showing the relationship between the film thickness and the medium noise in Example 10-2 of the present invention. 0107 FIG. 87 is yet another table showing the relationship between the film thickness and the medium noise in Example 10-2 of the present invention. 0108 FIG. 88 is still another table showing the relationship between the film thickness and the medium noise in Example 10-2 of the present invention. 0109 FIG. 89 is yet still another table showing the relationship between the film thickness and the medium noise in Example 10-2 of the present invention. 0110 FIG. 90 is a table showing values of the perpendicular magnetic anisotropic energy Ku of the respective Examples of the present invention. 0111 FIG. 91 is a graph showing the medium noise dependency on the recording density in Example 11 of the present invention. 0112 FIG. 92 is a table showing the relationship between the film thickness and the medium noise in Example 11 of the present invention. 0113 FIG. 93 is a graph showing the medium noise dependency on the recording density in Example 12 of the present invention. 0114 FIG. 94 is a table showing the relationship between the film thickness and the medium noise in Example 12 of the present invention. 0115 FIG. 95 is a graph showing the medium noise dependency on the recording density in Example 13 of the present invention. 0116 FIG. 96 is a table showing the relationship between the film thickness and the medium noise in Example 13 of the present invention. 0117 FIG. 97 is a graph showing the medium noise dependency on the recording density in Example 14 of the present invention. 0118 FIG. 98 is a table showing the relationship between the film thickness and the medium noise in Example 14 of the present invention. 0119 FIG. 99 is a graph showing the medium noise dependency on the recording density in Example 15 of the present invention. 0120 FIG. 100 is a table showing the relationship between the film thickness and the medium noise in Example 15 of the present invention. 0121 FIG. 101 is a graph showing the medium noise dependency on the recording density in Example 16 of the present invention. 0122 FIG. 102 is a table showing the relationship between the film thickness and the medium noise in Example 16 of the present invention. 0123 FIG. 103 is a graph showing the medium noise dependency on the recording density in Example 17 of the present invention. 0124 FIG. 104 is a table showing the relationship between the film thickness and the medium noise in Example 17 of the present invention. 0125 FIG. 105 is a graph showing the medium noise dependency on the recording density in Example 18 of the present invention. 0126 FIG. 106 is a table showing the relationship between the film thickness and the medium noise in Example 18 of the present invention. 0127 FIG. 107 is a graph showing the medium noise dependency on the recording density in Example 19 of the present invention. 0128 FIG. 108 is a table showing the relationship between the film thickness and the medium noise in Example 19 of the present invention. 0129 FIG. 109 is a graph showing the medium noise dependency on the recording density in Example 20 of the present invention. 0130 FIG. 110 is a table showing the relationship between the film thickness and the medium noise in Example 20 of the present invention. 0131 FIG. 111 is a table showing values of the perpendicular magnetic anisotropic energy Ku for the respective Examples of the present invention. 0132 FIG. 112 is a graph showing the medium noise dependency on the recording density in Example 21 of the present invention. 0133 FIG. 113 shows the relationship between the film thickness and the medium noise in Example 21 of the present invention. 0134 FIG. 114 is a graph showing the medium noise dependency on the recording density in Example 22 of the present invention. 0135 FIG. 115 shows the relationship between the film thickness and the medium noise in Example 22 of the present invention. 0136 FIG. 116 is a graph showing the medium noise dependency on the recording density in Example 23 of the present invention. 0137 FIG. 117 shows the relationship between the film thickness and the medium noise in Example 23 of the present invention. 0138 FIG. 118 is a graph showing the medium noise dependency on the recording density in Example 24 of the present invention. 0139 FIG. 119 shows the relationship between the film thickness and the medium noise in Example 24 of the present invention. 0140 FIG. 120 is a graph showing the medium noise dependency on the recording density in Example 25 of the present invention. 0141 FIG. 121 shows the relationship between the film thickness and the medium noise in Example 25 of the present invention. 0142 FIG. 122 is a graph showing the medium noise dependency on the recording density in Example 26 of the present invention. 0143 FIG. 123 shows the relationship between the film thickness and the medium noise in Example 26 of the present invention. 0144 FIG. 124 is a graph showing the medium noise dependency on the recording density in Example 27 of the present invention. 0145 FIG. 125 shows the relationship between the film thickness and the medium noise in Example 27 of the present invention. 0146 FIG. 126 is a graph showing the medium noise dependency on the recording density in Example 28 of the present invention. 0147 FIG. 127 shows the relationship between the film thickness and the medium noise in Example 28 of the present invention. 0148 FIG. 128 is a graph showing the medium noise dependency on the recording density in Example 29 of the present invention. 0149 FIG. 129 shows the relationship between the film thickness and the medium noise in Example 29 of the present invention. 0150 FIG. 130 is a graph showing the medium noise dependency on the recording density in Example 30 of the present invention. 0151 FIG. 131 shows the relationship between the film thickness and the medium noise in Example 30 of the present invention. 0152 FIG. 132 is a graph showing the medium noise dependency on the recording density in Example 31 of the present invention. 0153 FIG. 133 shows the relationship between the film thickness and the medium noise in Example 31 of the present invention. 0154 FIG. 134 is a graph showing the medium noise dependency on the recording density in Example 32 of the present invention. 0155 FIG. 135 shows the relationship between the film thickness and the medium noise in Example 32 of the present invention. 0156 FIG. 136 is a graph showing the medium noise dependency on the recording density in Example 33 of the present invention. 0157 FIG. 137 shows the relationship between the film thickness and the medium noise in Example 33 of the present invention. 0158 FIG. 138 is a graph showing the medium noise dependency on the recording density in Example 34 of the present invention. 0159 FIG. 139 shows the relationship between the film thickness and the medium noise in Example 34 of the present invention. 0160 FIG. 140 is a graph showing the medium noise dependency on the recording density in Example 35 of the present invention. 0161 FIG. 141 shows the relationship between the film thickness and the medium noise in Example 35 of the present invention. 0162 FIG. 142 is a graph showing the medium noise dependency on the recording density in Example 36 of the present invention. 0163 FIG. 143 shows the relationship between the film thickness and the medium noise in Example 36 of the present invention. 0164 FIG. 144 is a graph showing the medium noise dependency on the recording density in Example 37 of the present invention. 0165 FIG. 145 shows the relationship between the film thickness and the medium noise in Example 37 of the present invention. 0166 FIG. 146 is a graph showing the medium noise dependency on the recording density in Example 38 of the present invention. 0167 FIG. 147 shows the relationship between the film thickness and the medium noise in Example 38 of the present invention. 0168 FIG. 148 is a graph showing the medium noise dependency on the recording density in Example 39 of the present invention. 0169 FIG. 149 shows the relationship between the film thickness and the medium noise in Example 39 of the present invention. 0170 FIG. 150 is a graph showing the medium noise dependency on the recording density in Example 40 of the present invention. 0171 FIG. 151 shows the relationship between the film thickness and the medium noise in Example 40 of the present invention. 0172 FIG. 152 is a graph showing the medium noise dependency on the recording density in Example 41 of the present invention. 0173 FIG. 153 shows the relationship between the film thickness and the medium noise in Example 41 of the present invention. 0174 FIG. 154 is a graph showing the medium noise dependency on the recording density in Example 42 of the present invention. 0175 FIG. 155 shows the relationship between the film thickness and the medium noise in Example 42 of the present invention. 0176 FIG. 156 is a cross sectional view of a conventional perpendicular magnetic recording medium.
DESCRIPTION OF THE PREFERRED EMBODIMENTS 0177 FIG. 1 to FIG. 6 are cross sectional views of perpendicular magnetic recording media according to the present invention. FIG. 1 shows a perpendicular magnetic recording medium 11 including a perpendicular magnetization film 22 and a high perpendicular orientation film 24 formed in this order on a substrate 20. FIG. 2 shows a perpendicular magnetic recording medium 12 including a high perpendicular orientation film 24 and a perpendicular magnetization film formed in this order on a substrate 20. FIG. 3 shows a perpendicular magnetic recording medium 13 including a high perpendicular orientation film 24, a perpendicular magnetization film 22, and a high perpendicular orientation film 24 formed in this order on a substrate 20. FIG. 4 shows a perpendicular magnetic recording medium 14 including a backing soft magnetic film 26, a perpendicular magnetization film 22, and a high perpendicular orientation film 24 formed in this order on a substrate 20. FIG. 5 shows a perpendicular magnetic recording medium 15 including a backing soft magnetic film 26, a high perpendicular orientation film 24, and a perpendicular magnetization film 22 formed in this order on a substrate 20. FIG. 6 shows a perpendicular magnetic recording medium 15 including a backing soft magnetic film 26, a high perpendicular orientation film 24, a perpendicular magnetization film 22, and a high perpendicular orientation film 24 formed in this order on a substrate 20. 0178 The high perpendicular orientation film 24 has a higher perpendicular orientation characteristic than the perpendicular magnetization film 22. The high perpendicular orientation film 24 may be made from: CoCrM alloys wherein M represents any three elements selected from a group consisting of Pt, Ta, La, Lu, Pr, and Sr; RCo. wherein R represents any one of Y, Ce, Sm, La, and Pr; R2Co17 wherein R represents any one of Y, Ce, Sm, La, and Pr; Ba ferrite, Sr ferrite, PtCo, and the like. 0179 The high perpendicular orientation film 24 made from the aforementioned materials is provided at least over or under the perpendicular magnetization film 22. This reduces effects of the demagnetizing field generated by the magnetic pole on the surface of the perpendicular magnetization film 22. Accordingly, it is possible to obtain a perpendicular magnetic recording medium having a preferable noise characteristic even in the low recording density region.
EXAMPLE 1 0180 Using a 6-inch Co80Cr17Ta3 (%) target for sputtering, a perpendicular magnetization film Co80Cr17Ta3 was formed to have a thickness of 100 nm on a 2.5-inch substrate at 400 degrees centigrade. The film formation conditions were as follows: initial vacuum degree 5107 mTorr; electric power 0.5 kw; argon gas pressure 4 mTorr; film formation speed 3 nm/sec. 0181 After this, the film was covered by the high perpendicular orientation film of 5 to 55 nm thickness formed by using: a Co74Cr22Pt2TaLa target, a Co75Cr21Pt2TaLa target, a Co76Cr20Pt2TaLa target, a Co77Cr19Pt2TaLa target, and a Co78Cr18Pt2TaLa target. 0182 After this, a C (carbon) protection film 10 nm was formed to cover the high perpendicular orientation film. 0183 The medium having the high perpendicular orientation film of Co76Cr20Pt2TaLa of 50 nm thickness will be referred to as medium AAA2 of the present invention. On the other hand, the medium having only the perpendicular magnetization film Co80Cr17Ta3without forming the high perpendicular orientation film of Co76Cr20Pt2TaLa will be referred to as a conventional medium (comparative example) D1. 0184 It should be noted we also prepared a medium having the Co76Cr20Pt2TaLa film and the Co80Cr17Ta3 film in the reversed order. That is, firstly, Co75Cr20Pt2TaLa film was formed on the substrate, and then the Co80Cr17Ta3 film was formed on the Co76Cr20Pt2TaLa film. 0185 The perpendicular magnetic anisotropic energy Ku of the following seven films were measured using a torque magnetometer; and saturation magnetization Ms of the seven films were measured using a sample vibration type magnetometer (VSM): a Co74Cr22Pt2TaLa film, a Co75Cr21Pt2TaLa film, a Co76Cr20Pt2TaLa film, a Co77Cr19Pt2TaLa film, a Co78Cr18Pt2TaLa film, a Co78Cr19Ta3 film, and a Co80Cr17Ta3 film. The measurement results are shown in FIG. 7. 0186 In general, a magnetic film can be a perpendicular magnetization film if the perpendicular anisotropy magnetic field Hk is greater than the maximum perpendicular magnetic field 4 pMs (p represents the number ) so as to satisfy the relationship of Hk4 pMs. Moreover, the perpendicular anisotropy magnetic field Hk can be expressed by using the perpendicular magnetic anisotropic energy Ku, i.e., Hk2Ku/Ms. That is, the quality of the perpendicular orientation of the perpendicular magnetization film can be determined by finding which is greater Hk or 4 pMs. Here, R is assumed to be Hk/4 pMs, and the R values are shown in the table of FIG. 7. 0187 The Co80Cr17Ta3 film-has R1.1 whereas the Co76Cr20Pt2TaLa film has R1.4. That is the Co76Cr20Pt2TaLa film has by far better perpendicular magnetic anisotropy than the Co80Cr17Ta3 film. However, if the percentage content of the Co is 73% or below, the Co alloy does not show the ferromagnetic characteristic. Accordingly, it is impossible to lower the Co content without limit. 0188 On the other hand, by using the ID (inductive)/MR(magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium AAA2 of the present invention and the conventional medium D1. The check conditions were set as follows: ID/MR composite head recording track width 4 micrometers, the reproduction track width 3 micrometers, recording gap length 0.4 micrometers, and reproduction gap length 0.32 micrometers. Evaluation of the check was performed under the conditions of: recording current 19 mAop, sense current 12 mA, peripheral velocity 12.7 m/s, floating amount 45 nm, and noise bandwidth 50 MHz. 0189 FIG. 8 shows the medium noise dependency on the recording density for the AAA2 of the present invention and the conventional D1. As is clear from FIG. 8, the conventional medium D1 shows a very high medium noise in the lower recording density, whereas in the medium AAA2 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium D1. This is because the medium AAA2 of the present invention includes a film having a preferable perpendicular magnetic anisotropy on the perpendicular magnetization film of Co80Cr17Ta3. Accordingly, in contrast to the conventional D1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0190 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 9 to FIG. 13. As is clear from FIG. 9 to FIG. 13, when the value R (Hk/4 pMs) is smaller than 1.4, medium noise cannot be improved even if the film thickness is reduced. This is because if R is below 1.4, the perpendicular orientation characteristic is insufficient and it is impossible to sufficiently suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. On the other hand, if the film satisfies the relationship that R is equal to or greater than 1.4, the medium noise is reduced up to the film thickness 50 nm for all the film types. As has been described above, if a film satisfies the relationship that R is equal to or greater than 1.4, it is possible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. However, even if the film satisfies the aforementioned relationship, the medium noise reduction cannot be seen when the film thickness exceeds 50 nm. This is because of the fact that if the film thickness is too great, the orientation perpendicular to the film surface is deteriorated and it is impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0191 As has been described above, the recording medium AAA2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the AAA2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. Moreover, when the Co76Cr20Pt2TaLa film is provided under or both under and over the perpendicular magnetization film, similar results can be obtained because of the aforementioned reasons. Furthermore, film types other than the Co76Cr20Pt2TaLa film can also have similar results if the relationship that R is equal to or more than 1.4 is satisfied.
EXAMPLE 2 0192 Media of Example 2 were prepared in the same way as Example 1 except for that the CoxCr96.xPt2TaLa (7478) target was replaced by CoxCr96.xPt2TaLu (7478) target. The medium examples made from Co76Cr20Pt2TaLu film having a film thickness of 50 nm will be referred to as medium BBB2 of the present invention. Note that we also prepared media having the Co80Cr17Ta3 film and the Co76Cr20Pt2TaLu film in the reversed order, i.e., firstly Co76Cr20Pt2TaLu film was formed on the substrate, and then the Co80Cr17Ta3 film was formed thereon. 0193 The perpendicular magnetic anisotropic energy Ku of the following six films were measured using a torque magnetometer; and saturation magnetization Ms of these six films were measured using a sample vibration type magnetometer (VSM): a Co74Cr22Pt2TaLu film, a Co75Cr21Pt2TaLu film, a Co76Cr20Pt2TaLu film, a Co77Cr19Pt2TaLu film, a Co78Cr18Pt2TaLu film, and a Co80Cr17Ta3 film. The check results are shown in FIG. 14 and FIG. 7. 0194 Here, R is defined as Hk/4 pMs in the same way as in Example 1. FIG. 14 shows the R values for each of the films. The Co20Cr17Ta3 film has R1.1 whereas the Co76Cr20Pt2TaLu film has R1.4. That is, the Co76Cr20Pt2TaLu film shows by far more preferable perpendicular magnetic anisotropy than the Co80Cr17Ta3 film. However, the Co alloy film having Co content 73 or below does not show the ferromagnetic characteristic. Accordingly, it is impossible to reduce the Co content without limit. 0195 The ID/MR composite head was used to check the recording/reproduction characteristic of the medium BBB2 of the present invention and the conventional medium (comparative example) D1. The head and the recording/reproduction conditions were set in the same way as in Example 1. 0196 FIG. 15 shows the medium noise dependency on the recording density for the BBB2 of the present invention and the conventional medium D1. As is clear from FIG. 15, the conventional medium D1 has a very high noise in the low recording medium region, whereas the medium BBB2 of the present invention shows noise by far lower than the conventional medium D1 in the low recording density region. This is because the BBB2 has a preferable film of perpendicular magnetic anisotropy on the perpendicular magnetization film of Co80Cr17Ta3 and it is possible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film much more than the conventional medium D1. 0197 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 16 to FIG. 20. As is clear from FIG. 16 to FIG. 20, when the value R (Hk/4 pMs) is smaller than 1.4, medium noise cannot be improved even if the film thickness is reduced. This is because if R is below 1.4, the perpendicular orientation characteristic is insufficient and it is difficult to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. On the other hand, if the film satisfies the relationship that R is equal to or greater than 1.4, the medium noise is reduced up to the film thickness 50 nm for all the film types. As has been described above, in the film which satisfies the relationship that R is equal to or greater than 1.4, it is possible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. However, even if the film satisfies the aforementioned relationship, the medium noise reduction cannot be seen when the film thickness exceeds 50 nm. This is because of the fact that if the film thickness is too great, the orientation perpendicular to the film surface is deteriorated and it is impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0198 As has been described above, the recording medium BBB2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the BBB2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. Moreover, when the Co76Cr20Pt2TaLu film is provided under or both under and over the perpendicular magnetization film, similar results can be obtained because of the aforementioned reasons. Furthermore, film types other than the Co76Cr20Pt2TaLu film can also have similar results if the relationship that R is equal to or more than 1.4 is satisfied.
