JP2001060312A - Magnetic recording media - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lessen the influence of thermal fluctuation and to permit a high recording density by consisting a magnetic recording layer of an amorphous alloy which has perpendicular magnetic anisotropy and is composed of a light rare earth metal, heavy rare earth metal and 3d transition metal. SOLUTION: The magnetic recording medium is constituted by successively laminating the magnetic recording layer 2 and an antioxidant layer 3 on a substrate 1. A glass substrate is used as the substrate 1 and is formed by successively depositing a PrTbCo alloy film which constitutes the magnetic recording layer 2 and a Ta film which constitutes the antioxidant layer 3 thereon in the same vacuum after discharge. A composite target arranged with pellets of Pr and Tb on a Co target is used for formation of the PrTbCo alloy film which constitutes the magnetic recording layer 2. A soft magnetic layer, such as an Fe film, Co film or Ni-Fe alloy film is deposited between the substrate 1 and the magnetic recording layer 2, by which the steep recording may be executed in a perpendicular direction even when a ring head is used. If a single magnetic pole head is used, the leakage of the magnetic fields in a track direction is lessened and the recording density may be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium having perpendicular magnetic anisotropy used for magnetic recording.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for higher density and higher storage capacity in magnetic recording devices such as magnetic disks. With such an increase in recording density, the size of recording bits has become smaller and closer to the dimensions of the crystal grains constituting the thin-film magnetic recording medium, and as a result, the crystal grains have such a size that they behave like a single magnetic domain. It is necessary to promote magnetic separation between them. Further, when the number of crystal grains included in one bit decreases, noise increases. Therefore, it is necessary to reduce the crystal grain size as the recording density increases. However,
When the crystal grains are too fine, instability of magnetization due to thermal fluctuations is caused.

[0003] The results of a computer simulation study of the thermal stability of recording magnetization based on a micromagnetics model have been reported ("Monte Carlo simulation of thermal fluctuations in perpendicular recording media and longitudinal recording media", Yasutarou Uesaka et al. IEICE Technical Report MR96-37 1
996-11).

According to this, in both the longitudinal magnetic recording and the perpendicular magnetic recording, the thermal stability index KuV /
It is said that when kT becomes 100 or less, the recording magnetization decreases. Where Ku is the magnetic anisotropic energy, V
Is the activation volume that is the unit of magnetization reversal, k is the Boltzmann constant, and T is the absolute temperature. Therefore, it is expected that a perpendicular magnetic recording medium, which can have a large medium thickness, is more advantageous for deterioration due to thermal fluctuation of recording magnetization.

[0005] Based on the above reported results, the results of studies on recording density characteristics, medium noise characteristics, and the like have been reported for perpendicular magnetic recording media of CoCrPt and CoCrPtTa alloy. Density Magnetic Recording ”Masaaki Nihon et al. Journal of the Japan Society of Applied Magnetics Vo
l. 21 No. 6 pp950-958 199
7) When the recording density is 30 to 40 Gb / in ² , KuV
The value of / kT increases to about 130 in perpendicular magnetic recording, while it increases to about 40 in longitudinal magnetic recording.

[0006]

However, further considerations are needed in view of the critical value of 100. In determining the value of KuV / kT, the value of Ku is determined by an experiment using a single crystal magnetic thin film, but the activation volume V is determined by the crystal grain size and the film thickness of the medium. Are used, and the reliability of the above values is considered to be insufficient. Further, in both the longitudinal magnetic recording medium and the perpendicular magnetic recording medium, as long as a crystalline material is used, if the crystal grain size is reduced to reduce the medium noise, the influence of thermal fluctuation increases. Problems are inherently difficult to avoid.

