JP2001148109A - Magnetic disk, magnetic disk device - Google Patents

Abstract

(57) [Summary] (With correction) [Problem] To provide an information recording medium suitable for performing ultra-high density recording. The problem has been solved by using a magnetic film having two layers as a magnetic film for magnetic recording. The first magnetic film uses a ferrimagnetic amorphous alloy made of a rare earth-iron group. This magnetic film has a large magnetic anisotropy in a direction perpendicular to the substrate and has a large activation volume, so that it is suitable for high-density magnetic recording having high thermal stability. Further, the second magnetic film forms a perpendicular magnetization film having a larger saturation magnetization than the first magnetic film. This is effective in reducing the noise due to the magnetic recording medium and increasing the reproduction output.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium for storing a large amount of information quickly and accurately, and more particularly to a magnetic film for magnetic recording which has high performance and high reliability and uses the same. The present invention relates to a magnetic disk and a magnetic disk device.

[0002]

2. Description of the Related Art In recent years, there has been a remarkable progress in the advanced information society, and multimedia in which various forms of information are integrated has rapidly spread. One of the information recording devices that support this is a magnetic disk device. At present, the magnetic disk drive is being downsized while improving the recording density. At the same time, the cost of disk devices has been rapidly reduced. By the way, in order to realize a higher recording capacity of the magnetic disk, 1) shorten the distance between the disk and the magnetic head, 2) increase the coercive force of the medium, and 3) devise a signal processing method. 4) Developing a medium with small thermal fluctuation is an essential technology.

[0003] Above all, in a magnetic recording medium, an increase in coercive force is essential for realizing high-density magnetic recording. At present, a Co-Cr-Pt (-Ta) system is widely used as a magnetic recording medium. This material is a crystalline material in which about 20 nm of Co crystal particles are precipitated. Using this material, 40
In order to achieve a surface recording density exceeding Gb / in ² , precise control is performed by further reducing the unit (magnetic cluster) where magnetization reversal occurs during recording or erasing, and further reducing the particle size distribution. Must. As a result, noise generated from the medium during reproduction can be reduced. Furthermore, if there is a distribution in the crystal grain size,
In particular, when small-sized particles are present, thermal demagnetization occurs or thermal fluctuations occur, so that the formed magnetic domains may not exist stably. As described above, from the viewpoint of thermal demagnetization and thermal fluctuation reduction, controlling the crystal grain size distribution has become an important technique. As a method for achieving these, it has been proposed to provide a seed film below the magnetic film. USP-4652499 as an example
Can be given.

[0004]

In the above prior art,
First, in a magnetic disk, there is a limit in controlling the crystal grain size distribution of an information recording magnetic film by a seed layer, and fine particles and coarse particles may coexist. These fine particles and coarse particles are
When recording information (when reversing the magnetization), it is affected by the leakage magnetic field from the surrounding magnetic particles, and conversely, for large particles, it has an ultra-high density exceeding 40 Gb / inch ² to give an interaction. When performing recording, there is a problem that stable recording cannot be performed. In this regard, KuV / kT (Ku: magnetic anisotropy energy, V: activation volume, k: Boltzmann constant,
The value of the activation volume is an important parameter in the thermal stability expressed by (T: temperature). The larger the value, the more thermally stable. At the same time, Ku is also significantly involved in thermal stability. This tendency is the same in a Co—Cr-based magnetic film for perpendicular magnetic recording. This is an inevitable problem to be solved when using a crystalline magnetic material.

In view of such circumstances, a first object of the present invention is to provide a magnetic material for magnetic recording which has a large apparent activation volume and is excellent in thermal stability. Next, a second object of the present invention is to provide a low-noise magnetic recording magnetic material in which the shape of a magnetic domain in a magnetization transition region does not form a zigzag pattern, and a low-noise magnetic recording medium that does not reflect this pattern. To provide. Further, a third object of the present invention is to provide a magnetic film for magnetic recording having a large magnetic anisotropy. Finally, a fourth object of the present invention is to provide a structure of a magnetic recording medium that can simplify a laminated structure when a magnetic disk is formed, and is suitable for mass production, and to provide an inexpensive magnetic disk. is there.

[0006] By integrating the above technologies, 40Gb / i
An information recording medium suitable for performing ultra-high density recording exceeding nch ² can be provided.