EXAMPLE 3 0199 Media of Example 3 were prepared in the same way as Example 1 except for that the CoxCr96.xPt2TaLa (7478) target was replaced by CoxCr96.xPt2LaLu (7478) target. The medium examples made from Co76Cr20Pt2LaLu film having a film thickness of 50 nm will be referred to as medium CCC2 of the present invention. Note that we also prepared media having the Co80Cr17Ta3 film and Co76Cr20Pt2LaLu film in the reversed order, i.e., firstly Co76Cr20Pt2LaLu film was formed on the substrate, and then the Co80Cr17Ta3 film was formed thereon. 0200 The perpendicular magnetic anisotropic energy Ku of the following six films were measured using a torque magnetometer; and saturation magnetization Ms of these six films were measured using a sample vibration type magnetometer (VSM): a Co74Cr22Pt2LaLu film, a Co75Cr21Pt2LaLu film, a Co76Cr20Pt2LaLu film, a Co77Cr19Pt2LaLu film, a Co78Cr18Pt2LaLu film, and a Co80Cr17Ta3 film. The check results are shown in FIG. 21 and FIG. 7. 0201 Here, R is defined as Hk/4 pMs in the same way as in Example 1. FIG. 21 shows the R values for each of the films. The Co80Cr17Ta3 film has R1.1 whereas the Co76Cr20Pt2LaLu film has R1.4. That is, the Co76Cr20Pt2LaLu film shows by far more preferable perpendicular magnetic anisotropy than the Co80Cr17Ta3 film. However, the Co alloy film having Co content 73 or below does not show the ferromagnetic characteristic. Accordingly, it is impossible to reduce the Co content without limit. 0202 The ID/MR composite head was used to check the recording/reproduction characteristic of the medium CCC2 of the present invention and the conventional medium (comparative example) D1. The head and the recording/reproduction conditions were set in the same way as in Example 1. 0203 FIG. 22 shows the medium noise dependency on the recording density for the CCC2 of the present invention and the conventional medium D1. As is clear from FIG. 22, the conventional medium D1 has a very high noise in the low recording medium region, whereas the medium CCC2 of the present invention shows noise by far lower than the conventional medium D1 in the low recording density region. This is because the CCC2 has a preferable film of perpendicular magnetic anisotropy on the perpendicular magnetization film of Co80Cr17Ta3 and it is possible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film much more than the conventional medium D1. 0204 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 23 to FIG. 27. As is clear from FIG. 23 to FIG. 27, when the value R (Hk/4 pMs) is smaller than 1.4, medium noise cannot be improved even if the film thickness is reduced. This is because if R is below 1.4, the perpendicular orientation characteristic is insufficient and it is difficult to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. On the other hand, if the film satisfies the relationship that R is equal to or greater than 1.4, i.e., R1.4, the medium noise is reduced up to the film thickness 50 nm for all the film types. As has been described above, in the film which satisfies the relationship that R is equal to or greater than 1.4, it is possible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. However, even if the film satisfies the aforementioned relationship, the medium noise reduction cannot be seen when the film thickness exceeds 50 nm. This is because of the fact that if the film thickness is too great, the orientation perpendicular to the film surface is deteriorated and it is impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0205 As has been described above, the recording medium CCC2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the CCC2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. Moreover, when the Co76Cr20Pt2LaLu film is provided under or both under and over the perpendicular magnetization film, similar results can be obtained because of the aforementioned reasons. Furthermore, film types other than the Co76Cr20Pt2LaLu film can also have similar results if the relationship that R is equal to or more than 1.4 is satisfied.
EXAMPLE 4-1 0206 Media of Example 4-1 were prepared in the same way as Example 1 except for that the CoxCr96.xPt2TaLa (7478) target was replaced by CoxCr96.xTa2LaLu (7478) target. The medium examples made from Co76Cr20Ta2LaLu film having a film thickness of 50 nm will be referred to as medium DDD2 of the present invention. Note that we also prepared media having the Co80Cr17Ta3 film and Co76Cr20Ta2LaLu film in the reversed order, i.e., firstly Co76Cr20Ta2LaLu film was formed on the substrate, and then the Co80Cr17Ta3 film was formed thereon. 0207 FIG. 28 and FIG. 7 show the perpendicular magnetic anisotropic energy Ku and saturation magnetization Ms of the six films: a Co74Cr22Ta2LaLu film, a Co75Cr21Ta2LaLu film, a Co76Cr20Ta2LaLu film, a Co77Cr19Ta2LaLu film, a Co78Cr18Ta2LaLu film, and a Co80Cr17Ta3 film. 0208 Here, the R is defined in the same way as in Example 1. FIG. 28 shows the respective R values. The Co80Cr17Ta3 film has R1.1, whereas the Co76Cr20Ta2LaLu film, for example, has R1.4. That is, the Co76Cr20Ta2LaLu film has by far preferable perpendicular magnetic compared to the Co80Cr17Ta3 film. However, if Co content is equal to or below 73, the Co alloy does not exhibit the ferromagnetic characteristic. Accordingly, it is impossible to reduce the Co content without limit. 0209 The ID/MR composite head was used to check the reproduction characteristic of the DDD2 of the present invention and the conventional medium D1. The head and the recording/reproduction conditions were set the same as in Example 1. 0210 FIG. 29 shows the medium noise dependency on the recording density for the DDD2 of the present invention and the conventional medium D1. As is clear from FIG. 29, the conventional medium D1 has a very high noise in the low recording medium region, whereas the medium DDD2 of the present invention shows noise by far lower than the conventional medium D1 in the low recording density region. This is because the DDD2 has a preferable film of perpendicular magnetic anisotropy on the perpendicular magnetization film of Co80Cr17Ta3 and it is possible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film much more than the conventional medium D1. 0211 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at 4, recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 30 to FIG. 34. As is clear from FIG. 30 to FIG. 34, when the value R (Hk/4 pMs) is smaller than 1.4, medium noise cannot be improved (reduced) even if the film thickness is reduced. This is because if R is below 1.4, the perpendicular orientation characteristic is insufficient and it is difficult to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. On the other hand, if the film satisfies the relationship that R is equal to or greater than 1.4, i.e., R1.4, the medium noise is reduced up to the film thickness 50 nm for all the film types. As has been described above, in the film which satisfies the relationship that R is equal to or greater than 1.4, it is possible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. However, even if the film satisfies the aforementioned relationship, the medium noise reduction cannot be seen when the film thickness exceeds 50 nm. This is because of the fact that if the film thickness is too great, the orientation perpendicular to the film surface is deteriorated and it is impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0212 As has been described above, the recording medium DDD2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the DDD2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. Moreover, when the Co76Cr20Ta2LaLu film is provided under or both under and over the perpendicular magnetization film, similar results can be obtained because of the aforementioned reasons. Furthermore, film types other than the Co76Cr20Ta2LaLu film can also have similar results if the relationship that R is equal to or more than 1.4 is satisfied.
EXAMPLE 4-2 0213 Media of Example 4-1 were prepared in the same way as Example 1 except for that the CoxCr96.xPt2TaLa (74 78) target was replaced by CoxCr96-xTa2PrSr (7478) target. The medium examples made from Co76Cr20Ta2PrSr film having a film thickness of 50 nm will be referred to as medium DDD3 of the present invention. Note that we also prepared media having the Co80Cr17Ta3 film and Co76Cr20Ta2PrSr film in the reversed order, i.e., firstly Co76Cr20Ta2PrSr film was formed on the substrate, and then the Co80Cr17Ta3 film was formed thereon. 0214 The perpendicular magnetic anisotropic energy Ku of the following six films were measured using a torque magnetometer; and saturation magnetization Ms of these six films were measured using a sample vibration type magnetometer (VSM): i.e., a Co74Cr22Ta2PrSr film, a Co76Cr21Ta2PrSr film, a Co76Cr20Ta2PrSr film, a Co77Cr19Ta2PrSr film, a Co78Cr18Ta2PrSr film, and a Co80Cr17Ta3 film. The check results are shown in FIG. 35 and FIG. 7. 0215 Here, R is defined as Hk/4 pMs in the same way as in Example 1. FIG. 35 shows the R values for each of the films. The Co80Cr17Ta3 film has R1.1 whereas the Co76Cr20Ta2PrSr film has R1.4. That is, the Co76Cr20Ta2PrSr film shows by far more preferable perpendicular magnetic anisotropy than the Co80Cr17Ta3 film. However, the Co alloy film having Co content 73 or below does not show the ferromagnetic characteristic. Accordingly, it is impossible to reduce the Co content without limit. 0216 The ID/MR composite head was used to check the recording/reproduction characteristic of the medium DDD3 of the present invention and the conventional medium (comparative example) D1. The head and the recording/reproduction conditions were set in the same way as in Example 1. 0217 FIG. 36 shows the medium noise dependency on the recording density for the DDD3 of the present invention and the conventional medium D1. As is clear from FIG. 36, the conventional medium D1 has a very high noise in the low recording medium region, whereas the medium DDD3 of the present invention shows noise by far lower than the conventional medium D1 in the low recording density region. This is because the DDD3 has a preferable film of perpendicular magnetic anisotropy on the perpendicular magnetization film of Co80Cr17Ta3 and it is possible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film much more than the conventional medium D1. 0218 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 37 to FIG. 41. As is clear from FIG. 37 to FIG. 41, when the value R (Hk/4 pMs) is smaller than 1.4, medium noise cannot be improved (reduced) even if the film thickness is reduced. This is because if R is below 1.4, the perpendicular orientation characteristic is insufficient and it is difficult to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. On the other hand, if the film satisfies the relationship that R is equal to or greater than 1.4, i.e., R1.4, the medium noise is reduced up to the film thickness 50 nm for all the film types. As has been described above, in the film which satisfies the relationship that R is equal to or greater than 1.4, it is possible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. However, even if the film satisfies the aforementioned relationship, the medium noise reduction cannot be seen when the film thickness exceeds 50 nm. This is because of the fact that if the film thickness is too great, the orientation perpendicular to the film surface is deteriorated and it is impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0219 As has been described above, the recording medium DDD3 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the DDD3 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. Moreover, when the Co76Cr20Ta2PrSr film is provided under or both under and over the perpendicular magnetization film, similar results can be obtained because of the aforementioned reasons. Furthermore, film types other than the Co80Cr20Ta2PrSr film can also have similar results if the relationship that R is equal to or more than 1.4 is satisfied.
EXAMPLE 5 0220 Using a 6-inch FeSiAl target for sputtering, a FeSiAl film was formed with a thickness of 500 nm on 2.5-inch substrates. The film formation conditions were as follows: initial vacuum degree 5107 mTorr; electric power 0.5 kw; argon gas pressure 4 mTorr; film formation speed 3 nm/sec. 0221 Then, each of the FeSiAl films on the substrates at temperature of 400 degrees centigrade was covered by 100 nm of Co80Cr17Ta3 film formed by using a Co80Cr17Ta3 target under the same film formation conditions as FeSiAl. 0222 Next, the Co80Cr17Ta3 films were respectively covered by 5 to 55 nm thickness of a Co74Cr22Pt2TaLa film, a Co75Cr21Pt2TaLa film, a Co76Cr20Pt2TaLa film, a Co77Cr19Pt2TaLa film, and a Co77Cr19Pt2TaLa film by using the corresponding targets. Furthermore, a C (carbon) protection film of 10 nm was formed to cover the aforementioned films. 0223 The medium having the Co76Cr20Pt2TaLa film of 50 nm will be referred to as AAAA2 of the present invention. On the other hand, the medium having only the Co80Cr17Ta3 film on the FeSiAl film without forming the Co76Cr20Pt2TaLa film will be referred to as a conventional medium (comparative example) E1. 0224 It should be noted we also prepared a medium having the Co76Cr20Pt2TaLa film and the Co80Cr17Ta3 film in the reversed order. That is, firstly, Co76Cr20Pt2TaLa film was formed on the substrate, and then the Co80Cr17Ta3 film was formed on the Co76Cr20Pt2TaLa film. 0225 FIG. 7 shows the perpendicular magnetic anisotropic energy Ku and saturation magnetization Ms of the Co74Cr22Pt2TaLa film, the Co75Cr21Pt2TaLa film, the Co76Cr20Pt2TaLa film, the Co77Cr19Pt2TaLa film, the Co78Cr18Pt2TaLa film, and the Co80Cr17Ta3 film. 0226 By using a mono-pole/MR (magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium AAAA2 of the present invention and the conventional medium E1. The check conditions were set as follows: mono-pole head recording track width 4 micrometers, the main magnetic pole film thickness 0.4 micrometers, reproduction track width 3 micrometers, and reproduction gap length 0.32 micrometers. Note that the check was performed under the condition of: recording current 10 mAop, sense current 12 mA, peripheral velocity 12.7 m/s, and floating amount 45 nm. 0227 FIG. 42 shows the medium noise dependency on the recording density for the AAAA2 of the present invention and the conventional medium E1. As is clear from FIG. 42, the conventional medium E1 shows a very high medium noise in the lower recording density, whereas in the medium AAAA2 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium E1. This is because the medium AAAA2 of the present invention includes a film having a preferable perpendicular magnetic anisotropy on the perpendicular magnetization film of Co80Cr17Ta3. Accordingly, in contrast to the conventional E1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. Note that the FeSiAl film has no magnetic domain wall structure and the spike-shaped noise is not generated easily due to the magnetic domain wall movement. 0228 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 43 to FIG. 47. As is clear from FIG. 43 to FIG. 47, when the value R (Hk/4 pMs) is smaller than 1.4, medium noise cannot be improved (reduced) even if the film thickness is reduced. This is because if R is below 1.4, the perpendicular orientation characteristic is insufficient and it is impossible to sufficiently suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0229 On the other hand, if the film satisfies the relationship that R is equal to or greater than 1.4, the medium noise is reduced up to the film thickness 50 nm for all the film types. As has been described above, if a film satisfies the relationship that R is equal to or greater than 1.4, it is possible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. However, even if the film satisfies the aforementioned relationship, the medium noise reduction cannot be seen when the film thickness exceeds 50 nm. This is because of the fact that if the film thickness is too great, the orientation perpendicular to the film surface is deteriorated and it is impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0230 As has been described above, the recording medium AAAA2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the AAAA2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. Moreover, when the Co76Cr20Pt2TaLa film is provided under or both under and over the perpendicular magnetization film, similar results can be obtained because of the aforementioned reasons. Furthermore, film types other than the Co76Cr20Pt2TaLa film can also have similar results if the relationship that R is equal to or more than 1.4 is satisfied. 0231 Moreover, in the experiment using the ID/MR composite head used in Example 1 instead of the mono-pole composite head, similar results were obtained because of the aforementioned reasons.
EXAMPLE 6 0232 Media of Example 6 were prepared in the same way as Example 5 except for that the CoxCr96.xPt2TaLa (7478) target was replaced by CoxCr96.xTa2TaLu (7478) target. The medium examples made from Co76Cr20Pt2TaLu film having a film thickness of 50 nm will be referred to medium BBBB2 of the present invention. Note that we also prepared media having the Co80Cr17Ta3 film and Co76Cr20Ta2LaLu film in the reversed order, i.e., firstly Co76Cr20Ta2LaLu film was formed on the substrate, and then the Co80Cr17Ta3 film was formed thereon. 0233 FIG. 7 shows the perpendicular magnetic anisotropic energy Ku and saturation magnetization Ms of the Co74Cr22Pt2TaLu film, the Co75Cr21Pt2TaLu film, the Co76Cr20Pt2TaLu film, the Co76Cr19Pt2TaLu film, the CO78Cr18Pt2TaLu film, and the Co80Cr17Ta3 film. 0234 By using a mono-pole/MR (magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium BBBB2 of the present invention and the conventional medium E1. The check conditions and head characteristics were the same as in Example 5. 0235 FIG. 48 shows the medium noise dependency on the recording density for the BBBB2 of the present invention and the conventional medium E1. As is clear from FIG. 48, the conventional medium E1 shows a very high medium noise in the lower recording density, whereas in the medium BBBB2 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium E1. This is because the medium BBBB2 of the present invention includes a film having a preferable perpendicular magnetic anisotropy on the perpendicular magnetization film of Co80Cr17Ta3. Accordingly, in contrast to the conventional E1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. Note that the FeSiAl film has no magnetic domain wall structure and the spike-shaped noise is not easily caused by the magnetic domain wall movement. 0236 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 49 to FIG. 53. As is clear from FIG. 49 to FIG. 53, when the value R (Hk/4 pMs) is smaller than 1.4, medium noise cannot be improved (reduce) even if the film thickness is reduced. This is because if R is below 1.4, the perpendicular orientation characteristic is insufficient and it is impossible to sufficiently suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0237 On the other hand, if the film satisfies the relationship that R is equal to or greater than 1.4, the medium noise is reduced up to the film thickness 50 nm for all the film types. As has been described above, if a film satisfies the relationship that R is equal to or greater than 1.4, it is possible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. However, even if the film satisfies the aforementioned relationship, the medium, noise reduction cannot be seen when the film thickness exceeds 50 nm. This is because of the fact that if the film thickness is too great, the orientation perpendicular to the film surface is deteriorated and it is impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0238 As has been described above, the recording medium BBBB2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the BBBB2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. 0239 Moreover, when the Co76Cr20Pt2TaLu film is provided under or both under and over the perpendicular magnetization film, similar results can be obtained because of the aforementioned reasons. Furthermore, film types other than the Co76Cr20Pt2TaLu film can also have similar results if the relationship that R is equal to or more than 1.4 is satisfied.