Accordingly, an object of the present invention is to provide a magnetic recording medium in which the influence of thermal fluctuation is small in such a situation and the recording density of a conventional magnetic recording medium can be exceeded. And

[0008]

In order to solve the above problems, attention has been paid to an amorphous perpendicular magnetic recording medium. Since the amorphous material has no crystal grains, the activation volume V is not controlled by the particle size. Therefore, it is possible to have a large activation volume V, and it is expected that the material is less likely to be affected by thermal fluctuation as compared with a crystalline material.

A magneto-optical recording medium is well known as an amorphous perpendicular magnetic recording medium. However, in the magneto-optical recording medium, an alloy of a heavy rare earth metal and a 3d transition metal is used, and the coercive force H is adjusted by adjusting the compensation temperature to around room temperature.
c diverges and keeps record. Therefore, at room temperature, the magnetic moments of the heavy rare earth metal and the 3d transition metal cancel each other out, and the saturation magnetization Ms is small, so that the magnetic recording medium cannot be used for recording and reproduction with a magnetic head. This is because a magnetic recording medium recorded and reproduced by a magnetic head must have a large saturation magnetization and a certain coercive force at room temperature.

On the other hand, in an alloy of a light rare earth metal and a 3d transition metal, a large saturation magnetization Ms is obtained because the magnetic moments are coupled in parallel. Japanese Patent Application Laid-Open No.
An Nd ₁₅ Co ₈₅ amorphous alloy film is reported in an example of Japanese Patent No. 54358. However, although it has been reported that the use of such an alloy thin film reduces the medium noise, it does not describe the effect of thermal fluctuation.
Although there is no clear description in the specification, it is presumed to be an in-plane magnetic recording medium from the cause of the medium noise and the alloy composition described above.

As an amorphous perpendicular magnetic recording medium made of an alloy of a light rare earth metal and a 3d transition metal, PrCo has been reported as an example (“MAGNETIZATION,
CURIE TEMPERATURE AND PER
PENDICULAR MAGNETIC ANISO
TROPY OF EVAPORATED Co-RA
RE EARTH AMORPHOUS ALLOY
FILMS "M. TAKAHASHI et al.
J. MAGNETIZM AND MAGNETIC
MATERIALS Vol. 75 pp252-26
2 1988). However, when a magnetic recording medium was actually prepared and the characteristics of PrCo described above were measured, the coercive force Hc was as small as about 200 Oe in the entire composition region that was amorphous and exhibited perpendicular magnetic anisotropy. It could not be used as a medium.

As a result of further study on such a situation, a method for increasing the coercive force Hc without lowering other characteristics was found.

That is, the present invention relates to a magnetic recording medium having at least a magnetic recording layer provided on a substrate, wherein the magnetic recording layer has perpendicular magnetic anisotropy, and comprises a light rare earth metal and a heavy rare earth. It is characterized by comprising an amorphous alloy composed of a metal and a 3d transition metal.

Further, according to the present invention, the magnetic recording layer may include Pr
It is characterized by being made of a TbCo alloy.

Furthermore, the present invention, the composition of the PrTbCo alloy _{(Pr (1-x) Tb} x) (1-y) Co y (0.4 ≦ x ≦ 0.8,0.77 ≦ y ≦ 0 .85).

Further, the present invention is characterized in that a soft magnetic layer is formed between the substrate and the magnetic recording layer.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

[Embodiment 1] In this embodiment, Pr is used as a light rare earth metal, Tb is used as a heavy rare earth metal,
Co was used as d transition metal.

FIG. 1 is a diagram showing the configuration of the magnetic recording medium of the present invention. As shown in FIG. 1, the magnetic recording medium is obtained by sequentially laminating a magnetic recording layer 2 and an antioxidant layer 3 on a substrate 1. As the substrate 1, a glass substrate (Corning: # 7)
059), and after evacuation to 0.4 μTorr or less, a PrTbCo alloy film to be the magnetic recording layer 2 and a Ta film to be the antioxidant layer 3 are sequentially formed in the same vacuum. At this time, for the formation of the PrTbCo alloy film to be the magnetic recording layer 2, a composite target in which Pr and Tb pellets are arranged on a Co target is used. Both the PrTbCo alloy film and the Ta film are formed by DC magnetron sputtering, and the Ar gas pressure is 5 mTorr, the PrTbCo alloy film is Power = 620 mW / cm ² , and the Ta film is Po.
The film was formed under a film forming condition of wer = 86 mW / cm ² . The film thickness was set at 500 ° and 100 °, respectively. The substrate 1 was formed by water cooling.