[0007]

In order to achieve the above object, it is preferred that a magnetic disk having at least a substrate and a magnetic film for information recording be formed of a thin film having at least two magnetic films. Here, the first magnetic layer near the substrate is a ferrimagnetic material, and is a ferromagnetic thin film having an easy axis of magnetization in a direction perpendicular to the substrate surface. This ferromagnetic thin film has no grain boundaries, and moreover,
It is preferably an X-ray amorphous thin film. The second magnetic film has a larger saturation magnetization than the first magnetic film,
In addition, the two magnetic films are preferably magnetically coupled to each other. The second magnetic film is a ferromagnetic thin film having an easy axis of magnetization in a direction perpendicular to the substrate surface, and further, has no crystal grain boundaries in the ferromagnetic thin film. This is a magnetic film for magnetic recording, which is an amorphous thin film. Here, the magnetic anisotropy energy in the plane parallel to the substrate is 1 × 10 ⁴ erg / cm ³ or less, and the magnetic anisotropy energy in the direction perpendicular to the substrate is 1 × 10 ⁷ erg / cm ³ or more. It is preferable to use a certain magnetic film.

In the magnetic film for magnetic recording having such magnetic characteristics, first, the first magnetic film is an amorphous alloy composed of an iron group element and a rare earth element. At least one element selected from the group consisting of Fe, Co and Ni
An alloy thin film composed of at least one element selected from the group consisting of Tb, Gd, Dy, and Ho may be used as the magnetic film for magnetic recording. This magnetic film
It is preferable to use a ferrimagnetic material for the magnetism of the first magnetic film, and it is most preferable that the sublattice magnetization of the iron group element is dominant. The thermal stability of the first magnetic film is represented by KuV / kT (Ku: crystal magnetic anisotropy constant, V: activation volume, k: Boltzmann constant, T: temperature). Among them, the activation volume: V corresponds to the volume in one magnetic domain formed in the magnetic film. Further, since the magnetic anisotropy of this magnetic film is large, the value of KuV / kT is large, and a medium having excellent thermal stability can be obtained. Further, as a magnetostatic characteristic, the saturation magnetization of the first magnetic film is 200 emu / cm.
³ or more, coercive force is ³ kOe or more, and magnetic film thickness is 40 nm
The following is preferred. Next, the second magnetic film is a magnetic thin film of an alloy mainly composed of Co or an oxide of Co, which is selected from Cr, Pt, Pd, Ta, Nb, Si, and Ti. A magnetic film containing at least one type of element is used.

A magnetic disk was formed by preparing a magnetic recording medium including the above-described magnetic film for magnetic recording on a substrate such as glass, resin or Al alloy. Information was recorded or erased by forming magnetic domains of a fixed width and a fixed length on the disk using a magnetic head. Here, the volume of the magnetic domain formed in the magnetic film by recording or erasing of information corresponds to the activation volume. Further, in order to further improve the formation accuracy such as the length and width of the magnetic domain formed on the disk, it is preferable to form the above-described two-layer magnetic film on a circular substrate having an uneven texture on the substrate surface. effective. Due to the undulation of the recording film generated on the recording film due to the texture, the movement of the domain wall during recording or erasing is suppressed, and as a result, the position on the disk of the magnetic domain formed in the magnetic film can be controlled.

It is preferable to configure a magnetic disk drive using the magnetic disk manufactured as described above. The magnetic disk device includes an electric circuit including at least a magnetic disk, a magnetic head, a disk drive system, and a signal processing circuit. A high-density magnetic disk device can be obtained by using a magnetic disk using the above-described magnetic film for magnetic recording in this device. Using this magnetic disk device, various forms of information are recorded on a magnetic film on the disk, and the recorded information is reproduced or erased.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to embodiments. <Embodiment 1> In this embodiment, the magnetic film for recording information is
This is a case where a Tb-Fe-Co amorphous alloy film is used as the first magnetic film and a Co-Cr film is used as the second magnetic film. FIG. 1 shows a schematic diagram of a cross-sectional structure of the magnetic disk thus manufactured. First,
A 2.5 ″ diameter glass substrate was used as the substrate for the magnetic disk (1). The substrate used here is only one example, and the disk substrate of any size can be used.
It goes without saying that even if a metal or resin substrate such as an alloy is used, the effect of the present invention does not depend on the material and size of the substrate used. Further, a NiP film may be formed on a glass, resin, Al or Al alloy substrate by a plating method or the like.