EXAMPLE 7 0240 Media of Example 7 were prepared in the same way as Example 5 except for that the CoxCr96.xPt2TaLa (7478) target was replaced by CoxCr96.xPt2LaLu (7478) target. The medium examples made from Co76Cr20Pt2LaLu film having a film thickness of 50 nm will be referred to medium CCCC2 of the present invention. Note that we also prepared media having the Co80Cr17Ta3 film and Co76Cr20Pt2LaLu film in the reversed order, i.e., firstly Co76Cr20Pt2LaLu film was formed on the substrate, and then the Co80Cr17Ta3 film was formed thereon. 0241 FIG. 21 and FIG. 7 shows the perpendicular magnetic anisotropic energy Ku and saturation magnetization Ms of the Co74Cr22Pt2LaLu film, the Co75Cr21Pt2zLaLu film, the Co76Cr20Pt2LaLu film, the Co77Cr19Pt2LaLu film, the Co78Cr18Pt2LaLu film, and the Co80Cr17Ta3 film. 0242 By using a mono-pole/MR (magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium CCCC2 of the present invention and the conventional medium E1. The check conditions and head characteristics were the same as in Example 5. 0243 FIG. 54 shows the medium noise dependency on the recording density for the CCCC2 of the present invention and the conventional medium E1. As is clear from FIG. 54, the conventional medium E1 shows a very high medium noise in the lower recording density, whereas in the medium CCCC2 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium E1. This is because the medium CCCC2 of the present invention includes a film having a preferable perpendicular magnetic anisotropy on the perpendicular magnetization film of Co80Cr17Ta3. Accordingly, in contrast to the conventional E1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. Note that the FeSiAl film has no magnetic domain wall structure and the spike-shaped noise is not easily caused by the magnetic domain wall movement. 0244 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 55 to FIG. 59. As is clear from FIG. 55 to FIG. 59, when the value R (Hk/4 pMs) is smaller than 1.4, medium noise cannot be improved even if the film thickness is reduced. This is because if R is below 1.4, the perpendicular orientation characteristic is insufficient and it is impossible to sufficiently suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0245 On the other hand, if the film satisfies the relationship that R is equal to or greater than 1.4, the medium noise is reduced up to the film thickness 50 nm for all the film types. As has been described above, if a film satisfies the relationship that R is equal to or greater than 1.4, it is possible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. However, even if the film satisfies the aforementioned relationship, the medium noise reduction cannot be seen when the film thickness exceeds 50 nm. This is because of the fact that if the film thickness is too great, the orientation perpendicular to the film surface is deteriorated and it is impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0246 As has been described above, the recording medium CCCC2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the CCCC2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. Moreover, when the Co76Cr20Pt2LaLu film is provided under or both under and over the perpendicular magnetization film, similar results can be obtained because of the aforementioned reasons. Furthermore, film types other than the Co76Cr20Pt2LaLu film can also have similar results if the relationship that R is equal to or more than 1.4 is satisfied. 0247 Moreover, experiments were performed using the ID/MR composite head used in Example 1, instead of the mono-pole/MR composite head. The experiments showed results similar to the aforementioned results.
EXAMPLE 8-1 0248 Media of Example 8-1 were prepared in the same way as Example 5 except for that the CoxCr96.xPt2TaLa (7478) target was replaced by CoxCr96.xTa2LaLu (7478) target. The medium examples made from Co76Cr20Ta2LaLu film having a film thickness of 50 nm will be referred to as medium DDDD2 of the present invention. Note that we also prepared media having the Co80Cr17Ta3 film and Co76Cr20Ta2LaLu film in the reversed order, i.e., firstly Co76Cr20Ta2LaLu film was formed on the substrate, and then the Co80Cr17Ta3 film was formed thereon. 0249 FIG. 28 and FIG. 7 show the perpendicular magnetic anisotropic energy Ku and saturation magnetization Ms of the Co74Cr22Ta2LaLu film, the Co75Cr21Ta2LaLu film, the Co76Cr20Ta2LaLu film, the Co77Cr19Ta2LaLu film, the Co78Cr18Ta2LaLu film, and the Co80Cr17Ta3 film. 0250 By using a mono-pole/MR (magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium DDDD2 of the present invention and the conventional medium E1. The check conditions and head characteristics were the same as in Example 5. 0251 FIG. 60 shows the medium noise dependency on the recording density for the DDDD2 of the present invention and the conventional medium E1. As is clear from FIG. 60, the conventional medium E1 shows a very high medium noise in the lower recording density, whereas in the medium DDDD2 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium E1. This is because the medium DDDD2 of the present invention includes a film having a preferable perpendicular magnetic anisotropy on the perpendicular magnetization film of Co80Cr17Ta3. Accordingly, in contrast to the conventional E1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. Note that the FeSiAl film has no magnetic domain wall structure and the spike-shaped noise is not easily caused by the magnetic domain wall movement. 0252 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 61 to FIG. 65. As is clear from FIG. 61 to FIG. 65, when the value R (Hk/4 pMs) is smaller than 1.4, medium noise cannot be improved (reduced) even if the film thickness is reduced. This is because if R is below 1.4, the perpendicular orientation characteristic is insufficient and it is impossible to sufficiently suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. On the other hand, if the film satisfies the relationship that R is equal to or greater than 1.4, the medium noise is reduced up to the film thickness 50 nm for all the film types. As has been described above, if a film satisfies the relationship that R is equal to or greater than 1.4, it is possible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. However, even if the film satisfies the aforementioned relationship, the medium noise reduction cannot be seen when the film thickness exceeds 50 nm. This is because of the fact that if the film thickness is too great, the orientation perpendicular to the film surface is deteriorated and it is impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0253 As has been described above, the recording medium DDDD2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the DDDD2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. Moreover, when the Co76Cr20Ta2LaLu film is provided under or both under and over the perpendicular magnetization film, similar results can be obtained because of the aforementioned reasons. Furthermore, film types other than the Co76Cr20Ta2LaLu film can also have similar results if the relationship that R is equal to or more than 1.4 is satisfied. 0254 Moreover, experiment was performed using the ID/MR composite head used in Example 1, instead of the mono-pole/MR composite head. The experiment showed results similar to the aforementioned results.
EXAMPLE 8-2 0255 Media of Example 8-2 were prepared in the same way as Example 5 except for that the CoxCr96.xPt2TaLa (7478) target was replaced by CoxCr96.xTa2PrSr (7478) target. The medium examples made from Co76Cr20Ta2PrSr film having a film thickness of 50 nm will be referred to as medium DDDD3 of the present invention. Note that we also prepared media having the Co80Cr17Ta3 film and Co76Cr2Ta2PrSr film in the reversed order, i.e., firstly Co76Cr20Ta2PrSr film was formed on the substrate, and then the Co80Cr17Ta3 film was formed thereon. 0256 FIG. 35 and FIG. 7 shows the perpendicular magnetic anisotropic energy Ku and saturation magnetization Ms of the Co74Cr22Ta2PrSr film, the Co75Cr21Ta2PrSr film, the Co76Cr20Ta2PrSr film, the Co77Cr19Ta2PrSr film, the Co78Cr18 Ta2LaLu film, and the Co80Cr17Ta3 film. 0257 By using a mono-pole/MR (magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium DDDD3 of the present invention and the conventional medium E1. The check conditions and head characteristics were the same as in Example 5. 0258 FIG. 66 shows the medium noise dependency on the recording density for the DDDD3 of the present invention and the conventional medium E1. As is clear from FIG. 66, the conventional medium E1 shows a very high medium noise in the lower recording density, whereas in the medium DDDD3 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium E1. This is because the medium DDDD3 of the present invention includes a film having a preferable perpendicular magnetic anisotropy on the perpendicular magnetization film of Co80Cr17Ta3. Accordingly, in contrast to the conventional E1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. Note that the FeSiAl film has no magnetic domain wall structure and the spike-shaped noise is not easily caused by the magnetic domain wall movement. 0259 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 67 to FIG. 71. As is clear from FIG. 67 to FIG. 71, when the value R (Hk/4 pMs) is smaller than 1.4, medium noise cannot be improved (reduced) even if the film thickness is reduced. This is because if R is below 1.4, the perpendicular orientation characteristic is insufficient and it is impossible to sufficiently suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0260 On the other hand, if the film satisfies the relationship that R is equal to or greater than 1.4, the medium noise is reduced up to the film thickness 50 nm for all the film types. As has been described above, if a film satisfies the relationship that R is equal to or greater than 1.4, it is possible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. However, even if the film satisfies the aforementioned relationship, the medium noise reduction cannot be seen when the film thickness exceeds 50 nm. This is because of the fact that if the film thickness is too great, the orientation perpendicular to the film surface is deteriorated and it is impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0261 As has been described above, the recording medium DDDD3 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the DDDD3 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. Moreover, when the Co76Cr20Ta2PrSr film is provided under or both under and over the perpendicular magnetization film, similar results can be obtained because of the aforementioned reasons. Furthermore, film types other than the Co76Cr20Ta2PrSr film can also have similar results if the relationship that R is equal to or more than 1.4 is satisfied. 0262 Moreover, experiment was performed using the ID/MR composite head used in Example 1, instead of the mono-pole/MR composite head. The experiment showed results similar to the aforementioned results.
EXAMPLE 9 0263 Media of Example 9 were prepared in the same way as in Example 5 except for that the FeSiAl target for sputtering was replaced by FeTaN target. 0264 The medium having the Co76Cr20Pt2TaLa film of 50 nm will be referred to as EEEE2 of the present invention. On the other hand, the medium having only the Co80Cr17Ta3 film on the FeTaN film without forming the Co76Cr20Pt2TaLa film will be referred to as a conventional medium (comparative example) F1. 0265 It should be noted we also prepared a medium having the Co76Cr20Pt2TaLa film and the Co80Cr17Ta3 film in the reversed order. That is, firstly, Co76Cr20Pt2TaLa film was formed on the substrate, and then the Co80Cr17Ta3 film was formed on the Co76Cr20Pt2TaLa film. 0266 FIG. 7 shows the perpendicular magnetic anisotropic energy Ku and saturation magnetization Ms of the Co74Cr22Pt2TaLa film, the Co75Cr21Pt2TaLa film, the Co76Cr20Pt2TaLa film, the Co77Cr19Pt2TaLa film, the Co78Cr18Pt2TaLa film, and the Co80Cr17Ta3 film. 0267 By using a mono-pole/MR (magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium EEEE2 of the present invention and the conventional medium F1. The check conditions and the head characteristics were set in the same way as Example 5. 0268 FIG. 72 shows the medium noise dependency on the recording density for the EEEE2 of the present invention and the conventional medium F1. As is clear from FIG. 72, the conventional medium F1 shows a very high medium noise in the lower recording density, whereas in the medium EEEE2 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium F1. This is because the medium EEEE2 of the present invention includes a film having a preferable perpendicular magnetic anisotropy on the perpendicular magnetization film of Co80Cr17Ta3. Accordingly, in contrast to the conventional F1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0269 Note that the FeTaN film has no magnetic domain wall structure and the spike-shaped noise is not generated easily due to the magnetic domain wall movement. 0270 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 73 to FIG. 77. As is clear from FIG. 73 to FIG. 77, when the value R (Hk/4 pMs) is smaller than 1.4, medium noise cannot be improved (reduced) even if the film thickness is reduced. This is because if R is below 1.4, the perpendicular orientation characteristic is insufficient and it is impossible to sufficiently suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0271 On the other hand, if the film satisfies the relationship that R is equal to or greater than 1.4, the medium noise is reduced up to the film thickness 50 nm for all the film types. As has been described above, if a film satisfies the relationship that R is equal to or greater than 1.4, it is possible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. However, even if the film satisfies the aforementioned relationship, the medium noise reduction cannot be seen when the film thickness exceeds 50 nm. This is because of the fact that if the film thickness is too great, the orientation perpendicular to the film surface is deteriorated and it is impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0272 As has been described above, the recording medium EEEE2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the EEEE2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. Moreover, when the Co76Cr20Pt2TaLa film is provided under or both under and over the perpendicular magnetization film, similar results can be obtained because of the aforementioned reasons. Furthermore, film types other than the Co76Cr20Pt2TaLa film can also have similar results if the relationship that R is equal to or more than 1.4 is satisfied. 0273 Moreover, in the experiment using the ID/MR composite head used in Example 1 instead of the mono-pole composite head, similar results were obtained because of the aforementioned reasons.
EXAMPLE 10-1 0274 Media of Example 10-1 were prepared in the same way as in Example 9 except for that the CoxCr96.xPt2TaLa (7478) target was replaced by CoxCr96.xPt2TaLu (7478) target. The medium having the Co76Cr20Pt2TaLu film of 50 nm will be referred to as FFFF2 of the present invention. 0275 It should be noted we also prepared a medium having the Co76Cr20Pt2TaLu film and the Co80Cr17Ta3 film in the reversed order. That is, firstly, Co76Cr20Pt2TaLu film was formed on the substrate, and then the Co80Cr17Ta3 film was formed on the Co76Cr20Pt2TaLu film. 0276 FIG. 7 shows the perpendicular magnetic anisotropic energy Ku and saturation magnetization Ms of the Co74Cr22Pt2TaLu film, the Co75Cr21Pt2TaLu film, the Co76Cr20Pt2TaLu film, the Co77Cr19Pt2TaLu film, the Co78Cr18Pt2TaLu film, and the Co80Cr17Ta3 film. 0277 By using a mono-pole/MR (magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium FFFF2 of the present invention and the conventional medium F1. The check conditions and the head characteristics were set in the same way as Example 5. 0278 FIG. 78 shows the medium noise dependency on the recording density for the FFFF2 of the present invention and the conventional medium F1. As is clear from FIG. 78, the conventional medium F1 shows a very high medium noise in the lower recording density, whereas in the medium FFFF2 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium F1. This is because the medium FFFF2 of the present invention includes a film having a preferable perpendicular magnetic anisotropy on the perpendicular magnetization film of Co80Cr17Ta3. Accordingly, in contrast to the conventional F1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0279 Note that the FeTaN film has no magnetic domain wall structure and the spike-shaped noise is not generated easily due to the magnetic domain wall movement. 0280 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 79 to FIG. 83. As is clear from FIG. 79 to FIG. 83, when the value R (Hk/4 pMs) is smaller than 1.4, medium noise cannot be improved (reduced) even if the film thickness is reduced. This is because if R is below 1.4, the perpendicular orientation characteristic is insufficient and it is impossible to sufficiently suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0281 On the other hand, if the film satisfies the relationship that R is equal to or greater than 1.4, the medium noise is reduced up to the film thickness 50 nm for all the film types. As has been described above, if a film satisfies the relationship that R is equal to or greater than 1.4, it is possible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. However, even if the film satisfies the aforementioned relationship, the medium noise reduction cannot be seen when the film thickness exceeds 50 nm. This is because of the fact that if the film thickness is too great, the orientation perpendicular to the film surface is deteriorated and it is impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0282 As has been described above, the recording medium FFFF2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the FFFF2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. Moreover, when the Co76Cr20Pt2TaLu film is provided under or both under and over the perpendicular magnetization film, similar results can be obtained because of the aforementioned reasons. Furthermore, film types other than the Co76Cr20Pt2TaLu film can also have similar results if the relationship that R is equal to or more than 1.4 is satisfied. 0283 Moreover, in the experiment using the ID/MR composite head used in Example 1 instead of the mono-pole composite head, similar results were obtained because of the aforementioned reasons.