Since the PrTbCo alloy film obtained by the above method is amorphous, the activation volume V is evaluated from the crystal grain size as in the prior art in evaluating the index of thermal stability KuV / kT. Can not do it. Therefore, the thermal stability was evaluated using the fluctuation field Hf obtained from the dependency of the remanence retention force on the time of applying a magnetic field. For this, "C
Magnetic Viscosity and Noise Characteristics of oCrTa and CoCrPt Thin-Film Media ”Kazusuke Yamanaka et al.
1995-06. In the case of the fluctuation field Hf, contrary to the case of the thermal stability index KuV / kT,
It is considered that the lower the value, the better the thermal stability. According to this, there is an advantage that Hf can be directly determined from measurement of macro magnetic characteristics without requiring micro measurement such as crystal grain size.

First, the case where the composition of Co of the PrCo alloy is fixed at 83 atomic% and Pr is replaced by Tb will be described.

FIG. 2 shows a change in the fluctuation field Hf, FIG. 3 shows a change in the saturation magnetization Ms, and FIG. 4 shows a change in the coercive force Hc. FIG. 5 shows a change in perpendicular magnetic anisotropy energy K⊥ and a change in Ku (= K⊥ + 2πMs ² (demagnetizing field energy)). Here, the Tb composition ratio is represented by the composition ratio of Tb in the rare earth element.

In the variation of the fluctuation field Hf shown in FIG. 2, for comparison, a conventional crystalline medium, Co _0.76 Cr _0.16 Ta, was used for comparison.
As a result of performing the same measurement on the _0.03 Pt _0.05 film, Hf
= 19 Oe was obtained. As compared with FIG.
It can be seen that when the b composition ratio is 0.7 or less, the thermal stability is superior to that of the conventional crystalline medium.

3 and 4, when Pr is replaced by Tb, the saturation magnetization Ms decreases, but the coercive force H
c is increasing. Further, as shown in FIG. 5, each of the prepared media has a positive K⊥, and can be used as a perpendicular magnetic recording medium.

Based on the above measurement results, the value of KuV / kT is determined as in the case of the conventional crystalline medium. For example, with respect to the (Pr _0.53 Tb _0.47 ) _0.17 Co _0.83 film, the activation volume V (= kT / HfMs) is obtained from the measured values of the fluctuation field Hf (see FIG. 2) and the saturation magnetization Ms (see FIG. 3). When the value of KuV / kT is determined using the measured value of the anisotropic energy Ku (see FIG. 5), a very large value of 4000 or more is obtained. From this, it can be said that the thermal stability is very excellent.

In the magnetic recording medium, information is recorded by applying an external magnetic field with a magnetic head, and the information is reproduced by detecting the magnetic field generated from the residual magnetization with the magnetic head. Therefore, it is preferable that the magnetic recording medium has a saturation magnetization Ms of about 200 emu / cc or more and a coercive force Hc of 5 emu / cc.
3 and FIG. 4 satisfies this condition when the Tb composition ratio is in the range of about 0.4 to 0.8. Further, in terms of obtaining a high recording density, it is more preferable that the saturation magnetization Ms is about 300 emu / cc or more, the coercive force Hc is about 1000 Oe or more, and the Tb composition ratio is about 0.41 to 0.65. Satisfies this condition.