On this substrate (1), a base film (2) was formed for the purpose of protecting the magnetic film and improving the adhesion to the substrate. The material used is a silicon nitride film, and the film thickness is 10 nm. Of course, it is needless to say that this film is not necessarily formed. This film was formed by using a magnetron sputtering method. The target is
Si ₃ N ₄ was used, and Ar was used as a discharge gas. The discharge gas pressure is 10 mTorr, and the input RF power is 1 kW / 150 mmφ. In addition, it goes without saying that a film may be formed by a reactive sputtering method using Si / target as a target and Ar / N ₂ as a discharge gas. Further, it goes without saying that an oxide film such as silicon oxide, a nitride other than silicon nitride, or an oxynitride may be used instead of silicon nitride. The effects of the present invention are not affected by the materials used here.

On this film, a magnetic film consisting of two layers for information recording was formed. Tb ₁₉ Fe as the first magnetic film (3)
_{A 71} Co ₁₀ film was formed by magnetron sputtering. This composition uses a Tb-Fe-Co alloy on the sub-lattice magnetization dominant side of the transition metal as a target and pure Ar as a discharge gas. The thickness of the formed magnetic film is 20 nm. The pressure during sputtering is
5mTorr, input RF power is 1kW / 150mmφ. Where R
Although produced by the F magnetron sputtering method, it goes without saying that the sputtering may be performed by a DC magnetron sputtering method or a sputtering method using electron cyclotron resonance (ECR sputtering method).

Next, a Co ₆₇ Cr ₃₃ film was formed as the second magnetic film (4) so that a magnetic exchange interaction occurred in the first magnetic film. The thickness is 8 nm. This thickness is the thickness at which the exchange coupling force of the first magnetic film is the largest. In order to cause magnetic coupling, it is necessary to continuously form the first Tb-Fe-Co film without breaking the vacuum after forming the first Tb-Fe-Co film. Here, the Co-Cr film does not show good magnetism unless crystallized. To achieve this, the substrate temperature is increased by applying a voltage to bias the particles excited by resonance absorption typified by the ECR sputtering method as a bias and applying uniform energy to the particles to sputter them. The film can be formed without performing. In the case of this system, if the previously formed Tb-Fe-Co magnetic film is overheated, crystallization does not occur, but the magnetic properties change due to structural relaxation. In particular, since the perpendicular magnetic anisotropy energy and the coercive force decrease, it is not preferable to heat the substrate to form a Co—Cr film. Therefore, ECR sputtering is an effective film forming method for forming a crystalline magnetic film at a low temperature, such as a Co-Cr magnetic film.
The sputtering conditions are as follows: the pressure during sputtering is 3 mTorr, and the input microwave power is 1 kW. In addition, a DC bias voltage of 500 V was applied to draw in plasma excited by microwaves. Here, Ar was used as the sputtering gas. Also, here, the Co-Cr type is used as the second magnetic film, but a Co-Cr-Ta or Co-Cr-Pt type may be used.

What is important here is the ratio of the concentration of Co to the concentration of other elements. This ratio determines the perpendicular magnetic anisotropy. In addition, the reason why the Co system is used here is that the saturation magnetization is larger than that of the Fe system. It is 380 emu / cm ³ in the Co-Cr system used here, which is larger than that of the first magnetic film. Here, the value of the saturation magnetization of the first magnetic film was 230 emu / cm ³ . Also,
In the sample of this example having a strong exchange coupling force, it can behave magnetically like a single-layer film.
It was found from the measurement by.

As described above, the material layer having a higher saturation magnetization than the first magnetic film is used as the second magnetic film because the magnetic flux density from the magnetic domain is increased, so that the magnetic head has a large reproduction output. Is obtained.

Finally, a C film having a thickness of 5 nm was formed as a protective film (4). C was used for the target, and Ar was used for the discharge gas. ECR sputtering using microwaves was used for film formation. The pressure during sputtering is 3 mTorr, and the input microwave power is 1 kW. In addition, a DC bias voltage of 500 V was applied to draw in plasma excited by microwaves. Here, Ar is used as the sputtering gas, but it goes without saying that the film may be formed using a gas containing nitrogen. When a gas containing nitrogen is used, the particles become finer, and the obtained C film becomes denser, so that the protection performance can be further improved. Since the film quality of this film greatly depends on such sputtering conditions and the electrode structure, these conditions are not absolute. Here, the ECR sputtering method was used for the production of the protective film, even for a very thin film of 2-3 nm,
This is because a dense and pinhole-free C film with good coverage can be obtained. This is a remarkable difference compared to the RF sputtering method and the DC sputtering method. In addition to this, there is a feature that the damage to the magnetic film when forming the protective film is extremely small. This is because the thinning of the magnetic film progresses as the density increases, so that the deterioration of the magnetic properties due to the damage received during the film formation is fatal. It goes without saying that a DC sputtering method may be used for film formation. However, this method can be used when the thickness of the protective film to be formed is 5 nm or more, but may be unsuitable when the thickness is smaller than 5 nm. This is due to 1) poor coverage of the magnetic film surface, and 2) insufficient density and hardness of the film.