EXAMPLE 10-2 0284 Media of Example 10-1 were prepared in the same way as in Example 9 except for that the CoxCr96.xPt2PrSr (7478) target was replaced by CoxCr96.xPt2PrSr (7478) target. The medium having the Co76Cr20Pt2PrSr film of 50 nm will be referred to as FFFF3 of the present invention. 0285 It should be noted we also prepared a medium having the Co76Cr20Pt2PrSr film and the Co80Cr17Ta3 film in the reversed order. That is, firstly, Co76Cr20Pt2PrSr film was formed on the substrate, and then the Co80Cr17Ta3 film was formed on the Co76Cr20Pt2PrSr film. 0286 FIG. 35 and FIG. 7 shows the perpendicular magnetic anisotropic energy Ku and saturation magnetization Ms of the Co74Cr22Pt2PrSr film, the Co75Cr21Pt2PrSr film, the Co76Cr20Pt2PrSr film, the C077Cr19Pt2PrSr film, the Co78CrPt2prSr film, and the Co80Cr17Ta3 film. 0287 By using a mono-pole/MR (magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium FFFF3 of the present invention and the conventional medium F1. The check conditions and the head characteristics were set in the same way as Example 5. 0288 FIG. 84 shows the medium noise dependency on the recording density for the FFFF3 of the present invention and the conventional medium F1. As is clear from FIG. 84, the conventional medium F1 shows a very high medium noise in the lower recording density, whereas in the medium FFFF3 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium F1. This is because the medium FFFF3 of the present invention includes a film having a preferable perpendicular magnetic anisotropy on the perpendicular magnetization film of Co80Cr17Ta3. Accordingly, in contrast to the conventional F1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0289 Note that the FeTaN film has no magnetic domain wall structure and the spike-shaped noise is not generated easily due to the magnetic domain wall movement. 0290 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 85 to FIG. 89. As is clear from FIG. 85 to FIG. 89, when the value R (Hk/4 pMs) is smaller than 1.4, medium noise cannot be improved (reduced) even if the film thickness is reduced. This is because if R is below 1.4, the perpendicular orientation characteristic is insufficient and it is impossible to sufficiently suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0291 On the other hand, if the film satisfies the relationship that R is equal to or greater than 1.4, the medium noise is reduced up to the film thickness 50 nm for all the film types. As has been described above, if a film satisfies the relationship that R is equal to or greater than 1.4, it is possible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. However, even if the film satisfies the aforementioned relationship, the medium noise reduction cannot be seen when the film thickness exceeds 50 nm. This is because of the fact that if the film thickness is too great, the orientation perpendicular to the film surface is deteriorated and it is impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0292 As has been described above, the recording medium FFFF3 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the FFFF3 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. Moreover, when the Co76Cr20Pt2PrSr film is provided under or both under and over the perpendicular magnetization film, similar results can be obtained because of the aforementioned reasons. Furthermore, film types other than the Co76Cr20Pt2TaLu film can also have similar results if the relationship that R is equal to or more than 1.4 is satisfied. 0293 Moreover, in the experiment using the ID/MR composite head used in Example 1 instead of the mono-pole composite head, similar results were obtained because of the aforementioned reasons.
EXAMPLE 11 0294 By using a 6-inch target of Co78Cr19Ta3 (%) for sputtering, 100 nm Co78Cr19Ta3 was formed on a substrate at temperature of 400 degrees centigrade. The film formation conditions were set as follows: initial vacuum degree 5107 mTorr, electric power 0.5 kW, argon gas pressure 4 mTorr, and film formation speed 3 nm/sed. 0295 On this film, an YCo5 film was formed by using an YCo5 target, while gradually changing the film thickness from 5 to 55 nm. Furthermore, on this YCo5 film, a C protection film was formed to have thickness of 10 nm. 0296 The medium having the YCo5 of 50 nm will be referred to as A2 of the present invention. On the contrary, the conventional medium having only the Co78Cr19Ta3 and no YCo5 will be referred to as a conventional medium A1. 0297 It should be noted that we also prepared a medium having the YCo5 film and the Co78Cr19Ta3 (at %) formed in the reversed order. That is, the YCo5 film was first formed on the substrate and the Co78Cr19Ta3 (at %) film was formed thereon. 0298 The perpendicular magnetic anisotropic energy Ku of the YCo5 film and the Co78Cr19Ta3 (at %) film were measured using a torque magnetometer. The results are shown in FIG. 90 and FIG. 7. As shown in FIG. 90 and FIG. 7, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 (at %) film is 9.0105, whereas the perpendicular magnetic anisotropic energy Ku of the YCo5 film is 5.0107, i.e., by far greater than the Co78Cr19Ta3 (at %) film. 0299 An ID/MR composite head was used to check the recording/reproduction characteristics of the medium A2 of the present invention and the conventional medium A1. The recording/reproduction conditions and the head used were same as the Example 1. 0300 FIG. 91 shows medium noise dependency on the recording density for the medium A2 of the present invention and the conventional medium A1. As is clear from this FIG. 91, the conventional medium Al has a very high noise in a lower recording density, whereas the medium A2 of the present invention has a suppressed noise in this low recording density region. This is because the medium A2 of the present invention has the perpendicular magnetic anisotropic energy Ku much higher than the Co78Cr19Ta3 (at %) and has the film having a preferable magnetic anisotropy on the perpendicular magnetization film of Co78Cr19Ta3 (at %). Accordingly, it is possible to effectively suppress generation of a reversed magnetic domain which may be caused in the vicinity of the surface of the perpendicular magnetization film. 0301 Next, the film thickness provided on the perpendicular magnetization film was gradually changed from 5 to 55 nm so as to check the medium noise values at the recording density 10 kFRPI. The check results are shown in FIG. 92. As is clear from FIG. 92, no output lowering can be seen up to the YCo5 film thickness of 50 nm, but when the film thickness exceeds 50 nm, there is no improvement (reduction) of the medium noise. This is because, if the YCo5 film thickness becomes too great, the YCo5 film orientation in the perpendicular direction is deteriorated, reducing the perpendicular magnetic anisotropic energy Ku. Accordingly it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0302 As has been described above, the medium A2 of the present invention has an excellent medium noise characteristic even in a low recording density region. That is, by using the medium A2 of the present invention, it is possible to suppress the medium noise increase in the low recording density region which has been the problem of the conventional perpendicular magnetic recording medium. 0303 Moreover, similar results can be obtained when the YCo5 film is provided under the perpendicular magnetization film or both under and over the perpendicular magnetization film.
EXAMPLE 12 0304 Media of Example 12 were prepared in the same way as Example 11, except for that a CeCo5 target was used instead of the YCo5 target. 0305 The medium having the CeCo, of 50 nm will be referred to as B2 of the present invention. 0306 Note that we also prepared media having CeC5 film and the Co78Cr19Ta3 film formed in the reversed order, i.e., was firstly formed on the substrate, and then the Co78CrTa3 film was formed thereon. 0307 The perpendicular magnetic anisotropic energy Ku of the CeCo5 film and the Co78Cr19Ta3 (at %) film were measured using a torque magnetometer. The results are shown in FIG. 90 and FIG. 7. As shown in FIG. 90 and FIG. 7, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 (at %) film is 9.0105, whereas the perpendicular magnetic anisotropic energy Ku of the CeCo5 film is 6.0107 erg/cc i.e., by far greater than the Co78Cr19Ta3 (at %) film. 0308 An ID/MR composite head was used to check the recording/reproduction characteristics of the medium B2 of the present invention and the conventional medium A1. The recording/reproduction conditions and the head used were same as the Example 11. 0309 FIG. 93 shows medium noise dependency on the recording density for the medium B2 of the present invention and the conventional medium A1. As is clear from this FIG. 93, the conventional medium Al has a very high noise in a lower recording density, whereas the medium B2 of the present invention has a suppressed noise in this low recording density region. This is because the medium B2 of the present invention has the perpendicular magnetic anisotropic energy Ku much higher than the Co78Cr19Ta3 (at %) and has the film having a preferable magnetic anisotropy on the perpendicular magnetization film of Co78Cr19Ta3 (at %). Accordingly, it is possible to effectively suppress generation of a reversed magnetic domain which may be caused in the vicinity of the surface of the perpendicular magnetization film. 0310 Next, the film thickness provided on the perpendicular magnetization film was gradually changed from 5 to 55 nm so as to check the medium noise values at the recording density 10 kFRPI. The check results are shown in FIG. 94. As is clear from FIG. 94, no output lowering can be seen up to the CeCo, film thickness of 50 nm, but when the film thickness exceeds 50 nm, there is no improvement (reduction) of the medium noise. This is because, if the CeCo5 film thickness becomes too great, the CeCo5 film orientation in the perpendicular direction is deteriorated, reducing the perpendicular magnetic anisotropic energy Ku. Accordingly it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0311 As has been described above, the medium B2 of the present invention has an excellent medium noise characteristic even in a low recording density region. That is, by using the medium B2 of the present invention, it is possible to suppress the medium noise increase in the low recording density region which has been the problem of the conventional perpendicular magnetic recording medium. 0312 Moreover, similar results can be obtained when the CeCo5 film is provided under the perpendicular magnetization film or both under and over the perpendicular magnetization film.
EXAMPLE 13 0313 Media of Example 13 were prepared in the same way as Example 11, except for that a SmCo5Ti target was used instead of the YCo5 target. 0314 The medium having the SmCo5Ti of 50 nm will be referred to as C2 of the present invention. 0315 Note that we also prepared media having SmCo5Ti film and the Co78Cr19Ta3 film formed in the reversed order, i.e., the SmCo5Ti film was formed firstly and then the Co78Cr19Ta3 film was formed thereon. 0316 The perpendicular magnetic anisotropic energy Ku of the SmCo5Ti film and the Co78Cr19Ta3 (at %) film were measured using a torque magnetometer. The results are shown in FIG. 90 and FIG. 7. As shown in FIG. 90 and FIG. 7, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 (at %) film is 9.0105, whereas the perpendicular magnetic anisotropic energy Ku of the SmCo5Ti film is 1.0108 erg/cc i.e., which is by far greater than the Co78Cr19Ta3 (at %) film. 0317 An ID/MR composite head was used to check the recording/reproduction characteristics of the medium C2 of the present invention and the conventional medium A1. The recording/reproduction conditions and the head used were same as the Example 11. 0318 FIG. 95 shows medium noise dependency on the recording density for the medium C2 of the present invention and the conventional medium A1. As is clear from this FIG. 95, the conventional medium A1 has a very high noise in a lower recording density region, whereas the medium C2 of the present invention has a suppressed noise in this low recording density region. This is because the medium C2 of the present invention has the perpendicular magnetic anisotropic energy Ku much higher than the Co78Cr19Ta3 (at %) and has the film having a preferable magnetic anisotropy on the perpendicular magnetization film of Co78Cr19Ta3 (at %) . Accordingly, it is possible to effectively suppress generation of a reversed magnetic domain which may be caused in the vicinity of the surface of the perpendicular magnetization film. 0319 Next, the film thickness provided on the perpendicular magnetization film was gradually changed from 5 to 55 nm so as to check the medium noise values at the recording density 10 kFRPI. The check results are shown in FIG. 96. As is clear from FIG. 96, no output lowering can be seen up to the SmCo5Ti film thickness of 50 nm, but when the film thickness exceeds 50 nm, there is no improvement (reduction) of the medium noise. This is because, if the SmCo5Ti film thickness becomes too great, the SmCo5Ti film orientation in the perpendicular direction is deteriorated, reducing the perpendicular magnetic anisotropic energy Ku. Accordingly it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0320 As has been described above, the medium C2 of the present invention has an excellent medium noise characteristic even in a low recording density region. That is, by using the medium C2 of the present invention, it is possible to suppress the medium noise increase in the low recording density region which has been the problem of the conventional perpendicular magnetic recording medium. 0321 Moreover, similar results can be obtained when the SmCo5 film is provided under the perpendicular magnetization film or both under and over the perpendicular magnetization film.
EXAMPLE 14 0322 Media of Example 14 were prepared in the same way as Example 11, except for that a LaCo5 target was used instead of the YCo5 target. 0323 The medium having the LaCo5 of 50 nm will be referred to as D2 of the present invention. 0324 Note that we also prepared media having LaCo5 film and the Co78Cr19Ta3 film formed in the reversed order, i.e., the LaCo5 film was formed firstly and then the Co78Cr19Ta3 film was formed thereon. 0325 The perpendicular magnetic anisotropic energy Ku of the LaCo5 film and the Co78Cr19Ta3 (at %) film were measured using a torque magnetometer. The results are shown in FIG. 90 and FIG. 7. As shown in FIG. 90 and FIG. 7, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 (at %) film is 9.0105 erg/cc whereas the perpendicular magnetic anisotropic energy Ku of the LaCo5 film is 6.0107 erg/cc i.e., which is by far greater than the Co78Cr19Ta3 (at %) film. 0326 An ID/MR composite head was used to check the recording/reproduction characteristics of the medium D2 of the present invention and the conventional medium A1. The recording/reproduction conditions and the head used were same as the Example 11. 0327 FIG. 97 shows medium noise dependency on the recording density for the medium D2 of the present invention and the conventional medium A1. As is clear from this FIG. 97, the conventional medium A1 has a very high noise in a lower recording density region, whereas the medium D2 of the present invention has a suppressed noise in this low recording density region. This is because the medium D2 of the present invention has the perpendicular magnetic anisotropic energy Ku much higher than the Co78Cr19Ta3 (at %) and has the film having a preferable magnetic anisotropy on the perpendicular magnetization film of Co78Cr19Ta3 (at %). Accordingly, it is possible to effectively suppress generation of a reversed magnetic domain which may be caused in the vicinity of the surface of the perpendicular magnetization film. 0328 Next, the film thickness provided on the perpendicular magnetization film was gradually changed from 5 to 55 nm so as to check the medium noise values at the recording density 10 kFRPI. The check results are shown in FIG. 98. As is clear from FIG. 98, no output lowering can be seen up to the LaCo5 film thickness of 50 nm, but when the film thickness exceeds 50 nm, there is no improvement (reduction) of the medium noise. This is because, if the LaCo5 film thickness becomes too great, the LaCo5 film orientation in the perpendicular direction is deteriorated, reducing the perpendicular magnetic anisotropic energy Ku. Accordingly it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0329 As has been described above, the medium D2 of the present invention has an excellent medium noise characteristic even in a low recording density region. That is, by using the medium D2 of the present invention, it is possible to suppress the medium noise increase in the low recording density region which has been the problem of the conventional perpendicular magnetic recording medium. 0330 Moreover, similar results can be obtained when the LaCo5 film is provided under the perpendicular magnetization film or both under and over the perpendicular magnetization film.
EXAMPLE 15 0331 Media of Example 15 were prepared in the same way as Example 11, except for that a PrCo5 target was used instead of the YCo5 target. 0332 The medium having the PrCo5 of 50 nm will be referred to as E2 of the present invention. 0333 Note that we also prepared media having PrCo5 film and the Co78Cr19Ta3 (at %) film formed in the reversed order, i.e., the PrCo5 film was formed firstly and then the Co78Cr19Ta3 film was formed thereon. 0334 The perpendicular magnetic anisotropic energy Ku of the PrCo5 film and the Co78Cr19Ta3 (at %) film were measured using a torque magnetometer. The results are shown in FIG. 90 and FIG. 7. As shown in FIG. 90 and FIG. 7, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 (at %) film is 9.0105 erg/cc whereas the perpendicular magnetic anisotropic energy Ku of the PrCo5 film is 8.0107 erg/cc i.e., which is by far greater than the Co78Cr19Ta3 (at %) film. 0335 An ID/MR composite head was used to check the recording/reproduction characteristics of the medium E2 of the present invention and the conventional medium A1. The recording/reproduction conditions and the head used were identical to those of the Example 11. 0336 FIG. 99 shows medium noise dependency on the recording density for the medium E2 of the present invention and the conventional medium A1. As is clear from this FIG. 99, the conventional medium A1 has a very high noise in a lower recording density region, whereas the medium E2 of the present invention has a suppressed noise in this low recording density region. This is because the medium E2 of the present invention has the perpendicular magnetic anisotropic energy Ku much higher than the Co78Cr19Ta3 (at %) and has the film having a preferable magnetic anisotropy on the perpendicular magnetization film of Co78Cr19Ta3 (at %). Accordingly, it is possible to effectively suppress generation of a reversed magnetic domain which may be caused in the vicinity of the surface of the perpendicular magnetization film. 0337 Next, the film thickness provided on the perpendicular magnetization film was gradually changed from 5 to 55 nm so as to check the medium noise values at the recording density 10 kFRPI The check results are shown in FIG. 100. As is clear from FIG. 100, no output lowering can be seen up to 50 nm thickness of the PrCo5, but when the film thickness exceeds 50 nm, there is no improvement (reduction) of the medium noise. This is because, if the PrCo5 film thickness becomes too great, the PrCo5 film orientation in the perpendicular direction is deteriorated, reducing the perpendicular magnetic anisotropic energy Ku. Accordingly it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0338 As has been described above, the medium E2 of the present invention has an excellent medium noise characteristic even in a low recording density region. That is, by using the medium E2 of the present invention, it is possible to suppress the medium noise increase in the low recording density region which has been the problem of the conventional perpendicular magnetic recording medium. 0339 Moreover, similar results can be obtained when the PrCo5 film is provided under the perpendicular magnetization film or both under and over the perpendicular magnetization film.