On the other hand, if Tb is too small, the coercive force Hc decreases, and a sufficiently small magnetization reversal region cannot be formed. If Tb is too large, the saturation magnetization Ms decreases.
In particular, when the recording density increases, a sufficient reproduction output cannot be obtained.

In the above range, as is apparent from FIG. 5, both Ku and K⊥ have sufficiently large values for a perpendicular magnetic recording medium. In particular, when the Tb composition ratio is in the range of about 0.4 to 0.6, 1 × 10 ⁷ er
It shows a very large perpendicular magnetic anisotropy of g / cc or more.

Further, (Pr _0.53 Tb _0.47 ) _0.17 Co
As a result of measuring the magnetization curve of the _0.83 alloy film, the squareness ratio, which is the ratio between the residual magnetization Mr and Ms, was almost 1. Therefore,
Even during high-density recording, the residual magnetization is large, and a large reproduction output can be obtained.

Next, the composition ratio in the rare earth element is expressed as Pr =
The case where the composition is changed to 0.4 and Tb = 0.6 and the rare earth element and Co are changed will be described.

FIG. 6 shows a change in the fluctuation field Hf, FIG. 7 shows a change in the saturation magnetization Ms, and FIG. 8 shows a change in the coercive force Hc. FIG. 9 shows a change in perpendicular magnetic anisotropy energy K⊥ and a change in Ku (= K⊥ + 2πMs2 (demagnetizing field energy)).

[0032] In variation of the fluctuation field Hf in FIG. _{6, Co 0.76 Cr 0. 16 Ta} 0.03 Pt 0.05 a conventional crystalline media
Compared with the fluctuation field Hf = 19 Oe of the film, it can be seen that the Co composition is 0.77 or more and the thermal stability is superior to the conventional crystalline medium.

As shown in FIGS. 7 and 8, when Co is increased with respect to the rare earth element, the saturation magnetization Ms monotonously increases, but the coercive force Hc once decreases and then decreases. Also,
As shown in FIG. 9, all of the created media have a positive K⊥ and can be used as a perpendicular magnetic recording medium.

In the magnetic recording medium, information is recorded by applying an external magnetic field with a magnetic head, and information is reproduced by detecting a magnetic field generated from the residual magnetization with the magnetic head. Therefore, it is preferable that the magnetic recording medium has a saturation magnetization Ms of about 200 emu / cc or more and a coercive force Hc of 5 emu / cc.
It is about 00 Oe or more, and from FIGS. 7 and 8, this condition is satisfied when the Co composition is in the range of 0.77 to 0.85. Further, from the viewpoint that a high recording density can be obtained, it is more preferable that the saturation magnetization Ms is about 300 emu / cc or more, the coercive force Hc is about 1000 Oe or more, and the Co composition is in the range of 0.79 to 0.83. Satisfies this condition.

When the Co composition is more than this,
When the coercive force Hc decreases and a sufficiently small magnetization reversal region cannot be formed, and the Co composition decreases from the above range, the saturation magnetization Ms decreases, and especially when the recording density increases, sufficient reproduction output is obtained. Can not be obtained.

In the above range, as is apparent from FIG. 9, both Ku and K⊥ have sufficiently large values for a perpendicular magnetic recording medium.

[Embodiment 2] In this embodiment, Ce is used as the light rare earth metal, and Tb is used as the heavy rare earth metal.
Co was used as d transition metal.

The magnetic recording layer of this embodiment, CeTbCo
The alloy film uses a composite target in which Tb and Ce pellets are arranged on a Co target, and has a composition of Ce.
_6.5 Tb _7.2 Co _86.3 was prepared. The composition of the magnetic recording layer of this embodiment is not limited to this composition.

In addition, since the configuration of the magnetic recording medium, layer forming conditions, and the like are the same as those in the first embodiment, the details are omitted here.