The magnetic characteristics of the magnetic recording medium thus manufactured were measured. From MH loop by VSM, squareness ratio S
And S ^* were both 1.0, and good squareness was obtained.
The coercive force: Hc was 3.5 kOe. In addition, the magnetic anisotropy energy in a plane parallel to the substrate having the magnetic film is
It was 1 × 10 ⁴ erg / cm ³ , and the perpendicular magnetic anisotropy energy in the direction perpendicular to the substrate was 2 × 10 ⁷ erg / cm ³ . When the activation volume of this magnetic recording medium was measured, it was found that the value of the Co-Cr-Pt-based magnetic film widely used as a magnetic recording medium was about 40%.
It was remarkably large by a factor of two. This indicates that this magnetic film is a material having a small thermal fluctuation and a small thermal demagnetization and having excellent thermal stability.

When the structure of the magnetic film was examined by an X-ray diffraction method, only a diffraction peak due to Co-Cr was obtained. In addition, high-resolution transmission electron microscope (high-resolution TEM)
Inspection of the structure and structure of the magnetic film revealed that a clear lattice was found only in the Co-Cr film, which was the second magnetic film. The other films were found to be amorphous or aggregates with an extremely fine structure.

Next, a lubricant was applied to the surface of a magnetic disk using a magnetic recording medium having such magnetic characteristics, and the recording / reproducing characteristics of the disk were evaluated. FIG. 2 schematically shows the configuration of the magnetic disk drive. As the magnetic head (53), a thin-film magnetic head using a soft magnetic film having a high saturation magnetic flux density of 2.1 T was used for recording. In addition, dual spin valve type with giant magnetoresistance effect
Reproduced with a GMR magnetic head. The gap length of the magnetic head is 0.12 μm. The magnetic head is controlled by a drive system (54). The magnetic disk (51) was rotated by the spindle (52), and the distance between the head surface and the magnetic film was kept at 12 nm. When a signal (700 kFCI) corresponding to 40 Gb / inch ² was recorded on this disk and the S / N of the disk was evaluated, a reproduction output of 34 dB was obtained. When the defect rate of this disk was measured, the value was 1 × 10 ⁻⁵ when no signal processing was performed.
It was below.

Here, when the magnetization state of the recorded portion was observed with a magnetic force microscope (MFM), no zigzag pattern peculiar to the magnetization transition region was observed. For this reason, it can be seen that the noise level is significantly lower than that of a normal Co-Cr-Pt magnetic recording medium. FIG. 3 schematically shows this state. In addition, the fact that the magnetic film is amorphous also causes a low noise level. Also, Co
The minute reverse magnetic domains observed between magnetic domains and in the magnetic domains as in the -Cr based magnetic film were not observed in this magnetic film system. This is also one of the causes of low noise from the medium.
One. In the present embodiment, the case where a Tb-Fe-Co system is used for the magnetic film is shown, but in addition to Tb, Gd, Dy, even if one element of Ho is used, Gd-Tb, Gd-Dy, Gd-Ho, Tb-Dy, Tb-H
This is because the same effect can be obtained for o. Furthermore, although Fe-Co alloy was used as the transition metal, Fe-Ni, Co-Ni
Needless to say, such an alloy may be used. <Embodiment 2> This embodiment is a case where a CoO film is used as the second magnetic film. The structure of the manufactured magnetic disk is the same as that of the first embodiment, and a schematic diagram of the structure is as shown in FIG. The film formation method used is a sputtering method, and the conditions for the sputtering and the like are the same as in the first embodiment. Here, the CoO film is formed by a vapor deposition method, but the above-described ECR sputtering method may be used. Using this method, a film can be formed while maintaining the stoichiometry of CoO. The use of the RF sputtering method or the DC sputtering method is not preferable because stoichiometry shifts and magnetic properties change. The conditions for producing CoO by the ECR sputtering method are as follows: the pressure during sputtering is 3 mTorr, and the input microwave power is 1 kW.
In addition, a DC bias voltage of 500 V was applied to draw in plasma excited by microwaves. Here, Ar was used as the sputtering gas. The saturation magnetization of only this CoO film is 450 emu / cm ³ .