EXAMPLE 16 0340 Media of Example 16 were prepared in the same way as Example 11, except for that a Y2Co17 target was used instead of the YCo5 target. 0341 The medium having the Y2Co17 of 50 nm thickness will be referred to as F2 of the present invention. 0342 Note that we also prepared media having Y2Co17 film and the Co78Cr19Ta3 (at %) film formed in the reversed order, i.e., the Y2Co17 film was formed firstly and then the Co78Cr19Ta3 film was formed thereon. 0343 The perpendicular magnetic anisotropic energy Ku of the Y2Co17 film and the Co78Cr19Ta3 (at %) film were measured using a torque magnetometer. The results are shown in FIG. 90 and FIG. 7. As shown in FIG. 90 and FIG. 7, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 (at %) film is 9.0105 erg/cc whereas the perpendicular magnetic anisotropic energy Ku of the Y2Co17 film is 2.0107 erg/cc i.e., which is by far greater than the Co78Cr19Ta3 (at %) film. 0344 An ID/MR composite head was used to check the recording/reproduction characteristics of the medium F2 of the present invention and the conventional medium A1. The recording/reproduction conditions and the head used were identical to those of the Example 11. 0345 FIG. 101 shows medium noise dependency on the recording density for the medium F2 of the present invention and the conventional medium A1. As is clear from this FIG. 101, the conventional medium A1 has a very high noise in a lower recording density region, whereas the medium F2 of the present invention has a suppressed noise in this low recording density region. This is because the medium F2 of the present invention has the perpendicular magnetic anisotropic energy Ku much higher than the Co78Cr19Ta3 (at %) and has the film having a preferable magnetic anisotropy on the perpendicular magnetization film of Co78Cr19Ta3 (at %). Accordingly, it is possible to effectively suppress generation of a reversed magnetic domain which may be caused in the vicinity of the surface of the perpendicular magnetization film. 0346 Next, the film thickness provided on the perpendicular magnetization film was gradually changed from 5 to 55 nm so as to check the medium noise values at the recording density 10 kFRPI. The check results are shown in FIG. 102. As is clear from FIG. 102, no output lowering can be seen up to 50 nm thickness of the Y2Co17, but when the film thickness exceeds 50 nm there is no improvement (reduction) of the medium noise. This is because, if the Y2Co17 film thickness becomes too great, the Y2Co17 film orientation in the perpendicular direction is deteriorated, reducing the perpendicular magnetic anisotropic energy Ku. Accordingly it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0347 As has been described above, the medium F2 of the present invention has an excellent medium noise characteristic even in a low recording density region. That is, by using the medium F2 of the present invention, it is possible to suppress the medium noise increase in the low recording density region which has been the problem of the conventional perpendicular magnetic recording medium. 0348 Moreover, similar results can be obtained when the Y2Co17 film is provided under the perpendicular magnetization film or both under and over the perpendicular magnetization film.
EXAMPLE 17 0349 Media of Example 17 were prepared in the same way as Example 16, except for that a Ce2Co17 target was used instead of the Y2Co17 target. 0350 The medium having the Ce2Co17 of 50 nm thickness will be referred to as G2 of the present invention. 0351 Note that we also prepared media having Y2Co17 film and the Co78Cr19Ta3 (at %) film formed in the reversed order, i.e., the Y2Co17 film was formed firstly and then the Co78Cr19Ta3 (at %) film was formed thereon. 0352 The perpendicular magnetic anisotropic energy Ku of the Ce2Co17 film and the Co78Cr19Ta3 (at %) film were measured using a torque magnetometer. The results are shown in FIG. 90 and FIG. 7. As shown in FIG. 90 and FIG. 7, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 (at %) film is 9.0105 erg/cc whereas the perpendicular magnetic anisotropic energy Ku of the Ce2Co17 film is 3.0107 erg/cc i.e., which is by far greater than the Co78Cr19Ta3 (at %) film. 0353 An ID/MR composite head was used to check the recording/reproduction characteristics of the medium G2 of the present invention and the conventional medium A1. The recording/reproduction conditions and the head used were identical to those of the Example 11. 0354 FIG. 103 shows medium noise dependency on the recording density for the medium G2 of the present invention and the conventional medium A1. As is clear from this FIG. 103, the conventional medium A1 has a very high noise in a lower recording density region, whereas the medium G2 of the present invention has a suppressed noise in this low recording density region. This is because the medium G2 of the present invention has the perpendicular magnetic anisotropic energy Ku much higher than the Co78Cr19Ta3 (at %) and has the film having a preferable magnetic anisotropy on the perpendicular magnetization film of Co78Cr19Ta3 (at %). Accordingly, it is possible to effectively suppress generation of a reversed magnetic domain which may be caused in the vicinity of the surface of the perpendicular magnetization film. 0355 Next, the film thickness provided on the perpendicular magnetization film was gradually changed from 5 to 55 nm so as to check the medium noise values at the recording density 10 kFRPI. The check results are shown in FIG. 104. As is clear from FIG. 104, no output lowering can be seen up to 50 nm thickness of the Ce2Co17, but when the film thickness exceeds 50 nm, there is no improvement (reduction) of the medium noise. This is because, if the Ce2Co17 film thickness becomes too great, the Ce2Co17 film orientation in the perpendicular direction is deteriorated, reducing the perpendicular magnetic anisotropic energy Ku. Accordingly it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0356 As has been described above, the medium G2 of the present invention has an excellent medium noise characteristic even in a low recording density region. That is, by using the medium G2 of the present invention, it is possible to suppress the medium noise increase in the low recording density region which has been the problem of the conventional perpendicular magnetic recording medium. 0357 Moreover, similar results can be obtained when the Ce2Co17 film is provided under the perpendicular magnetization film or both under and over the perpendicular magnetization film.
EXAMPLE 18 0358 Media of Example 18 were prepared in the same way as Example 16, except for that a Sm2Co17Ti target was used instead of the Y2Co17 target. 0359 The medium having the Sm2Co17Ti of 50 nm thickness will be referred to as H2 of the present invention. 0360 Note that we also prepared media having Sm2Co17Ti film and the Co78Cr19Ta3 (at %) film formed in the reversed order, i.e., the Sm2Co17Ti film was formed firstly and then the Co78Cr19Ta3 (at %) film was formed thereon. 0361 The perpendicular magnetic anisotropic energy Ku of the Sm2Co17Ti film and the Co78Cr19Ta3 (at %) film were measured using a torque magnetometer. The results are shown in FIG. 90 and FIG. 7. As shown in FIG. 90 and FIG. 7, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 (at %) film is 9.0105 erg/cc whereas the perpendicular magnetic anisotropic energy Ku of the Sm2Co17Ti film is 4.2107 erg/cc i.e., which is by far greater than the Co78Cr19Ta3 (at %) film. 0362 An ID/MR composite head was used to check the recording/reproduction characteristics of the medium H2 of the present invention and the conventional medium A1. The recording/reproduction conditions and the head used were identical to those of the Example 11. 0363 FIG. 105 shows medium noise dependency on the recording density for the medium H2 of the present invention and the conventional medium A1. As is clear from this FIG. 105, the conventional medium A1 has a very high noise in a lower recording density region, whereas the medium H2 of the present invention has a suppressed noise in this low recording density region. This is because the medium H2 of the present invention has the perpendicular magnetic anisotropic energy Ku much higher than the Co78Cr19Ta3 (at %) and has the film having a preferable magnetic anisotropy on the perpendicular magnetization film of Co78Cr19Ta3 (at %). Accordingly, it is possible to effectively suppress generation of a reversed magnetic domain which may be caused in the vicinity of the surface of the perpendicular magnetization film. 0364 Next, the film thickness provided on the perpendicular magnetization film was gradually changed from 5 to 55 nm so as to check the medium noise values at the recording density 10 kFRPI. The check results are shown in FIG. 106. As is clear from FIG. 106, no output lowering can be seen up to 50 nm thickness of the Sm2Co17Ti, but when the film thickness exceeds 50 nm, there is no improvement (reduction) of the medium noise. This is because, if the Sm2Co17Ti film thickness becomes too great, the Sm2Co17Ti film orientation in the perpendicular direction is deteriorated, reducing the perpendicular magnetic anisotropic energy Ku. Accordingly it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0365 As has been described above, the medium H2 of the present invention has an excellent medium noise characteristic even in a low recording density region. That is, by using the medium H2 of the present invention, it is possible to suppress the medium noise increase in the low recording density region which has been the problem of the conventional perpendicular magnetic recording medium. 0366 Moreover, similar results can be obtained when the Sm2Co17Ti film is provided under the perpendicular magnetization film or both under and over the perpendicular magnetization film.
EXAMPLE 19 0367 Media of Example 19 were prepared in the same way as Example 16, except for that a La2Co17 target was used instead of the Y2Co17 target. 0368 The medium having the La2Co17 of 50 nm thickness will be referred to as J2 of the present invention. 0369 Note that we also prepared media having La2Co17 film and the Co78Cr19Ta3 (at %) film formed in the reversed order, i.e., the La2Co17 film was formed firstly on the substrate and then the Co78Cr19Ta3 (at %) film was formed thereon. 0370 The perpendicular magnetic anisotropic energy Ku of the La2Co17 film and the Co78Cr19Ta3 (at %) film were measured using a torque magnetometer. The results are shown in FIG. 90 and FIG. 7. As shown in FIG. 90 and FIG. 7, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 (at %) film is 9.0105 erg/cc whereas the perpendicular magnetic anisotropic energy Ku of the La2Co17 film is 3.5107 erg/cc i.e., which is by far greater than the Co78Cr19Ta3 (at %) film. 0371 An ID/MR composite head was used to check the recording/reproduction characteristics of the medium J2 of the present invention and the conventional medium A1. The recording/reproduction conditions and the head used were identical to those of the Example 11. 0372 FIG. 107 shows medium noise dependency on the recording density for the medium J2 of the present invention and the conventional medium A1. As is clear from this FIG. 107, the conventional medium A1 has a very high noise in a lower recording density region, whereas the medium J2 of the present invention has a suppressed noise in this low recording density region. This is because the medium J2 of the present invention has the perpendicular magnetic anisotropic energy Ku much higher than the Co78Cr19Ta3 (at %) and has the film having a preferable magnetic anisotropy on the perpendicular magnetization film of Co78Cr19Ta3 (at %) . Accordingly, it is possible to effectively suppress generation of a reversed magnetic domain which may be caused in the vicinity of the surface of the perpendicular magnetization film. 0373 Next, the film thickness provided on the perpendicular magnetization film was gradually changed from 5 to 55 nm so as to check the medium noise values at the recording density 10 kFRPI. The check results are shown in FIG. 108. As is clear from FIG. 108, no output lowering can be seen up to 50 nm thickness of the La2Co17, but when the film thickness exceeds 50 nm, there is no improvement (reduction) of the medium noise. This is because, if the La2Co17 film thickness becomes too great, the La2Co17 film orientation in the perpendicular direction is deteriorated, reducing the perpendicular magnetic anisotropic energy Ku. Accordingly it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0374 As has been described above, the medium J2 of the present invention has an excellent medium noise characteristic even in a low recording density region. That is, by using the medium J2 of the present invention, it is possible to suppress the medium noise increase in the low recording density region which has been the problem of the conventional perpendicular magnetic recording medium. 0375 Moreover, similar results can be obtained when the La2Co17 film is provided under the perpendicular magnetization film or both under and over the perpendicular magnetization film.
EXAMPLE 20 0376 Media of Example 20 were prepared in the same way as Example 16, except for that a Pr2Co17 target was used instead of the Y2Co17 target. 0377 The medium having the Pr2Co17 of 50 nm thickness will be referred to as K2 of the present invention. 0378 Note that we also prepared media having Pr2Co17 film and the Co78Cr19Ta3 (at %) film formed in the reversed order, i.e., the Pr2Co17 film was formed firstly on the substrate and then the Co78Cr19Ta3 (at %) film was formed thereon. 0379 The perpendicular magnetic anisotropic energy Ku of the La2Co17 film and the Co78Cr19Ta3 (at %) film were measured using a torque magnetometer. The results are shown in FIG. 90 and FIG. 7. As shown in FIG. 90 and FIG. 7, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 (at %) film is 9.0105 erg/cc whereas the perpendicular magnetic anisotropic energy Ku of the Pr2Co17 film is 2.7107 erg/cc i.e., which is by far greater than the Co78Cr19Ta3 (at %) film. 0380 An ID/MR composite head was used to check the recording/reproduction characteristics of the medium K2 of the present invention and the conventional medium A1. The recording/reproduction conditions and the head used were identical to those of the Example 11. 0381 FIG. 109 shows medium noise dependency on the recording density for the medium K2 of the present invention and the conventional medium A1. As is clear from this FIG. 109, the conventional medium A1 has a very high noise in a lower recording density region, whereas the medium K2 of the present invention has a suppressed noise in this low recording density region. This is because the medium K2 of the present invention has the perpendicular magnetic anisotropic energy Ku much higher than the Co78Cr19Ta3 (at %) and has the film having a preferable magnetic anisotropy on the perpendicular magnetization film of Co78Cr19Ta3 (at %). Accordingly, it is possible to effectively suppress generation of a reversed magnetic domain which may be caused in the vicinity of the surface of the perpendicular magnetization film. 0382 Next, the film thickness provided on the perpendicular magnetization film was gradually changed from 5 to 55 nm so as to check the medium noise values at the recording density 10 kFRPI. The check results are shown in FIG. 110. As is clear from FIG. 110, no output lowering can be seen up to 50 nm thickness of the Pr2Co17, but when the film thickness exceeds 50 nm, there is no improvement (reduction) of the medium noise. This is because, if the Pr2Co17 film thickness becomes too great, the Pr2Co17 film orientation in the perpendicular direction is deteriorated, reducing the perpendicular magnetic anisotropic energy Ku. Accordingly it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0383 As has been described above, the medium K2 of the present invention has an excellent medium noise characteristic even in a low recording density region. That is, by using the medium K2 of the present invention, it is possible to suppress the medium noise increase in the low recording density region which has been the problem of the conventional perpendicular magnetic recording medium. 0384 Moreover, similar results can be obtained when the Pr2Co17 film is provided under the perpendicular magnetization film or both under and over the perpendicular magnetization film.
EXAMPLE 21 0385 Media of Example 21 were prepared in the same way as Example 11, except for that the YCo5 target was replaced by a Ba ferrite, i.e., a BaFe12O19 target. 0386 The medium having the BaFe12O19 of 50 nm thickness will be referred to as L2 of the present invention. 0387 Note that we also prepared media having BaFe12O19 film and the Co78Cr19Ta3 (at %) film formed in the reversed order, i.e., the BaFe12O19 film was formed firstly on the substrate and then the Co79Cr19Ta3 (at %) film was formed thereon. 0388 The perpendicular magnetic anisotropic energy Ku of the BaFe12O19 film and the Co78Cr19Ta3 (at %) film were measured using a torque magnetometer. The results are shown in FIG. 111 and FIG. 7. As shown in FIG. 111 and FIG. 7, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 (at %) film is 9.0105 erg/cc whereas the perpendicular magnetic anisotropic energy Ku of the BaFe12O19 film is 3.3106 erg/cc i.e., which is by far greater than the Ku value of the Co78Cr19Ta3 (at %) film. 0389 An ID/MR composite head was used to check the recording/reproduction characteristics of the medium L2 of the present invention and the conventional medium A1. The recording/reproduction conditions and the head used were identical to those of the Example 11. 0390 FIG. 112 shows medium noise dependency on the recording density for the medium L2 of the present invention and the conventional medium A1. As is clear from this FIG. 112, the conventional medium A1 has a very high noise in a lower recording density region, whereas the medium L2 of the present invention has a suppressed noise in this low recording density region. This is because the medium L2 of the present invention has the perpendicular magnetic anisotropic energy Ku much higher than the Co78Cr19Ta3 (at %) and has the film having a preferable magnetic anisotropy on the perpendicular magnetization film of Co78Cr19Ta3 (at %). Accordingly, it is possible to effectively suppress generation of a reversed magnetic domain which may be caused in the vicinity of the surface of the perpendicular magnetization film. 0391 Next, the film thickness provided on the perpendicular magnetization film was gradually changed from 5 to 55 nm so as to check the medium noise values at the recording density 10 kFRPI. The check results are shown in FIG. 113. As is clear from FIG. 113, no output lowering can be seen up to 50 nm thickness of the BaFe12O19, but when the film thickness exceeds 50 nm, there is no improvement (reduction) of the medium noise. This is because, if the BaFe12O19 film thickness becomes too great, the BaFe12O19 film orientation in the perpendicular direction is deteriorated, reducing the perpendicular magnetic anisotropic energy Ku. Accordingly it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0392 As has been described above, the medium L2 of the present invention has an excellent medium noise characteristic even in a low recording density region. That is, by using the medium L2 of the present invention, it is possible to suppress the medium noise increase in the low recording density region which has been the problem of the conventional perpendicular magnetic recording medium. 0393 Moreover, similar results can be obtained when the BaFe12O19 film is provided under the perpendicular magnetization film or both under and over the perpendicular magnetization film.
