JPH0567320A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To attain a high density recording and a loss noise by making a vertical magnetic anisotropy by weakening a magnetic anisotropy having more an easy magnetization direction in a magnetic recording direction at the upper part of the magnetic film than at the lower part of the magnetic film or by having an easy magnetization direction in a horizontal surface, having an isotropy in the horizontal surface or having a vertical magnetic anisotropy and constituting these successively and continuously or by multistages. CONSTITUTION:In the magnetic film 18, the lower part of the magnetic film 18, namely a portion near the substrate 10 has a magnetic anisotropy having an easy magnetization direction in the magnetic recording direction. The magnetic isotropy in a magnetic recording direction is gradually weakened in accordance with approaching to time upward, namely to the surface. And it has gradually more an easy magnetization direction towards the upper side and a magnetization direction towards the upper side and a magnetic isotropy in the horizontal surface. When it consists of a magnetic film 24 in place of the magnetic film 18, the magnetic film 24 is constituted with a lower magnetic film 20 and a upper magnetic film 24 and the lower magnetic film 20 has a magnetic isotropy having an easy magnetization direction in the magnetic recording direction. The upper magnetic film 22 is magnetic isotropic. Those are constituted successively and continuously or by multistages.

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 used for, for example, a hard magnetic disk, and more particularly to a magnetic recording medium capable of high density recording and realizing low noise.

[0002]

2. Description of the Related Art Conventionally, as a structure of a magnetic recording medium for high density recording, a structure as shown in FIG. 3 is known. Figure 3
The magnetic recording medium 33 shown in FIG. 2 has a base film 12 and a magnetic film 14 laminated on a substrate 10 formed by coating molded aluminum or aluminum alloy with NiP plating or the like.
And a protective film 16. The magnetic film 14 is a thin film of Co-Ni, Co-Ni-Cr or the like having a thickness of about 700 Å, and the protective film 16 is a thin film of C or the like.

[0003]

In the magnetic recording medium, if the magnetic film is thick, the recording magnetic field does not sufficiently reach the lower part of the magnetic film during recording, and the upper part of the magnetic film is magnetized, but The lower part of the film may not be sufficiently magnetized. Therefore, it is known that the magnetic film is made thinner as a means for further increasing the high density recording of the magnetic recording medium.

However, when the magnetic film is thinned, the boundary between the magnetic domains of the magnetic film becomes zigzag (zigzag magnetic domain).
Is more likely to occur. When this zigzag phenomenon occurs, bit interference or read error is likely to occur at the time of reading information (especially a digital signal) because the boundaries of magnetic domains are not clear. This hinders high density recording and noise reduction of the magnetic recording medium.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a magnetic recording medium in which the generation of zigzag magnetic domains is reduced even with a thinned magnetic film.

[0006]

A magnetic recording medium according to claim 1, wherein a base film, a magnetic film and a protective film are laminated on a substrate, the lower part of the magnetic film being magnetized in the magnetic recording direction. It is characterized in that it has a magnetic anisotropy having an easy direction and weakens the magnetic anisotropy of the magnetic film in the magnetic recording direction as the distance from the substrate increases.

According to a second aspect of the present invention, there is provided a magnetic recording medium in which a base film, a magnetic film and a protective film are laminated on a substrate, wherein the magnetic film comprises a lower magnetic film and an upper magnetic film.
The lower magnetic film has a magnetic anisotropy having an easy magnetization direction in the magnetic recording direction, and the upper magnetic film has a weaker magnetic anisotropy in the magnetic recording direction than the lower magnetic film.

According to a third aspect of the present invention, there is provided a magnetic recording medium in which a base film, a magnetic film, and a protective film are laminated on a substrate, wherein the magnetic film has a magnetic anomalous direction having an easy magnetization direction in a lower magnetic recording direction. It is characterized in that it has anisotropy, has an easy magnetization direction in the horizontal plane of the magnetic recording medium as it moves away from the substrate, and has magnetic isotropy in the horizontal plane.