The magnetic characteristics of the magnetic recording medium thus manufactured were measured. From the MH loop by VSM, the squareness ratio S and S ^* of the magnetic film obtained by combining the two layers was 1.0, indicating that the magnetic film had good squareness. The coercive force: Hc was 3.5 kOe.
The magnetic anisotropy energy in the plane parallel to the substrate of the magnetic film is 1 × 10 ⁴ erg / cm ³ , and the perpendicular magnetic anisotropy energy in the direction perpendicular to the substrate is 3 × 10 ⁷ erg / cm ³ And a magnetic material having a large magnetic anisotropy in a direction perpendicular to the substrate.
When the activation volume of this magnetic recording medium was measured, it was about 30 times as large as that of a Co—Cr—Pt-based magnetic film widely used as a magnetic recording medium. This indicates that this magnetic film has excellent thermal stability.

Next, a lubricant was applied to the surface of a magnetic disk using a magnetic recording medium having such magnetic characteristics, and the recording / reproducing characteristics of the disk were evaluated. The configuration of the magnetic disk device used is the same as that of the first embodiment, and its schematic diagram is as shown in FIG. The distance between the head and the magnetic recording medium was kept at 12 nm, and a signal (700 kFCI) corresponding to 40 Gb / inch ² was recorded on this disk to evaluate the S / N of the disk. As a result, a reproduction output of 34 dB was obtained. When the defect rate of this disk was measured, the value was 1 × 10 ⁻⁵ or less when no signal processing was performed.

Here, when the magnetization state of the recorded portion was observed with a magnetic force microscope (MFM), no zigzag pattern peculiar to the magnetization transition region was observed. Also, no so-called reverse magnetic domains oriented between the magnetic domains or in the magnetic domains in directions different from the surroundings were observed. For this reason, the noise level was significantly lower than that of a normal Co-Cr-Pt magnetic recording medium. This situation is the same as in the first embodiment, and FIG. 3 schematically shows the situation.

In this embodiment, a two-layer film made of Tb-Fe-Co / CoO is used for the magnetic film. However, the magnetic film has perpendicular magnetic anisotropy in addition to CoO and has a first magnetic film. The same effect can be obtained by using a magnetic film having a larger saturation magnetization. <Embodiment 3> In this embodiment, a case is used in which a substrate having an uneven texture on the substrate surface is used. The texture may be formed by, for example, 1) forming the surface of the substrate at the same time as polishing, or 2) forming an extremely thin island-shaped thin film and using the thin film as the texture. It goes without saying that any of these methods may be used. On this substrate, the same magnetic recording medium as in the first embodiment was formed.

The magnetic characteristics of this magnetic recording medium are described in the embodiment.
Same as 1. The recording and reproduction characteristics of this disk were evaluated using the magnetic disk device shown in FIG. As a result, the noise level was about 1 dB lower than in the first embodiment. this is,
The analysis using MFM shows that the zigzag pattern of the magnetization transition area after recording information became flatter because the domain wall movement was pinned due to the texture unevenness formed on the substrate surface It turned out. Needless to say, this effect does not depend on the magnetic film material used.

[0027]

According to the present invention, a magnetic film composed of two layers magnetically coupled to each other is used, and the first magnetic film is a rare-earth element on the sub-lattice magnetization dominant side of a transition metal having perpendicular magnetic anisotropy. When a magnetic film made of an amorphous alloy made of an iron-group element (RE-TM) alloy is used for a magnetic recording medium, it has a large activation volume and therefore has excellent thermal stability such as thermal demagnetization and small thermal fluctuation. Magnetic recording material can be provided. In addition, RE-TM
Forming a magnetic film having a higher saturation magnetization than the film and having perpendicular magnetic anisotropy on the film has an effect of increasing the output of a reproduction signal. Furthermore, even if the second magnetic film is crystalline, the main first magnetic film is amorphous and is in a temporally coupled state, so that noise due to the medium is reduced. Can be reduced. In addition, since the magnetic film is amorphous, there is no need to form a seed layer for controlling the crystal orientation of the magnetic film, and mass production and low production can be achieved by simplifying the laminated structure of the magnetic recording medium. Effective for pricing. Furthermore, using a substrate having a texture on the surface is effective in improving the accuracy of forming magnetic domains and reducing noise.