EXAMPLE 22 0394 Media of Example 22 were prepared in the same way as Example 11, by using another Ba ferrite, i.e., a BaFe18O27 target in stead of the BaFe12O19 target used in Example 21. 0395 The medium having the BaFe18O27 of 50 nm thickness will be referred to as M2 of the present invention. 0396 Note that we also prepared media having BaFe18O27 film and the Co78Cr19Ta3 (at %) film formed in the reversed order, i.e., the BaFe18O27 film was formed firstly on the substrate and then the Co78Cr19Ta3 (at %) film was formed thereon. 0397 The perpendicular magnetic anisotropic energy Ku of the BaFe18O27 film and the Co78Cr13Ta3 (at %) film were measured using a torque magnetometer. The results are shown in FIG. 111 and FIG. 7. As shown in FIG. 111 and FIG. 7, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 (at %) film is 9.0105 erg/cc whereas the vertica magnetic anisotropic energy Ku of the BaFe18O27 film is 3.0106 erg/cc i.e., which is by far greater than the Ku value of the Co78Cr19Ta3 (at %) film. 0398 An ID/MR composite head was used to check the recording/reproduction characteristics of the medium M2 of the present invention and the conventional medium A1. The recording/reproduction conditions and the head used were identical to those of the Example 11. 0399 FIG. 114 shows medium noise dependency on the recording density for the medium M2 of the present invention and the conventional medium A1. As is clear from this FIG. 114, the conventional medium A1 has a very high noise in a lower recording density region, whereas the medium M2 of the present invention has a suppressed noise in this low recording density region. This is because the medium M2 of the present invention has the perpendicular magnetic anisotropic energy Ku much higher than the Co78Cr19Ta3 (at %) and has the film having a preferable magnetic anisotropy on the perpendicular magnetization film of Co78Cr19Ta3 (at %). Accordingly, it is possible to effectively suppress generation of a reversed magnetic domain which may be caused in the vicinity of the surface of the perpendicular magnetization film. 0400 Next, the film thickness provided on the perpendicular magnetization film was gradually changed from 5 to 55 nm so as to check the medium noise values at the recording density 10 kFRPI. The check results are shown in FIG. 115. As is clear from FIG. 115, no output lowering can be seen up to 50 nm thickness of the BaFe18Co27, but when the film thickness exceeds 50 nm, there is no improvement (reduction) of the medium noise. This is because, if the BaFe18O27 film thickness becomes too great, the BaFe18O27 film orientation in the perpendicular direction is deteriorated, reducing the perpendicular magnetic anisotropic energy Ku. Accordingly it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0401 As has been described above, the medium M2 of the present invention has an excellent medium noise characteristic even in a low recording density region. That is, by using the medium M2 of the present invention, it is possible to suppress the medium noise increase in the low recording density region which has been the problem of the conventional perpendicular magnetic recording medium. 0402 Moreover, similar results can be obtained when the BaFe18O27 film is provided under the perpendicular magnetization film or both under and over the perpendicular magnetization film.
EXAMPLE 23 0403 Media of Example 23 were prepared in the same way as Example 11, using a Sr ferrite target, i.e., a SrFe12O19 target in stead of the BaFe12O19 target used in Example 21. The medium having the SrFe12O19 of 50 nm thickness will be referred to as N2 of the present invention. 0404 Note that we also prepared media having SrFe12O19 film and the Co78Cr19Ta3 (at %) film formed in the reversed order, i.e., the BaFe12O19 film was formed firstly on the substrate and then the Co78Cr19Ta3 (at %) film was formed thereon. 0405 The perpendicular magnetic anisotropic energy Ku of the SrFe12O19 film and the Co78Cr19Ta3 (at %) film were measured using a torque magnetometer. The results are shown in FIG. 111 and FIG. 7. As shown in FIG. 111 and FIG. 7, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 (at %) film is 9.0105 erg/cc whereas the vertica magnetic anisotropic energy Ku of the SrFe12O19 film is 3.4106 erg/cc i.e., which is by far greater than the. Ku value of the Co78Cr19Ta3 (at %) film. 0406 An ID/MR composite head was used to check the recording/reproduction characteristics of the medium N2 of the present invention and the conventional medium A1. The recording/reproduction conditions and the head used were identical to those of the Example 11. 0407 FIG. 116 shows medium noise dependency on the recording density for the medium N2 of the present invention and the conventional medium A1. As is clear from this FIG. 116, the conventional medium A1 has a very high noise in a lower recording density region, whereas the medium N2 of the present invention has a suppressed noise in this low recording density region. This is because the medium N2 of the present invention has the perpendicular magnetic anisotropic energy Ku much higher than the Co78Cr19Ta3 (at %) and has the film having a preferable magnetic anisotropy on the perpendicular magnetization film of Co78Cr19Ta3 (at %). Accordingly, it is possible to effectively suppress generation of a reversed magnetic domain which may be caused in the vicinity of the surface of the perpendicular magnetization film. 0408 Next, the film thickness provided on the perpendicular magnetization film was gradually changed from 5 to 55 nm so as to check the medium noise values at the recording density 10 kFRPI. The check results are shown in FIG. 117. As is clear from FIG. 117, no output lowering can be seen up to 50 nm thickness of the SrFe12Co19, but when the film thickness exceeds 50 nm, there is no improvement (reduction) of the medium noise. This is because, if the SrFe12O19 film thickness becomes too great, the SrFe12O19 film orientation in the perpendicular direction is deteriorated, reducing the perpendicular magnetic anisotropic energy Ku. Accordingly it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0409 As has been described above, the medium N2 of the present invention has an excellent medium noise characteristic even in a low recording density region. That is, by using the medium N2 of the present invention, it is possible to suppress the medium noise increase in the low recording density region which has been the problem of the conventional perpendicular magnetic recording medium. 0410 Moreover, similar results can be obtained when the SrFe12O19 film is provided under the perpendicular magnetization film or both under and over the perpendicular magnetization film.
EXAMPLE 24 0411 Media of Example 24 were prepared in the same way as Example 11, using another Sr ferrite target, i.e., a SrFe18O27 target in stead of the SrFe12O19target used in Example 23. The medium having the SrFe18O27 of 50 nm thickness will be referred to as P2 of the present invention. 0412 Note that we also prepared media having SrFe18O27 film and the Co78Cr19Ta3 (at %) film formed in the reversed order, i.e., the BaFe18O27 film was formed firstly on the substrate and then the Co78Cr19Ta3 (at %) film was formed thereon. 0413 The perpendicular magnetic anisotropic energy Ku of the SrFe18O27 film and the Co78Cr19Ta3 (at %) film were measured using a torque magnetometer. The results are shown in FIG. 111 and FIG. 7. As shown in FIG. 111 and FIG. 7, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 (at %) film is 9.0105 erg/cc whereas the vertica magnetic anisotropic energy Ku of the SrFe18O27 film is 3.1106 erg/cc i.e., which is by far greater than the Ku value of the Co78Cr19Ta3 (at %) film. 0414 An ID/MR composite head was used to check the recording/reproduction characteristics of the medium P2 of the present invention and the conventional medium A1. The recording/reproduction conditions and the head used were identical to those of the Example 11. 0415 FIG. 118 shows medium noise dependency on the recording density for the medium P2 of the present invention and the conventional medium A1. As is clear from this FIG. 118, the conventional medium A1 has a very high noise in a lower recording density region, whereas the medium P2 of the present invention has a suppressed noise in this low recording density region. This is because the medium P2 of the present invention has the perpendicular magnetic anisotropic energy Ku much higher than the Co78Cr19Ta3 (at %) and has the film having a preferable magnetic anisotropy on the perpendicular magnetization film of Co78Cr19Ta3 (at %). Accordingly, it is possible to effectively suppress generation of a reversed magnetic domain which may be caused in the vicinity of the surface of the perpendicular magnetization film. 0416 Next, the film thickness provided on the perpendicular magnetization film was gradually changed from 5 to 55 nm so as to check the medium noise values at the recording density 10 kFRPI. The check results are shown in FIG. 119. As is clear from FIG. 119, no output lowering can be seen up to 50 nm thickness of the SrFe18Co27, but when the film thickness exceeds 50 nm, there is no improvement (reduction) of the medium noise. This is because, if the SrFe12O19 film thickness becomes too great, the SrFe12O19 film orientation in the perpendicular direction is deteriorated, reducing the perpendicular magnetic anisotropic energy Ku. Accordingly it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0417 As has been described above, the medium P2 of the present invention has an excellent medium noise characteristic even in a low recording density region. That is, by using the medium P2 of the present invention, it is possible to suppress the medium noise increase in the low recording density region which has been the problem of the conventional perpendicular magnetic recording medium. 0418 Moreover, similar results can be obtained when the SrFe18O27 film is provided under the perpendicular magnetization film or both under and over the perpendicular magnetization film.
EXAMPLE 25 0419 Media of Example 25 were prepared in the same way as Example 11 except for that the YCo5 target was replaced Pt50Co50 (at %) target. The medium having the Pt50Co50 of 50 nm thickness will be referred to as Q2 of the present invention. 0420 Note that we also prepared media having Pt50Co50 film and the Co78Cr19Ta3 (at %) film formed in the reversed order, i.e., the Pt50Co50 film was formed firstly on the substrate and then the Co78Cr19Ta3 (at %) film was formed thereon. 0421 The perpendicular magnetic anisotropic energy Ku of the Pt50Co50 (at %) film and the Co78Cr19Ta3 (at %) film were measured using a torque magnetometer. The results are shown in FIG. 111 and FIG. 7. As shown in FIG. 111 and FIG. 7, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 (at %) film is 9.0105 erg/cc whereas the vertica magnetic anisotropic energy Ku of the Pt50Co50 film is 1.0107 erg/cc i.e., which is by far greater than the Ku value of the Co78Cr19Ta3 (at %) film. 0422 An ID/MR composite head was used to check the recording/reproduction characteristics of the medium Q2 of the present invention and the conventional medium A1. The recording/reproduction conditions and the head used were identical to those of the Example 11. 0423 FIG. 120 shows medium noise dependency on the recording density for the medium Q2 of the present invention and the conventional medium A1. As is clear from this FIG. 120, the conventional medium A1 has a very high noise in a lower recording density region, whereas the medium Q2 of the present invention has a suppressed noise in this low recording density region. This is because the medium Q2 of the present invention has the perpendicular magnetic anisotropic energy Ku much higher than the Co78Cr19Ta3 (at %) and has the film having a preferable magnetic anisotropy on the perpendicular magnetization film of Co78Cr19Ta3 (at %). Accordingly, it is possible to effectively suppress generation of a reversed magnetic domain which may be caused in the vicinity of the surface of the perpendicular magnetization film. 0424 Next, the film thickness provided on the perpendicular magnetization film was gradually changed from 5 to 55 nm so as to check the medium noise values at the recording density 10 kFRPI. The check results are shown in FIG. 121. As is clear from FIG. 121, no output lowering can be seen up to 50 nm thickness of the Pt50Co50, but when the film thickness exceeds 50 nm there is no improvement (reduction) of the medium noise. This is because, if the Pt50Co50 film thickness becomes too great, the Pt50Co50 film orientation in the perpendicular direction is deteriorated, reducing the perpendicular magnetic anisotropic energy Ku. Accordingly it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0425 As has been described above, the medium Q2 of the present invention has an excellent medium noise characteristic even in a low recording density region. That is, by using the medium Q2 of the present invention, it is possible to suppress the medium noise increase in the low recording density region which has been the problem of the conventional perpendicular magnetic recording medium. 0426 Moreover, similar results can be obtained when the Pt50Co50 film is provided under the perpendicular magnetization film or both under and over the perpendicular magnetization film.
EXAMPLE 26 0427 Using a 6-inch FeSiAl target for sputtering, a FeSiAl film was formed with a thickness of 500 nm on 2.5-inch substrates. The film formation conditions were as follows: initial vacuum degree 5107 mTorr; electric power 0.5 kw; argon gas pressure 4 mTorr; film formation speed 3 nm/sec. 0428 Then, each of the FeSiAl films on the substrates at temperature of 400 degrees centigrade was covered by 100 nm of Co78Cr19Ta3 (at %) film formed by using a Co78Cr19Ta3 target under the same film formation conditions as FeSiAl. 0429 Next, the Co78Cr19Ta3 films were respectively covered by 10 to 55 nm thickness of YCo5 films. Furthermore, a C (carbon) protection film of 10 nm was formed to cover each of the aforementioned films. 0430 The medium having the 50 nm of YCo5 will be referred to as AA2 of the present invention. 0431 On the other hand, the medium having no YCo5 film will be referred to as a conventional medium (comparative example) B1. 0432 It should be noted we also prepared a medium having the YCo5 film and the Co78Cr19Ta3 film in the reversed order. That is, firstly, YCo5 film was formed on the substrate, and then the Co78Cr19Ta3 film was formed on the YCo5 film. 0433 As has been shown in Example 11, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 film is 9.0105 erg/cc, whereas the perpendicular magnetic anisotropic energy of the YCo5 film is 5.0107 erg/cc, which is by far greater than the Ku of the Co78Cr19Ta3 film. (See FIG. 90 and FIG. 7) 0434 By using a mono-pole/MR (magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium AA2 of the present invention and the conventional medium B1. The check conditions were set as follows: mono-pole head recording track width 4 micrometers, the main magnetic pole film thickness 0.4 micrometers, reproduction track width 3 micrometers, and reproduction gap length 0.32 micrometers. Note that the check was performed under the condition of: recording current 10 mAop, sense current 12 mA, peripheral velocity 12.7 m/s, and floating amount 45 nm. 0435 FIG. 122 shows the medium noise dependency on the recording density for the AA2 of the present invention and the conventional medium B1. As is clear from FIG. 122, the conventional medium B1 shows a very high medium noise in the lower recording density, whereas in the medium AA2 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium E1. This is because the medium AA2 of the present invention includes the YCo5 film having much higher perpendicular magnetic anisotropy Ku than the Co78Cr19Ta3 and the film is formed on the Co78Cr19Ta3 film. Accordingly, in contrast to the conventional B1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. Note that the FeSiAl film has no magnetic domain wall structure and the spike-shaped noise is not generated easily due to the magnetic domain wall movement. 0436 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 123. As is clear from FIG. 123, no output lowering can be seen up to 50 nm of the YCo5 film. When the YCo5 film thickness exceeds 50 nm, the medium noise cannot be improved (reduced). This is because if YCo5 film thickness becomes too large, YCo5 film orientation in the perpendicular direction to the film surface is deteriorated and the perpendicular magnetic anisotropic energy Ku becomes smaller. Thus, it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the perpendicular magnetization film. 0437 As has been described above, the recording medium AA2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the AA2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. 0438 Moreover, when the YCO5 film was provided under or both under and over the perpendicular magnetization film, similar results were obtained because of the aforementioned reasons. 0439 Furthermore, in the experiment using the ID/MR composite head used in Example 1 instead of the mono-pole composite head, similar results were obtained because of the aforementioned reasons.
EXAMPLE 27 0440 Media of Example 27 was prepared in the same way as Example 26, except for that the YCo5 target for sputtering was replaced by a CeCo5 target. 0441 The medium having the CeCo5 of 50 nm will be referred to as BB2 of the present invention. 0442 It should be noted we also prepared a medium having the CeCo5 film and the Co78Cr19Ta3 film in the reversed order. That is, firstly, CeCo5 film was formed on the FeSiAl film, and then the Co78Cr19Ta3 film was formed on the CeCo5 film. 0443 As has been shown in Example 12, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 film is 9.0105 erg/cc, whereas the perpendicular magnetic anisotropic energy of the CeCo5 film is 6.0107 erg/cc, which is by far greater than the Ku of the Co78Cr19Ta3 film. (See FIG. 90 and FIG. 7) 0444 By using a mono-pole/MR (magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium BB2 of the present invention and the conventional medium B1. The check conditions were the same as in Example 26. 0445 FIG. 124 shows the medium noise dependency on the recording density for the BB2 of the present invention and the conventional medium B1. As is clear from FIG. 124, the conventional medium B1 shows a very high medium noise in the lower recording density, whereas in the medium BB2 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium B1. This is because the medium BB2 of the present invention includes the film having much higher perpendicular magnetic anisotropy Ku than the Co78Cr19Ta3 and the film is formed on that Co78Cr19Ta3 film. Accordingly, in contrast to the conventional B1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0446 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 125. As is clear from FIG. 125, no output lowering can be seen up to 50 nm of the CeCo5 film. When the CeCo5 film thickness exceeds 50 nm, the medium noise cannot be improved (reduced). This is because if CeCo5 film thickness becomes too large, YCo5 film orientation in the perpendicular direction to the film surface is deteriorated and the perpendicular magnetic anisotropic energy Ku becomes smaller. Thus, it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the perpendicular magnetization film. 0447 As has been described above, the recording medium BB2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the BB2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. 0448 Moreover, when the CeCo5 film was provided under or both under and over the perpendicular magnetization film, similar results were obtained because of the aforementioned reasons. 0449 Furthermore, in the experiment using the ID/MR composite head used in Example 1 instead of the mono-pole composite head, similar results were obtained because of the aforementioned reasons.
EXAMPLE 28 0450 Media of Example 28 were prepared in the same way as Example 26, except for that the YCo5 target for sputtering was replaced by a SmCo5 target. 0451 The medium having the SmCo5 of 50 nm will be referred to as CC2 of the present invention. 0452 It should be noted we also prepared a medium having the SmCo5 film and the Co78Cr19Ta3 (at %) film in the reversed order. That is, firstly, SmCo5 film was formed on the FeSiAl film, and then the Co78Cr19Ta3 film was formed on the SmCo5 film. 0453 As has been shown in Example 13, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 film is 9.0105 erg/cc, whereas the perpendicular magnetic anisotropic energy of the SmCo5 film is 1.0108 erg/cc, which is by far greater than the Ku of the Co78Cr19Ta3 film. (See FIG. 90 and FIG. 7) 0454 By using a mono-pole/MR (magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium CC2 of the present invention and the conventional medium B1. The check conditions were the same as in Example 26. 0455 FIG. 126 shows the medium noise dependency on the recording density for the CC2 of the present invention and the conventional medium B1. As is clear from FIG. 126, the conventional medium B1 shows a very high medium noise in the lower recording density, whereas in the medium CC2 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium B1. This is because the medium CC2 of the present invention includes the film having much higher perpendicular magnetic anisotropy Ku than the Co78Cr19Ta3 and the film is formed on that Co78Cr19Ta3 film. Accordingly, in contrast to the conventional B1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0456 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 127. As is clear from FIG. 127, no output lowering can be seen up to 50 nm of the SmCo5 film. When the SmCo5 film thickness exceeds 50 nm, the medium noise cannot be improved (reduced). This is because if SmCo5 film thickness becomes too large, YCo5 film orientation in the perpendicular direction to the film surface is deteriorated and the perpendicular magnetic anisotropic energy Ku becomes smaller. Thus, it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the perpendicular magnetization film. 0457 As has been described above, the recording medium CC2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the CC2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. 0458 Moreover, when the SmCo5 film was provided under or both under and over the perpendicular magnetization film, similar results were obtained because of the aforementioned reasons. 0459 Furthermore, in the experiment using the ID/MR composite head used in Example 1 instead of the mono-pole composite head, similar results were obtained because of the aforementioned reasons.