According to a fourth aspect of the present invention, there is provided a magnetic recording medium in which a base film, a magnetic film and a protective film are laminated on a substrate, wherein the magnetic film comprises a lower magnetic film and an upper magnetic film.
The lower magnetic film has magnetic anisotropy having an easy magnetization direction in the magnetic recording direction, and the upper magnetic film has an easy magnetization direction in the horizontal plane of the magnetic recording medium and has magnetic isotropy in the horizontal plane. It is a feature.

According to a fifth aspect of the present invention, there is provided a magnetic recording medium in which a base film, a magnetic film, and a protective film are laminated on a substrate, and the magnetic film has a magnetic anomalous direction having an easy magnetization direction in a lower magnetic recording direction. It is characterized in that it has anisotropy and has magnetic isotropy with increasing distance from the substrate.

According to a sixth aspect of the present invention, there is provided a magnetic recording medium in which a base film, a magnetic film and a protective film are laminated on a substrate, wherein the magnetic film comprises a lower magnetic film and an upper magnetic film.
The lower magnetic film has a magnetic anisotropy having an easy magnetization direction in the magnetic recording direction, and the upper magnetic film has a magnetic isotropy.

According to a seventh aspect of the present invention, there is provided a magnetic recording medium in which a base film, a magnetic film, and a protective film are laminated on a substrate, wherein the magnetic film has a magnetic anisotropy in a magnetic recording direction at a lower part thereof. It is characterized in that it has anisotropy and has perpendicular magnetic anisotropy with increasing distance from the substrate.

The magnetic recording medium according to claim 8 is a magnetic recording medium in which a base film, a magnetic film, and a protective film are laminated on a substrate, wherein the magnetic film comprises a lower magnetic film and an upper magnetic film.
The lower magnetic film has magnetic anisotropy having an easy magnetization direction in the magnetic recording direction, and the upper magnetic film is a perpendicular magnetization film.

In the present invention, the magnetic recording direction means the circumferential direction when the magnetic recording medium is a disc, and the running direction of the tape when the magnetic recording medium is a tape. ..

[0015]

In the magnetic recording medium of the present invention, the magnetic anisotropy having an easy magnetization direction in the magnetic recording direction is provided below the magnetic film, but above the magnetic film, the magnetic anisotropy is weakened more than in the lower plane. The width of the zigzag of the zigzag magnetic domain is narrowed by having an easy magnetization direction inside and making it either isotropic, isotropic, or perpendicular magnetic anisotropy in the horizontal plane.

[0016]

【Example】

Example 1 A magnetic recording medium of Example 1 will be described with reference to FIG. The magnetic recording medium 31 is formed by coating the formed aluminum or aluminum alloy with NiP plating or the like, and forming the underlying film 12 and the magnetic film 1 laminated on the substrate 10.
8 and the protective film 16 form a schematic structure. The magnetic film 18 is Co
It is composed of a thin film of -Ni, Co-Ni-Cr, or the like. The material of the protective film 16 is a thin film of C or the like and fluorocarbon or the like applied thereon.

Here, in the magnetic film 18 of Example 1,
A lower portion of the magnetic film 18, that is, a portion close to the substrate 10 has magnetic anisotropy having an easy magnetization direction in the magnetic recording direction. The magnetic anisotropy in the magnetic recording direction is gradually weakened as it goes upward, that is, as it approaches the surface.

For forming the base film 12, the magnetic film 18, and the protective film 16, various thin film forming methods such as a vacuum deposition method, a sputtering method, an ion beam deposition method and an ion plating method can be applied.

The magnetic anisotropy of the magnetic film 18 can be changed by changing the heating conditions and the atmospheric gas (eg, Ar gas) when the magnetic film 18 is formed.

(Example 2) The magnetic recording medium of Example 2 is different from the magnetic recording medium of Example 1 only in the magnetization state of the magnetic film. Therefore, as in Example 1, only the differences will be described with reference to FIG. To do.

The magnetic film 18 of the magnetic recording medium 31 of the second embodiment has a magnetic anisotropy in which the magnetic film 18 has an easy magnetization direction in the magnetic recording direction. The magnetic recording medium gradually has an easy magnetization direction in the horizontal direction and has magnetic isotropy in the horizontal plane.

(Example 3) Since the magnetic recording medium of Example 3 is different from the magnetic recording medium of Example 1 only in the magnetization state of the magnetic film, only the different points will be described with reference to FIG. 1 as in Example 1. To do.