Next, Table 1 shows the saturation magnetization Ms, coercive force Hc, and perpendicular magnetic anisotropy energy K of the CeTbCo alloy film.
⊥, squareness ratio Mr / Ms, and fluctuation field Hf are shown. In the table, (Pr _0.53 T
b _0.47 ) Each characteristic of the _0.17 Co _0.83 alloy film is also shown.

[0041]

[Table 1] From Table 1, it can be seen that even when the light rare earth metal is changed from Pr to Ce, the condition that the saturation magnetization Ms is about 200 emu / cc or more and the coercive force Hc is about 500 Oe or more is satisfied, and the magnetic recording medium can be used. You can see that.

The value of the perpendicular magnetic anisotropy energy K⊥ is positive, and can be used as a perpendicular magnetic recording medium.

Further, the squareness ratio Mr / Ms, which is the ratio of the residual magnetization Mr to the saturation magnetization Ms, is almost 1. Even during high-density recording, the residual magnetization is large, and a large reproduction output can be obtained.

Further, the value of the fluctuation field Hf is 9.4 Oe, which is Co _0.76 Cr _0.16 Ta _0.03 Pt which is a conventional crystalline medium.
The Hf of the _0.05 film is very small compared to 19Oe, and it is understood that the thermal stability is superior to that of the conventional crystalline medium.

Embodiment 3 In this embodiment, Nd is used as a light rare earth metal, and Tb is used as a heavy rare earth metal.
Co was used as d transition metal.

The magnetic recording layer of this embodiment, NdTbCo
The alloy film uses a composite target in which pellets of Tb and Nd are arranged on a Co target and has a composition of Nd.
_7.2 Tb _7.8 Co _85.0 was prepared. The composition of the magnetic recording layer of this embodiment is not limited to this composition.

In addition, the configuration of the magnetic recording medium, layer forming conditions, and the like are the same as those in the first embodiment, and therefore, the details are omitted here.

Next, Table 2 shows the saturation magnetization Ms, coercive force Hc, and perpendicular magnetic anisotropy energy K of the NdTbCo alloy film.
⊥, squareness ratio Mr / Ms, and fluctuation field Hf are shown. In the table, (Pr _0.53 T
b _0.47 ) Each characteristic of the _0.17 Co _0.83 alloy film is also shown.

[0049]

[Table 2] From Table 2, it can be seen that even when the light rare earth metal is changed from Pr to Nd, the condition that the saturation magnetization Ms is about 200 emu / cc or more and the coercive force Hc is about 500 Oe or more is satisfied, and the magnetic recording medium can be used. You can see that.

The value of the perpendicular magnetic anisotropy energy K⊥ is positive, and can be used as a perpendicular magnetic recording medium.

The squareness ratio Mr / Ms, which is the ratio between the residual magnetization Mr and the saturation magnetization Ms, is almost 1. Even during high-density recording, the residual magnetization is large, and a large reproduction output can be obtained.

Further, the value of the fluctuation field Hf is 6.2 Oe, which is Co _0.76 Cr _0.16 Ta _0.03 Pt which is a conventional crystalline medium.
The Hf of the _0.05 film is very small compared to 19Oe, and it is understood that the thermal stability is superior to that of the conventional crystalline medium.

[Embodiment 4] In this embodiment, Sm is used as a light rare earth metal, and Tb is used as a heavy rare earth metal.
Co was used as d transition metal.

The magnetic recording layer of this embodiment, SmTbCo
The alloy film uses a composite target in which Tb and Sm pellets are arranged on a Co target, and the composition thereof is Sm.
_7.3 Tb _8.1 Co _84.6 was prepared. The composition of the magnetic recording layer of this embodiment is not limited to this composition.

In addition, since the configuration of the magnetic recording medium, layer forming conditions, and the like are the same as those in the first embodiment, the details are omitted here.

Next, Table 3 shows the saturation magnetization Ms, coercive force Hc, and perpendicular magnetic anisotropy energy K of the SmTbCo alloy film.
⊥, squareness ratio Mr / Ms and fluctuation field Hf are shown. In the table, (Pr _0.53 T
b _0.47 ) Each characteristic of the _0.17 Co _0.83 alloy film is also shown.