EXAMPLE 29 0460 Media of Example 29 were prepared in the same way as Example 26, except for that the YCo5 target for sputtering was replaced by a LaCo5 target. 0461 The medium having the LaCo5 of 50 nm will be referred to as DD2 of the present invention. 0462 It should be noted we also prepared a medium having the LaCo5 film and the Co78Cr19Ta3 (at %) film in the reversed order. That is, firstly, LaCo5 film was formed on the FeSiAl film, and then the Co78Cr19Ta3 film was formed on the LaCo5 film. 0463 As has been shown in Example 14, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 film is 9.0105 erg/cc, whereas the perpendicular magnetic anisotropic energy of the LaCo5 film is 6.0107 erg/cc, which is by far greater than the Ku of the Co78Cr19Ta3 film. (See FIG. 90 and FIG. 7) 0464 By using a mono-pole/MR (magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium DD2 of the present invention and the conventional medium B1. The check conditions were the same as in Example 26. 0465 FIG. 128 shows the medium noise dependency on the recording density for the DD2 of the present invention and the conventional medium B1. As is clear from FIG. 128, the conventional medium B1 shows a very high medium noise in the lower recording density, whereas in the medium DD2 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium B1. This is because the medium DD2 of the present invention includes the film having much higher perpendicular magnetic anisotropy Ku than the Co78Cr19Ta3 and the film is formed on that Co78Cr19Ta3 film. Accordingly, in contrast to the conventional B1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0466 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 129. As is clear from FIG. 129, no output lowering can be seen up to 50 nm of the LaCo5 film. When the LaCo5 film thickness exceeds 50 nm, the medium noise cannot be improved (reduced). This is because if LaCo5 film thickness becomes too large, LaCo5 film orientation in the perpendicular direction to the film surface is deteriorated and the perpendicular magnetic anisotropic energy Ku becomes smaller. Thus, it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the perpendicular magnetization film. 0467 As has been described above, the recording medium DD2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the DD2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. 0468 Moreover, when the LaCo5 film was provided under or both under and over the perpendicular magnetization film, similar results were obtained because of the aforementioned reasons. 0469 Furthermore, in the experiment using the ID/MR composite head used in Example 11 instead of the mono-pole composite head, similar results were obtained because of the aforementioned reasons.
EXAMPLE 30 0470 Media of Example 30 were prepared in the same way as Example 26, except for that the YCo5 target for sputtering was replaced by a PrCo5 target. 0471 The medium having the PrCo5 of 50 nm will be referred to as EE2 of the present invention. 0472 It should be noted we also prepared a medium having the PrCo5 film and the Co78Cr19Ta3 (at %) film in the reversed order. That is, firstly, PrCo5 film was formed on the FeSiAl film, and then the Co78Cr19Ta3 film was formed on the PrCo5 film. 0473 As has been shown in Example 15, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 film is 9.0105 erg/cc, whereas the perpendicular magnetic anisotropic energy of the PrCo5 film is 8.0107 erg/cc, which is by far greater than the Ku of the Co78Cr19Ta3 film. (See FIG. 90 and FIG. 7) 0474 By using a mono-pole/MR (magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium EE2 of the present invention and the conventional medium B1. The check conditions were the same as in Example 26. 0475 FIG. 130 shows the medium noise dependency on the recording density for the EE2 of the present invention and the conventional medium B1. As is clear from FIG. 130, the conventional medium B1 shows a very high medium noise in the lower recording density, whereas in the medium EE2 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium B1. This is because the medium EE2 of the present invention includes the film having much higher perpendicular magnetic anisotropy Ku than the Co78Cr19Ta3 and the film is formed on the Co78Cr19Ta3 film. Accordingly, in contrast to the conventional B1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0476 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 131. As is clear from FIG. 131, no output lowering can be seen up to 50 nm of the PrCo5 film. When the PrCo5 film thickness exceeds 50 nm, the medium noise cannot be improved (reduced). This is because if PrCo5 film thickness becomes too large, PrCo5 film orientation in the perpendicular direction to the film surface is deteriorated and the perpendicular magnetic anisotropic energy Ku becomes smaller. Thus, it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the perpendicular magnetization film. 0477 As has been described above, the recording medium EE2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the EE2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. 0478 Moreover, when the PrCo5 film was provided under or both under and over the perpendicular magnetization film, similar results were obtained because of the aforementioned reasons. 0479 Furthermore, in the experiment using the ID/MR composite head used in Example 11 instead of the mono-pole composite head, similar results were obtained because of the aforementioned reasons.
EXAMPLE 31 0480 Media of Example 30 were prepared in the same way as Example 26, except for that the YCo5 target for sputtering was replaced by a Y2Co17 target. 0481 The medium having the Y2Co17 of 50 nm will be referred to as FF2 of the present invention. 0482 It should be noted we also prepared a medium having the Y2Co17 film and the Co78Cr19Ta3 (at %) film in the reversed order. That is, firstly, Y2Co17 film was formed on the FeSiAl film, and then the Co78Cr19Ta3 film was formed on the Y2Co17 film. 0483 As has been shown in Example 16, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 film is 9.0105 erg/cc, whereas the perpendicular magnetic anisotropic energy of the Y2Co17 film is 2.0107 erg/cc, which is by far greater than the Ku of the Co78Cr19Ta3 film. (See FIG. 90 and FIG. 7) 0484 By using a mono-pole/MR (magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium FF2 of the present invention and the conventional medium B1. The check conditions were the same as in Example 26. 0485 FIG. 132 shows the medium noise dependency on the recording density for the FF2 of the present invention and the conventional medium B1. As is clear from FIG. 132, the conventional medium B1 shows a very high medium noise in the lower recording density, whereas in the medium FF2 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium B1. This is because the medium FF2 of the present invention includes the film having much higher perpendicular magnetic anisotropy Ku than the Co78Cr19Ta3 and the film is formed on the Co78Cr19Ta3 film. Accordingly, in contrast to the conventional B1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0486 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 133. As is clear from FIG. 133, no output lowering can be seen up to 50 nm of the Y2Co17 film. When the Y2Co17 film thickness exceeds 50 nm, the medium noise cannot be improved (reduced). This is because if Y2Co17 film thickness becomes too large, Y2Co17 film orientation in the perpendicular direction to the film surface is deteriorated and the perpendicular magnetic anisotropic energy Ku becomes smaller. Thus, it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the perpendicular magnetization film. 0487 As has been described above, the recording medium FF2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the FF2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. 0488 Moreover, when the Y2Co17 film was provided under or both under and over the perpendicular magnetization film, similar results were obtained because of the aforementioned reasons. 0489 Furthermore, in the experiment using the ID/MR composite head used in Example 11 instead of the mono-pole composite head, similar results were obtained because of the aforementioned reasons.
EXAMPLE 32 0490 Media of Example 32 were prepared in the same way as Example 26, except for that the YCo5 target for sputtering was replaced by a Ce2Co17 target. 0491 The medium having the Ce2Co17 of 50 nm will be referred to as GG2 of the present invention. 0492 It should be noted we also prepared a medium having the Ce2Co17 film and the Co78Cr19Ta3 (at %) film in the reversed order. That is, firstly, Ce2Co17 film was formed on the FeSiAl film, and then the Co78Cr19Ta3 film was formed on the Ce2Co17 film. 0493 As has been shown in Example 17, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 film is 9.0105 erg/cc, whereas the perpendicular magnetic anisotropic energy of the Ce2Co17 film is 3.0107 erg/cc, which is by far greater than the Ku of the Co78Cr19Ta3 film. (See FIG. 90 and FIG. 7) 0494 By using a mono-pole/MR (magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium GG2 of the present invention and the conventional medium B1. The check conditions were the same as in Example 26. 0495 FIG. 134 shows the medium noise dependency on the recording density for the GG2 of the present invention and the conventional medium B1. As is clear from FIG. 134, the conventional medium B1 shows a very high medium noise in the lower recording density, whereas in the medium GG2 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium B1. This is because the medium GG2 of the present invention includes the film having much higher perpendicular magnetic anisotropy Ku than the Co78Cr19Ta3 and the film is formed on the Co78Cr19Ta3 film. Accordingly, in contrast to the conventional B1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0496 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 135. As is clear from FIG. 135, no output lowering can be seen up to 50 nm of the Ce2Co17 film. When the Ce2Co17 film thickness exceeds 50 nm, the medium noise cannot be improved (reduced). This is because if Ce2Co17 film thickness becomes too large, Ce2Co17 film orientation in the perpendicular direction to the film surface is deteriorated and the perpendicular magnetic anisotropic energy Ku becomes smaller. Thus, it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the perpendicular magnetization film. 0497 As has been described above, the recording medium GG2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the GG2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. 0498 Moreover, when the Ce2Co17 film was provided under or both under and over the perpendicular magnetization film, similar results were obtained because of the aforementioned reasons. 0499 Furthermore, in the experiment using the ID/MR composite head used in Example 11 instead of the mono-pole composite head, similar results were obtained because of the aforementioned reasons.
EXAMPLE 33 0500 Media of Example 33 were prepared in the same way as Example 26, except for that the YCo5 target for sputtering was replaced by a Sm2Co17 target. 0501 The medium having the Sm2Co17 of 50 nm will be referred to as HH2 of the present invention. 0502 It should be noted we also prepared a medium having the SmCo17 film and the Co78Cr19Ta3 (at %) film in the reversed order. That is, firstly, Sm2Co17 film was formed on the FeSiAl film, and then the Co78Cr19Ta3 film was formed on the Sm2Co17 film. 0503 As has been shown in Example 18, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 film is 9.0105 erg/cc, whereas the perpendicular magnetic anisotropic energy of the Sm2Co17 film is 4.2107 erg/cc, which is by far greater than the Ku of the Co78Cr19Ta3 film. (See FIG. 90 and FIG. 7) 0504 By using a mono-pole/MR (magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium HH2 of the present invention and the conventional medium B1. The check conditions were the same as in Example 26. 0505 FIG. 136 shows the medium noise dependency on the recording density for the HH2 of the present invention and the conventional medium B1. As is clear from FIG. 136, the conventional medium B1 shows a very high medium noise in the lower recording density, whereas in the medium HH2 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium B1. This is because the medium HH2 of the present invention includes the film having much higher perpendicular magnetic anisotropy Ku than the Co78Cr19Ta3 and the film is formed on the Co78Cr19Ta3 film. Accordingly, in contrast to the conventional B1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0506 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 137. As is clear from FIG. 137, no output lowering can be seen up to 50 nm of the Ce2Co17 film. When the Ce2Co17 film thickness exceeds 50 nm, the medium noise cannot be improved (reduced). This, is because if Sm2Co17 film thickness becomes too large, Sm2Co17 film orientation in the perpendicular direction to the film surface is deteriorated and the perpendicular magnetic anisotropic energy Ku becomes smaller. Thus, it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the perpendicular magnetization film. 0507 As has been described above, the recording medium HH2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the HH2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. 0508 Moreover, when the Sm2Co17 film was provided under or both under and over the perpendicular magnetization film, similar results were obtained because of the aforementioned reasons. 0509 Furthermore, in the experiment using the ID/MR composite head used in Example 11 instead of the mono-pole composite head, similar results were obtained because of the aforementioned reasons.
EXAMPLE 34 0510 Media of Example 34 were prepared in the same way as Example 26, except for that the YCo5 target for sputtering was replaced by a La2Co17 target. 0511 The medium having the La2Co17 of 50 nm will be referred to as JJ2 of the present invention. 0512 It should be noted we also prepared a medium having the La2Co17 film and the Co78Cr19Ta3 (at %) film in the reversed order. That is, firstly, La2Co17 film was formed on the FeSiAl film, and then the Co78Cr19Ta3 film was formed on the La2Co17 film. 0513 As has been shown in Example 19, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 film is 9.0105 erg/cc, whereas the perpendicular magnetic anisotropic energy of the La2Co17 film is 3.5107 erg/cc, which is by far greater than the Ku of the Co78Cr19Ta3 film. (See FIG. 90 and FIG. 7) 0514 By using a mono-pole/MR (magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium JJ2 of the present invention and the conventional medium B1. The check conditions were the same as in Example 26. 0515 FIG. 138 shows the medium noise dependency on the recording density for the JJ2 of the present invention and the conventional medium B1. As is clear from FIG. 138, the conventional medium B1 shows a very high medium noise in the lower recording density, whereas in the medium JJ2 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium B1. This is because the medium JJ2 of the present invention includes the film having much higher perpendicular magnetic anisotropy Ku than the Co78Cr19Ta3 and the film is formed on the Co78Cr19Ta3 film. Accordingly, in contrast to the conventional B1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0516 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 139. As is clear from FIG. 139, no output lowering can be seen up to 50 nm of the La2Co17 film. When the La2Co17 film thickness exceeds 50 nm, the medium noise cannot be improved (reduced). This is because if La2Co17 film thickness becomes too large, La2Co17 film orientation in the perpendicular direction to the film surface is deteriorated and the perpendicular magnetic anisotropic energy Ku becomes smaller. Thus, it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the perpendicular magnetization film. 0517 As has been described above, the recording medium JJ2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the JJ2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. 0518 Moreover, when the La2Co17 film was provided under or both under and over the perpendicular magnetization film, similar results were obtained because of the aforementioned reasons. 0519 Furthermore, in the experiment using the ID/MR composite head used in Example 11 instead of the mono-pole composite head, similar results were obtained because of the aforementioned reasons.
EXAMPLE 35 0520 Media of Example 35 were prepared in the same way as Example 26, except for that the YCo5 target for sputtering was replaced by a Pr2Co17 target. 0521 The medium having the Pr2Co17 of 50 nm will be referred to as KK2 of the present invention. 0522 It should be noted we also prepared a medium having the Pr2Co17 film and the Co78Cr19Ta3 (at %) film in the reversed order. That is, firstly, Pr2Co17 film was formed on the FeSiAl film, and then the Co78Cr19Ta3 film was formed on the Pr2Co17 film. 0523 As has been shown in Example 20, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 film is 9.0105 erg/cc, whereas the perpendicular magnetic anisotropic energy of the La2Co17 film is 2.7107 erg/cc, which is by far greater than the Ku of the Co78Cr19Ta3 film. (See FIG. 90 and FIG. 7) 0524 By using a mono-pole/MR (magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium KK2 of the present invention and the conventional medium B1. The check conditions were the same as in Example 26. 0525 FIG. 140 shows the medium noise dependency on the recording density for the KK2 of the present invention and the conventional medium B1. As is clear from FIG. 140, the conventional medium B1 shows a very high medium noise in the lower recording density, whereas in the medium KK2 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium B1. This is because the medium KK2 of the present invention includes the film having much higher perpendicular magnetic anisotropy Ku than the Co78Cr19Ta3 and the film is formed on the Co78Cr19Ta3 film. Accordingly, in contrast to the conventional B1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0526 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 141. As is clear from FIG. 141, no output lowering can be seen up to 50 nm of the Pr2Co17 film. When the Pr2Co17 film thickness exceeds 50 nm, the medium noise cannot be improved (reduced). This is because if Pr2Co17 film thickness becomes too large, Pr2Co17 film orientation in the perpendicular direction to the film surface is deteriorated and the perpendicular magnetic anisotropic energy Ku becomes smaller. Thus, it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the perpendicular magnetization film. 0527 As has been described above, the recording medium KK2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the KK2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. 0528 Moreover, when the Pr2Co17 film was provided under or both under and over the perpendicular magnetization film, similar results were obtained because of the aforementioned reasons. 0529 Furthermore, in the experiment using the ID/MR composite head used in Example 11 instead of the mono-pole composite head, similar results were obtained because of the aforementioned reasons.
EXAMPLE 36 0530 Media of Example 36 were prepared in the same way as Example 26, except for that the YCo5 target for sputtering was replaced by one of Ba ferrite materials, i.e., a BaFe12O19 target made from BaFe12O19. 0531 The medium having the BaFe12O19 of 50 nm will be referred to as LL2 of the present invention. 0532 It should be noted we also prepared a medium having the BaFe12O19 film and the Co78Cr19Ta3 (at %) film in the reversed order. That is, firstly, BaFe12O19 film was formed on the FeSiAl film, and then the Co78Cr19Ta3 film was formed on the BaFe12O19 film. 0533 As has been shown in Example 21, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 film is 9.0105 erg/cc, whereas the perpendicular magnetic anisotropic energy of the BaFe12O19 film is 3.3106 erg/cc, which is by far greater than the Ku of the Co78Cr19Ta3 film. (See FIG. 111 and FIG. 7) 0534 By using a mono-pole/MR (magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium LL2 of the present invention and the conventional medium B1. The check conditions were the same as in Example 26. 0535 FIG. 142 shows the medium noise dependency on the recording density for the LL2 of the present invention and the conventional medium B1. As is clear from FIG. 142, the conventional medium B1 shows a very high medium noise in the lower recording density, whereas in the medium LL2 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium B1. This is because the medium LL2 of the present invention includes the film having much higher perpendicular magnetic anisotropy Ku than the Co78Cr19Ta3 and the film is formed on the Co78Cr19Ta3 film. Accordingly, in contrast to the conventional B1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0536 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 143. As is clear from FIG. 143, no output lowering can be seen up to 50 nm of the BaFe12O19 film. When the BaFe12O19 film thickness exceeds 50 nm, the medium noise cannot be improved (reduced). This is because if the BaFe12O19 film thickness becomes too large, the BaFe12O19 film orientation in the perpendicular direction to the film surface is deteriorated and the perpendicular magnetic anisotropic energy Ku becomes smaller. Thus, it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the perpendicular magnetization film. 0537 As has been described above, the recording medium LL2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the LL2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. 0538 Moreover, when the BaFe12O19 film was provided under or both under and over the perpendicular magnetization film, similar results were obtained because of the aforementioned reasons. 0539 Furthermore, in the experiment using the ID/MR composite head used in Example 11 instead of the mono-pole composite head, similar results were obtained because of the aforementioned reasons.