The magnetic film 18 of the magnetic recording medium 31 of the third embodiment has a magnetic anisotropy having an easy magnetization direction in the magnetic recording direction below the magnetic film 18. Then, it gradually becomes magnetically isotropic in the upward direction. The difference from the magnetic film 18 of Example 2 is that it is not limited to the horizontal plane.

(Example 4) The magnetic recording medium of Example 4 is different from the magnetic recording medium of Example 1 only in the magnetization state of the magnetic film. Therefore, like Example 1, only the differences will be described with reference to FIG. To do.

The magnetic film 18 of the magnetic recording medium 31 of the fourth embodiment has a magnetic anisotropy having an easy magnetization direction in the magnetic recording direction below the magnetic film 18. The vertical magnetic anisotropy gradually increases in the upward direction.

Example 5 A magnetic recording medium of Example 5 will be described with reference to FIG. The magnetic recording medium 32 has a schematic structure including a base film 12, a magnetic film 24, and a protective film 16 which are formed by coating a molded aluminum or aluminum alloy with NiP or the like and laminating it on the substrate 10. Magnetic film 18
Is a thin film made of Co-Ni, Co-Ni-Cr, or the like. The material of the protective film 16 is a thin film of C or the like and fluorocarbon or the like applied thereon.

The magnetic film 24 of Example 5 is the lower magnetic film 2.
0 and the upper magnetic film 22. Further, the lower magnetic film 20
Has magnetic anisotropy with an easy magnetization direction in the magnetic recording direction. The upper magnetic film 22 also has magnetic anisotropy having an easy magnetization direction in the magnetic recording direction, but this is weaker than the magnetic anisotropy of the lower magnetic film 20.

For forming the base film 12, the magnetic film 24, and the protective film 16, various thin film forming methods such as a vacuum vapor deposition method, a sputtering method, an ion beam deposition method and an ion plating method can be applied. The lower magnetic film 20 and the upper magnetic film 22 can be formed in multiple stages by repeating the above method.

In order to change the magnetic anisotropy, the heating conditions and the atmospheric gas (eg, Ar gas) at the time of forming the lower magnetic film 20 and the upper magnetic film 22 are changed, and the material is changed. Can be implemented in.

Example 6 Since the magnetic recording medium of Example 6 is different from the magnetic recording medium of Example 5 only in the magnetized state of the magnetic film, only the different points will be described with reference to FIG. 2 as in Example 5. To do.

The magnetic film 24 of Example 6 is the lower magnetic film 2.
0 and the upper magnetic film 22. Further, the lower magnetic film 20
Has magnetic anisotropy with an easy magnetization direction in the magnetic recording direction. The upper magnetic film 22 has a direction of easy magnetization in the horizontal plane and is magnetically isotropic in the horizontal plane.

(Embodiment 7) The magnetic recording medium of Embodiment 7 is different from the magnetic recording medium of Embodiment 5 only in the magnetization state of the magnetic film. Therefore, like Embodiment 5, only the differences will be described with reference to FIG. To do.

The magnetic film 24 of Example 7 is the lower magnetic film 2.
0 and the upper magnetic film 22. Further, the lower magnetic film 20
Has magnetic anisotropy with an easy magnetization direction in the magnetic recording direction. The upper magnetic film 22 is magnetically isotropic. The difference from Example 6 is that it is not limited to the horizontal plane.

(Example 8) The magnetic recording medium of Example 8 is different from the magnetic recording medium of Example 5 only in the magnetization state of the magnetic film. Therefore, like Example 5, only the differences will be described with reference to FIG. To do.

The magnetic film 24 of Example 8 is the lower magnetic film 2.
0 and the upper magnetic film 22. Further, the lower magnetic film 20
Has magnetic anisotropy with an easy magnetization direction in the magnetic recording direction. The upper magnetic film 22 is composed of a perpendicular magnetic film.

In the above embodiment, the magnetic state of the magnetic film is continuous or has a two-layer structure. However, by adopting a multi-layer structure of three layers or more, the magnetic states below and above the magnetic film are made different. However, of course, it is preferable.