[0057]

[Table 3] From Table 3, it can be seen that even when the light rare earth metal is changed from Pr to Sm, the condition that the saturation magnetization Ms is about 200 emu / cc or more and the coercive force Hc is about 500 Oe or more is satisfied, and the magnetic recording medium can be used. You can see that.

The value of the perpendicular magnetic anisotropy energy K⊥ is positive, and can be used as a perpendicular magnetic recording medium.

The squareness ratio Mr / Ms, which is the ratio between the residual magnetization Mr and the saturation magnetization Ms, is almost 1. Even during high-density recording, the residual magnetization is large, and a large reproduction output can be obtained.

Further, the value of the fluctuation field Hf is also 10.4 Oe.
And the conventional crystalline medium of Co _0.76 Cr _0.16 Ta _0.03 P
very small compared to t _0.05 film of Hf = 19Oe, it is excellent in thermal stability than conventional crystalline media.

Embodiment 5 In this embodiment, Pr is used as a light rare earth metal, Dy is used as a heavy rare earth metal,
Co was used as d transition metal.

The magnetic recording layer of this embodiment, PrDyCo
The alloy film uses a composite target in which Dy and Pr pellets are arranged on a Co target, and the composition thereof is Pr.
_7.0 Dy _20.3 Co _72.7 was prepared. The composition of the magnetic recording layer of this embodiment is not limited to this composition.

Since the configuration of the magnetic recording medium, the layer forming conditions, and the like are the same as those in the first embodiment, the details are omitted here.

Next, Table 4 shows the saturation magnetization Ms, coercive force Hc and perpendicular magnetic anisotropy energy K of the PrDyCo alloy film.
⊥, squareness ratio Mr / Ms and fluctuation field Hf are shown. In the table, (Pr _0.53 T
b _0.47 ) Each characteristic of the _0.17 Co _0.83 alloy film is also shown.

[0065]

[Table 4] From Table 4, it can be seen that even when the heavy rare earth metal is changed from Tb to Dy, the condition that the saturation magnetization Ms is about 200 emu / cc or more and the coercive force Hc is about 500 Oe or more is satisfied, and the magnetic recording medium can be used. You can see that.

The value of the perpendicular magnetic anisotropy energy K⊥ is positive, and can be used as a perpendicular magnetic recording medium.

Further, the squareness ratio Mr / Ms, which is the ratio of the residual magnetization Mr to the saturation magnetization Ms, is almost 1. Even during high-density recording, the residual magnetization is large, and a large reproduction output can be obtained.

Further, the value of the fluctuation field Hf is also 11.0 Oe.
And the conventional crystalline medium of Co _0.76 Cr _0.16 Ta _0.03 P
very small compared to t _0.05 film of Hf = 19Oe, it is excellent in thermal stability than conventional crystalline media.

Further, as another example of the magnetic recording media of Examples 1 to 5, a soft magnetic layer is formed between the substrate and the magnetic recording layer. For the soft magnetic layer, an Fe film, a Co film, a Ni-
An Fe alloy film, a Co—Fe alloy film, an Fe—Al—Si alloy film, a Co—Zr—Nb alloy film, or the like is used.

By doing so, the magnetic recording layer is sandwiched between the magnetic head and the soft magnetic layer, and even when a ring head is used for recording, it is possible to perform steeper recording in the vertical direction. When a single pole head is used for recording, the soft magnetic layer plays the role of a second pole. When a single pole head is used, the leakage of the magnetic field in the track direction is smaller than when a ring head is used, so that the track pitch can be narrowed and the recording density can be further increased.