EXAMPLE 37 0540 Media of Example 37 were prepared in the same way as Example 26, except for that the YCo5 target for sputtering was replaced by one of Ba ferrite materials, i.e., a BaFe18O27 target made from BaFe18O27. 0541 The medium having the BaFe18O27 of 50 nm will be referred to as MM2 of the present invention. 0542 It should be noted we also prepared a medium having the BaFe18O27 film and the Co78Cr19Ta3 (at %) film in the reversed order. That is, firstly, BaFe18O27 film was formed on the FeSiAl film, and then the Co78Cr19Ta3 film was formed on the BaFe18O27 film. 0543 As has been shown in Example 22, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 film is 9.0105 erg/cc, whereas the perpendicular magnetic anisotropic energy of the BaFe18O27 film is 3.0106 erg/cc, which is by far greater than the Ku of the Co78Cr19Ta3 film. (See FIG. 111 and FIG. 7) 0544 By using a mono-pole/MR (magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium MM2 of the present invention and the conventional medium B1. The check conditions were the same as in Example 26. 0545 FIG. 144 shows the medium noise dependency on the recording density for the MM2 of the present invention and the conventional medium B1. As is clear from FIG. 144, the conventional medium B1 shows a very high medium noise in the lower recording density, whereas in the medium MM2 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium B1. This is because the medium MM2 of the present invention includes the film having much higher perpendicular magnetic anisotropy Ku than the Co78Cr19Ta3 and the film is formed on the Co78Cr19Ta3 film. Accordingly, in contrast to the conventional B1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0546 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 145. As is clear from FIG. 145, no output lowering can be seen up to 50 nm of the BaFe18O27 film. When the BaFe18O27 film thickness exceeds 50 nm, the medium noise cannot be improved (reduced). This is because if the BaFe18O27 film thickness becomes too large, the BaFe18O27 film orientation in the perpendicular direction to the film surface is deteriorated and the perpendicular magnetic anisotropic energy Ku becomes smaller. Thus, it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the perpendicular magnetization film. 0547 As has been described above, the recording medium MM2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the MM2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. 0548 Moreover, when the BaFe18O27 film was provided under or both under and over the perpendicular magnetization film, similar results were obtained because of the aforementioned reasons. 0549 Furthermore, in the experiment using the ID/MR composite head used in Example 11 instead of the mono-pole composite head, similar results were obtained because of the aforementioned reasons.
EXAMPLE 38 0550 Media of Example 38 were prepared in the same way as Example 26, except for that the YCo5 target for sputtering was replaced by one of Sr ferrite materials, i.e., a SrFe12O19 target made from SrFe12O19. 0551 The medium having the SrFe12O19 of 50 nm will be referred to as NN2 of the present invention. 0552 It should be noted we also prepared a medium having the SrFe12O19 film and the Co78Cr19Ta3 (at %) film in the reversed order. That is, firstly, the SrFe12O19 film was formed on the FeSiAl film, and then the Co78Cr19Ta3 film was formed on the SrFe12O19 film. 0553 As has been shown in Example 23, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 film is 7.0105 erg/cc, whereas the perpendicular magnetic anisotropic energy of the SrFe12O19 film is 3.4106 erg/cc, which is by far greater than the Ku of the Co78Cr19Ta3 film. (See FIG. 111 and FIG. 7) 0554 By using a mono-pole/MR (magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium NN2 of the present invention and the conventional medium B1. The check conditions were the same as in Example 26. 0555 FIG. 146 shows the medium noise dependency on the recording density for the NN2 of the present invention and the conventional medium B1. As is clear from FIG. 146, the conventional medium B1 shows a very high medium noise in the lower recording density, whereas in the medium NN2 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium B1. This is because the medium NN2 of the present invention includes the film having much higher perpendicular magnetic anisotropy Ku than the Co78Cr19Ta3 and the film is formed on the Co78Cr19Ta3 film. Accordingly, in contrast to the conventional B1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0556 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 147. As is clear from FIG. 147, no output lowering can be seen up to 50 nm of the SrFe12O19 film. When the SrFe12O19 film thickness exceeds 50 nm, the medium noise cannot be improved (reduced). This is because if the SrFe12O19 film thickness becomes too large, the SrFe12O19 film orientation in the perpendicular direction to the film surface is deteriorated and the perpendicular magnetic anisotropic energy Ku becomes smaller. Thus, it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the perpendicular magnetization film. 0557 As has been described above, the recording medium NN2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the NN2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. 0558 Moreover, when the SrFe12O19 film was provided under or both under and over the perpendicular magnetization film, similar results were obtained because of the aforementioned reasons. 0559 Furthermore, in the experiment using the ID/MR composite head used in Example 11 instead of the mono-pole composite head, similar results were obtained because of the aforementioned reasons.
EXAMPLE 39 0560 Media of Example 39 were prepared in the same way as Example 26, except for that the YCo5 target for sputtering was replaced by one of Sr ferrite materials, i.e., a SrFe18O27 target made from SrFe18O27. 0561 The medium having the SrFe18027 of 50 nm will be referred to as PP2 of the present invention. 0562 It should be noted we also prepared a medium having the SrFe18O27 film and the Co78Cr19Ta3 (at %) film in the reversed order. That is, firstly, the SrFe18O27 film was formed on the FeSiAl film, and then the Co78Cr19Ta3 film was formed on the SrFe18O27 film. 0563 As has been shown in Example 24, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 film is 9.0105 erg/cc, whereas the perpendicular magnetic anisotropic energy of the SrFe18O27 film is 3.1106 erg/cc, which is by far greater than the Ku of the Co78Cr19Ta3 film. (See FIG. 111 and FIG. 7) 0564 By using a mono-pole/MR (magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium PP2 of the present invention and the conventional medium B1. The check conditions were the same as in Example 26. 0565 FIG. 148 shows the medium noise dependency on the recording density for the PP2 of the present invention and the conventional medium B1. As is clear from FIG. 148, the conventional medium B1 shows a very high medium noise in the lower recording density, whereas in the medium PP2 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium B1. This is because the medium PP2 of the present invention includes the film having much higher perpendicular magnetic anisotropy Ku than the Co78Cr19Ta3 and the film is formed on the Co80Cr19Ta3 film. Accordingly, in contrast to the conventional B1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0566 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 149. As is clear from FIG. 149, no output lowering can be seen up to 50 nm of the SrFe18O27 film. When the SrFe18O7 film thickness exceeds 50 nm, the medium noise cannot be improved (reduced). This is because if the SrFe18O27 film thickness becomes too large, the SrFe18O27 film orientation in the perpendicular direction to the film surface is deteriorated and the perpendicular magnetic anisotropic energy Ku becomes smaller. Thus, it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the perpendicular magnetization film. 0567 As has been described above, the recording medium PP2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the PP2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. 0568 Moreover, when the SrFe18O27 film was provided under or both under and over the perpendicular magnetization film, similar results were obtained because of the aforementioned reasons. 0569 Furthermore, in the experiment using the ID/MR composite head used in Example 11 instead of the mono-pole composite head, similar results were obtained because of the aforementioned reasons.
EXAMPLE 40 0570 Media of Example 40 were prepared in the same way as Example 26, except for that the YCo5 target for sputtering was replaced by Pt50Co50 (at %) target 0571 The medium having the Pt50Co50 of 50 nm will be referred to as QQ2 of the present invention. 0572 It should be noted we also prepared a medium having the Pt50Co50 film and the Co78Cr19Ta3 (at %) film in the reversed order. That is, firstly, the Pt50Co50 film was formed on the FeSiAl film, and then the Co78Cr19Ta3 film was formed on the Pt50Co50 film. 0573 As has been shown in Example 25, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3film is 9.0105 erg/cc, whereas the perpendicular magnetic anisotropic energy of the Pt50Co50 film is 1.0107 erg/cc, which is by far greater than the Ku of the Co78Cr19Ta3 film. (See FIG. 111 and FIG. 7) 0574 By using a mono-pole/MR (magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium QQ2 of the present invention and the conventional medium B1. The check conditions were the same as in Example 26. 0575 FIG. 150 shows the medium noise dependency on the recording density for the QQ2 of the present invention and the conventional medium B1. As is clear from FIG. 150, the conventional medium B1 shows a very high medium noise in the lower recording density, whereas in the medium QQ2 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium B1. This is because the medium QQ2 of the present invention includes the film having much higher perpendicular magnetic anisotropy Ku than the Co78Cr19Ta3 and the film is formed on the Co78Cr19Ta3 film. Accordingly, in contrast to the conventional B1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0576 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 151. As is clear from FIG. 151, no output lowering can be seen up to 50 nm of the Pt50Co50 (at %) film. When the Pt50Co50 film thickness exceeds 50 nm, the medium noise cannot be improved (reduced). This is because if the Pt50Co50 film thickness becomes too large, the Pt50Co50 film orientation in the perpendicular direction to the film surface is deteriorated and the perpendicular magnetic anisotropic energy Ku becomes smaller. Thus, it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the perpendicular magnetization film. 0577 As has been described above, the recording medium QQ2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the QQ2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. 0578 Moreover, when the Pt50Co50 (at %) film was provided under or both under and over the perpendicular magnetization film, similar results were obtained because of the aforementioned reasons. 0579 Furthermore, in the experiment using the ID/MR composite head used in Example 1 instead of the mono-pole composite head, similar results were obtained because of the aforementioned reasons.
EXAMPLE 41 0580 Media of Example 41 were prepared in the same way as Example 26, except for that for sputtering, the YCo5 target was replaced by SmCo5 target, and the FeSiAl target was replaced by a FeTaN target. 0581 The medium having the SmCo5 of 50 nm will be referred to as RR2 of the present invention. 0582 Note that we also prepared a medium having no SmCo5 film. This medium will be referred to as C1. 0583 We also prepared a medium having the SmCo5 film and the Co78Cr19Ta3 (at %) film in the reversed order. That is, firstly, the SmCo5 film was formed on the FeTaN film, and then the Co78Cr19Ta3 film was formed on the SmCo5 film. 0584 As has been shown in Example 13, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 film is 9.0105 erg/cc, whereas the perpendicular magnetic anisotropic energy of the SmCo5 film is 1.0108 erg/cc, which is by far greater than the Ku of the Co78Cr19Ta3 film. (See FIG. 90 and FIG. 7) 0585 By using a mono-pole/MR (magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium RR2 of the present invention and the conventional medium C1. The check conditions were the same as in Example 26. 0586 FIG. 152 shows the medium noise dependency on the recording density for the RR2 of the present invention and the conventional medium C1. As is clear from FIG. 152, the conventional medium C1 shows a very high medium noise in the lower recording density, whereas in the medium RR2 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium C1. This is because the medium RR2 of the present invention includes the film having much higher perpendicular magnetic anisotropy Ku than the Co78Cr19Ta3 and the film is formed on the Co78Cr19Ta3 film. Accordingly, in contrast to the conventional C1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0587 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 153. As is clear from FIG. 153, no output lowering can be seen up to 50 nm of the SmCo5 (at %) film. When the SmCo5 film thickness exceeds 50 nm, the medium noise cannot be improved (reduced). this is because if the SmCo5 film thickness becomes too large, the SmCo5 film orientation in the perpendicular direction to the film surface is deteriorated and the perpendicular magnetic anisotropic energy Ku becomes smaller. Thus, it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the perpendicular magnetization film. 0588 As has been described above, the recording medium RR2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the RR2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. 0589 Moreover, when the SmCo5 film was provided under or both under and over the perpendicular magnetization film, similar results were obtained because of the aforementioned reasons. 0590 Furthermore, in the experiment using the ID/MR composite head used in Example 11 instead of the mono-pole composite head, similar results were obtained because of the aforementioned reasons.
EXAMPLE 42 0591 Media of Example 42 were prepared in the same way as Example 41, except for that for sputtering, the SmCo5 target was replaced by Sm2Co17 target. 0592 The medium having the Sm2Co17 of 50 nm will be referred to as SS2 of the present invention. 0593 Note that we also prepared a medium having the Sm2Co17 film and the Co78Cr19Ta3 (at %) film in the reversed order. That is, firstly, the Sm2Co17 film was formed on the FeTaN film, and then the Co78Cr19Ta3 film was formed on the Sm2Co17 film. 0594 As has been shown in Example 18, the perpendicular magnetic anisotropic energy Ku of the Co78Cr19Ta3 film is 9.0105 erg/cc, whereas the perpendicular magnetic anisotropic energy of the Sm2co17 film is 4.2107 erg/cc, which is by far greater than the Ku of the Co78Cr19Ta3 film. (See FIG. 90 and FIG. 7) 0595 By using a mono-pole/MR (magneto-resistance effect) composite head, the recording/reproduction characteristics were checked on the medium SS2 of the present invention and the conventional medium C1. The check conditions were the same as in Example 26. 0596 FIG. 154 shows the medium noise dependency on the recording density for the SS2 of the present invention and the conventional medium C1. As is clear from FIG. 154, the conventional medium C1 shows a very high medium noise in the lower recording density, whereas in the medium SS2 of the present invention, the medium noise in the same recording region is much suppressed in comparison to the conventional medium C1. This is because the medium SS2 of the present invention includes the film having much higher perpendicular magnetic anisotropy Ku than the Co78Cr19Ta3 and the film is formed on the Co78Cr19Ta3 film. Accordingly, in contrast to the conventional C1, it is possible to much more suppress generation of reversed magnetic domain in the vicinity of the surface of the perpendicular magnetization film. 0597 Next, the film thickness of the film formed on the perpendicular magnetization film was gradually changed from 5 to 55 nm to check the medium noise values at recording density 10 KFRPI for all the film types. The results of this check are shown in FIG. 155. As is clear from FIG. 155, no output lowering can be seen up to 50 nm of the Sm2Co17 (at %) film. When the Sm2Co17 film thickness exceeds 50 nm, the medium noise cannot be improved (reduced). This is because if the Sm2Co17 film thickness becomes too large, the Sm2Co17 film orientation in the perpendicular direction to the film surface is deteriorated and the perpendicular magnetic anisotropic energy Ku becomes smaller. Thus, it becomes impossible to suppress generation of a reversed magnetic domain in the vicinity of the perpendicular magnetization film. 0598 As has been described above, the recording medium SS2 of the present invention shows a preferable medium noise characteristic even in a low recording density region. That is, by using the SS2 of the present invention, it is possible to realize suppression of medium noise increase in the low recording region. 0599 Moreover, when the Sm2Co17 film was provided under or both under and over the perpendicular magnetization film, similar results were obtained because of the aforementioned reasons. 0600 Furthermore, in the experiment using the ID/MR composite head used in Example 11 instead of the mono-pole composite head, similar results were obtained because of the aforementioned reasons. 0601 In the perpendicular magnetic recording media according to the present invention, a perpendicular magnetic film is provided with a high perpendicular orientation film which has a higher perpendicular orientation than that perpendicular magnetic film and formed over or under the perpendicular magnetic film. This significantly suppress medium noise, i.e., generation of a reversed magnetic domain in the vicinity of the surface of the perpendicular magnetic film. This enables to obtain a perpendicular magnetic recording medium having a preferable medium noise characteristic. 0602 This medium noise characteristic is further improved if the following condition is satisfied when the high perpendicular orientation film is formed using a CoCr alloy. 0603 That is, the perpendicular magnetic anisotropic energy Ku erg/cc an the saturation magnetization Ms emu/cc is in the relationship: R2Ku/4Ms2. If the CoCr alloy satisfies R1.4 an excellent effect can be obtained. 0604 When the high perpendicular orientation film is made from RCo5 (RY, Ce, Sm, La, Pr) film, Ba ferrite film, Sr ferrite, and PtCo, it is possible an excellent effect if these films has a perpendicular magnetic anisotropic energy Ku greater than the perpendicular magnetic anisotropic energy of the perpendicular magnetization film. 0605 The invention may be embodied in other specific forms without departing from the spirit or essential characteristic thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. 0606 The entire disclosure of Japanese Patent Application No. 10-244060 (Filed on Aug. 28th, 1998) including specification, claims, drawings and summary are incorporated herein by reference in its entirety.
Patent Prosecution report image

Empower your practice with Patexia Publication Prosecution IP Module.

Get access to our exclusive rankings and unlock powerful data.
Check our Latest ReportPurchase IP Module

Looking for a Publication Attorney?

Get in touch with our team or create your account to start exploring a network of over 120K attorneys.