In any of the magnetic recording media having the structures shown in Examples 1 to 8, the zigzag width of the zigzag magnetic domain can be reduced, read errors hardly occur, and high density recording and low noise are possible. It is what

[0038]

The magnetic recording medium of the present invention has magnetic anisotropy having an easy magnetization direction in the magnetic recording direction below the magnetic film, but magnetic anisotropy in the magnetic recording direction above the magnetic film rather than below. Weaken the direction or have an easy magnetization direction in the horizontal plane,
In addition, by making it isotropic in the horizontal plane or isotropic, or by making perpendicular magnetic anisotropy, and by making these sequentially or in multiple steps, the magnetic film was made thinner. Even when the zigzag magnetic domains are generated, the width of the zigzag is narrowed.

Therefore, the magnetic recording medium of the present invention, which is extremely less affected by the zigzag magnetic domains, is less likely to cause a read error and has improved high density recording and low noise.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of magnetic recording media of Examples 1 to 4.

FIG. 2 is a cross-sectional view of magnetic recording media of Examples 5-8.

FIG. 3 is a cross-sectional view of a conventional magnetic recording medium.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Substrate 12 Underlayer film 14 Magnetic film 16 Protective film 18 Magnetic film 20 Lower magnetic film 22 Upper magnetic film 24 Magnetic film 31 Magnetic recording medium 32 Magnetic recording medium 33 Magnetic recording medium

Claims (8)

[Claims] 1. A magnetic recording medium comprising a base film, a magnetic film and a protective film laminated on a substrate, wherein the lower part of the magnetic film has magnetic anisotropy having an easy magnetization direction in the magnetic recording direction, A magnetic recording medium characterized in that the magnetic anisotropy of the magnetic film in the magnetic recording direction weakens as the distance increases. 2. A magnetic recording medium comprising a base film, a magnetic film, and a protective film laminated on a substrate, wherein the magnetic film comprises a lower magnetic film and an upper magnetic film, and the lower magnetic film has an easy magnetization direction in the magnetic recording direction. The magnetic recording medium is characterized in that the upper magnetic film has a weaker magnetic anisotropy in the magnetic recording direction than the lower magnetic film. 3. A magnetic recording medium comprising a base film, a magnetic film and a protective film laminated on a substrate, wherein the magnetic film has magnetic anisotropy having an easy magnetization direction in the magnetic recording direction at the bottom, A magnetic recording medium which has a direction of easy magnetization in a horizontal plane of the magnetic recording medium with increasing distance and has magnetic isotropy in the horizontal plane. 4. A magnetic recording medium comprising a base film, a magnetic film, and a protective film laminated on a substrate, wherein the magnetic film comprises a lower magnetic film and an upper magnetic film, and the lower magnetic film has an easy magnetization direction in the magnetic recording direction. A magnetic recording medium having a magnetic anisotropy with, the upper magnetic film having an easy magnetization direction in a horizontal plane of the magnetic recording medium, and having magnetic isotropy in the horizontal plane. 5. A magnetic recording medium comprising a base film, a magnetic film and a protective film laminated on a substrate, wherein the magnetic film has magnetic anisotropy having an easy magnetization direction in the magnetic recording direction at the lower part, A magnetic recording medium having magnetic isotropy with increasing distance. 6. A magnetic recording medium comprising a base film, a magnetic film and a protective film laminated on a substrate, wherein the magnetic film comprises a lower magnetic film and an upper magnetic film, and the lower magnetic film has an easy magnetization direction in the magnetic recording direction. A magnetic recording medium characterized by having magnetic anisotropy with, and an upper magnetic film having magnetic isotropy. 7. A magnetic recording medium comprising a base film, a magnetic film and a protective film laminated on a substrate, wherein the magnetic film has magnetic anisotropy having an easy magnetization direction in the magnetic recording direction at the bottom, A magnetic recording medium having perpendicular magnetic anisotropy with increasing distance. 8. A magnetic recording medium comprising a base film, a magnetic film, and a protective film laminated on a substrate, wherein the magnetic film comprises a lower magnetic film and an upper magnetic film, and the lower magnetic film has an easy magnetization direction in the magnetic recording direction. A magnetic recording medium characterized by having magnetic anisotropy with, and the upper magnetic film being a perpendicularly magnetized film.