With the above technology, a surface recording density exceeding 40 Gb / in ² could be realized.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a cross-sectional structure of a magnetic disk.

FIG. 2 is a diagram showing a configuration of a magnetic disk drive.

FIG. 3 is a schematic view showing a result of observing magnetic domains formed in a magnetic film by MFM.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Underlayer 3 ... 1st magnetic film 4 ... 2nd magnetic film 5 ... Protective film

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koichiro Wakabayashi 1-1-88 Ushitora, Ibaraki City, Osaka Prefecture Inside Hitachi Maxell Co., Ltd. (72) Teruaki Takeuchi 1-188 Ushitora, Ibaraki City, Osaka Hitachi Maxell Inc. F term (reference) 5D006 BB01 BB07 BB08 CB07

Claims (15)

[Claims] 1. A magnetic disk having a substrate and a magnetic film for recording information, wherein the magnetic film comprises at least a first magnetic film near the substrate and a second magnetic film near the magnetic head. Is a ferrimagnetic material, has an easy axis of magnetization in a direction perpendicular to the substrate surface, has no grain boundaries, is an X-ray amorphous ferromagnetic thin film, and the second magnetic film is A magnetic disk having an easy axis of magnetization in a direction perpendicular to the substrate surface and having a larger saturation magnetization than the first magnetic film. 2. The magnetic disk according to claim 1, wherein the first magnetic film and the second magnetic film are magnetically coupled to each other. 3. The magnetic film has an in-plane magnetic anisotropy energy of 1 × 10 ⁴ erg / cm ³ or less in a direction parallel to the substrate, and a magnetic anisotropy energy in a direction perpendicular to the substrate of 1 × 10 ⁴ erg / cm ³ or less. ⁷ er
2. The magnetic disk according to claim 1, wherein the g / cm ^{3 is not} less than g / cm ³ . 4. The magnetic disk according to claim 1, wherein said first magnetic film is an alloy comprising an iron group element and a rare earth element. 5. The iron group element is at least one element selected from the group consisting of Fe, Co, and Ni, and the rare earth element is T
5. The magnetic disk according to claim 4, wherein the magnetic disk is an alloy thin film made of at least one element selected from b, Gd, Dy, and Ho. 6. The magnetic disk according to claim 1, wherein the magnetism of the first magnetic film is a ferrimagnetic material, and the sublattice magnetization of the iron group element is dominant. 7. The thermal stability of the first magnetic film is KuV / kT
(Ku: crystal magnetic anisotropy constant, V: activation volume, k: Boltzmann constant, T: temperature), and the activation volume: V in the first magnetic film is 1 2. The magnetic disk according to claim 1, wherein the magnetic disk corresponds to a volume in one magnetic domain. 8. The saturation magnetization of the first magnetic film is 200 emu / cm ^3.
2. The magnetic disk according to claim 1, wherein the coercive force is 3 kOe or more and the film thickness is 40 nm or less. 9. The second magnetic film is a magnetic thin film of an alloy mainly composed of Co or an oxide of Co, wherein Cr, Pt, P
2. The disk according to claim 1, wherein the disk contains at least one element selected from d, Ta, Nb, Si, and Ti. 10. The magnetic film is made of glass, resin or Al.
A magnetic disk was formed by manufacturing on at least one type of substrate selected from alloys, and information was recorded or erased by forming magnetic domains of a constant width and a constant length on the magnetic disk using a magnetic head. The magnetic disk according to claim 1, wherein: 11. The magnetic disk according to claim 10, wherein a volume in a magnetic domain formed in the magnetic film by recording or erasing the information is the activation volume according to claim 7. 12. The magnetic disk according to claim 1, wherein the magnetic film is formed on a circular substrate having a texture having irregularities on the surface. 13. The magnetic recording medium according to claim 12, wherein the movement of the domain wall during recording or erasing is controlled by the texture of the substrate surface, and the position of the magnetic domain formed on the magnetic film on the disk is controlled. disk. 14. A magnetic disk device comprising at least a magnetic disk, a magnetic head, a disk drive, and an electric circuit, wherein the magnetic disk uses the magnetic film for magnetic recording according to claim 1. A magnetic disk drive characterized in that the magnetic disk drive is constituted by using the above. 15. The magnetic disk drive according to claim 14, wherein various types of information are recorded, reproduced, or erased by using the magnetic disk drive.