In the above description, Pr is used as the light rare earth metal,
Using Ce, Nd and Sm, Tb and D as heavy rare earth metals
Although description is made using Co as the 3d transition metal using y, the present invention is not limited to this, and heavy rare earth metals (Gd, Ho, Er) other than Tb and Dy, and 3d transition metals (F
e) may be used.

In the above description, a glass substrate is used as the substrate 1. However, other substrates such as aluminum alloys, ceramics, and plastics, or substrates subjected to a surface treatment on these substrates can also be used. Further, not only a rigid substrate such as a glass substrate but also a flexible substrate can be used.

In the above description, the antioxidant layer 3 is made of Ta.
Although a membrane was used, other inorganic materials such as carbon and alumina could be used. Further, it is also possible to form a lubricating layer thereon and use it. Furthermore, the substrate 1 and the magnetic recording layer 2
It is also possible to add an antioxidant layer or the like between them.

[0074]

As described above, according to the present invention, it is possible to provide a high recording density magnetic recording medium having a high saturation magnetization, a high coercive force, and a high perpendicular magnetic anisotropy with little influence of thermal fluctuation.

In particular, since the influence of the thermal fluctuation is small, the recorded magnetization is hardly attenuated over time, and the recording is stably stored for a long period of time. In addition, since it is amorphous, there are no crystal grains in the magnetization transition region and there is no fluctuation of magnetization due to exchange interaction between crystal grains, so that medium noise can be reduced.
Further, since the perpendicular magnetic anisotropy is very large, the width of the domain wall becomes small, which is advantageous for high-density recording. Further, since the squareness ratio is almost 1, the residual magnetization at the time of recording is large, and a large reproduction output can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a magnetic recording medium according to an embodiment of the present invention.

FIG. 2 is a diagram showing a change in Hf when the relative composition of Pr and Tb in a PrTbCo alloy film is changed.

FIG. 3 is a diagram showing a change in Ms when the relative composition of Pr and Tb of a PrTbCo alloy film is changed.

FIG. 4 is a diagram showing a change in Hc when the relative composition of Pr and Tb in a PrTbCo alloy film is changed.

FIG. 5 is a diagram showing changes in K⊥ and Ku when the relative composition of Pr and Tb in a PrTbCo alloy film is changed.

FIG. 6 is a diagram showing a change in Hf when the composition of a rare earth metal and Co in a PrTbCo alloy film is changed.

FIG. 7 is a diagram showing a change in Ms when the composition of a rare earth metal and Co in a PrTbCo alloy film is changed.

FIG. 8 is a diagram showing a change in Hc when the composition of a rare earth metal and Co in a PrTbCo alloy film is changed.

FIG. 9 is a diagram showing changes in K⊥ and Ku when the composition of the rare earth metal and Co in the PrTbCo alloy film is changed.

[Description of Signs] 1 substrate 2 magnetic recording layer 3 antioxidant layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hidekazu Hayashi 22-22, Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Tomohisa Koda 22-22, Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Incorporated (72) Inventor Souji Minami 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Toru Kira 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Sharp Corporation F term (reference) 5D006 BB01 BB07 CA03 DA08 EA03 FA04 FA09

Claims (4)

[Claims] 1. A magnetic recording medium provided with at least a magnetic recording layer on a substrate, wherein the magnetic recording layer has perpendicular magnetic anisotropy, and has a light rare earth metal, a heavy rare earth metal, and a 3d transition. A magnetic recording medium comprising an amorphous alloy composed of a metal. 2. The magnetic recording medium according to claim 1, wherein said magnetic recording layer is made of a PrTbCo alloy. The composition of claim 3 wherein said PrTbCo alloy and _{(Pr (1-x) Tb} x) (1-y) Co y (0.4 ≦ x ≦ 0.8,0.77 ≦ y ≦ 0.85) 3. The magnetic recording medium according to claim 2, wherein: 4. The magnetic recording medium according to claim 1, wherein a soft magnetic layer is formed between the substrate and the magnetic recording layer.