JPH0628652A - Perpendicular magnetic recording medium - Google Patents

Abstract

PURPOSE:To suppress Barkhausen noises by forming a bias magnetic field- imparting film to the surface on the substrate side of a high-permeability magnetic film. CONSTITUTION:The bias magnetic field-imparting film 2 is formed on a substrate 1 and the high-permeability magnetic film 3 is formed thereon. Further, a perpendicularly magnetized film 4 for recording signal magnetization is formed thereon. An exchange interaction acts on the boundary between the bias film 2 and the high-permeability magnetic film 3 and the bias magnetic field is impressed to the magnetic film 3. As a result, the generation of the magnetic walls in the magnetic film 3 is suppressed and the Barkhausen noises are suppressed. A spacing layer, such as antiferromagnetic film, is not formed between the perpendicularly magnetized film 4 and the magnetic film 3 and therefore, the action of the thickness of the antiferromagnetic film as a spacing loss at the time of recording and reproducing does not arise. Consequently, the perpendicular magnetic recording medium having high recording and reproducing efficiency and high resolving power is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a magnetic disk and a VT.
The present invention relates to a perpendicular magnetic recording type magnetic recording medium used for R and the like.

[0002]

2. Description of the Related Art As a perpendicular magnetic recording medium used in a perpendicular magnetic recording system, a perpendicular magnetic film having an easy axis of magnetization in the direction perpendicular to the medium surface is formed on the side distant from the substrate, and a high permeability is formed on the side closer to the substrate. There is a recording medium having a two-layer structure in which a magnetic susceptibility magnetic film is formed (Japanese Patent Laid-Open No. 52-78403), and this two-layer structure perpendicular magnetic recording medium is superior to a recording medium having a perpendicular magnetization film in a single layer. It is known to exhibit characteristics.

However, in the above-described conventional two-layered perpendicular magnetic recording medium, spike noise is observed during recording and reproduction. It has been confirmed that this spike-like noise is not observed when a recording / reproducing experiment is performed using a recording medium having a single-layer structure composed of only a perpendicular magnetization film. It is not caused by the interaction with the perpendicularly magnetized film formed, but only by the high magnetic permeability magnetic film. Further, this spike-like noise does not occur uniformly in the medium, and there are regions where it occurs and regions where it does not occur, and there are many domain walls in the region where spike-like noise occurs, and spike-like noise is generated. The domain wall does not occur in the area where it does not occur. This spike noise is caused by the irreversible transition of the domain wall, and is generally called Barkhausen noise.

From the above, it can be seen that in order to suppress the generation of Barkhausen noise, the generation of the domain wall in the high magnetic permeability magnetic film should be suppressed. In order to effectively suppress the generation of Barkhausen noise, exchange coupling generated at the interface between the ferromagnetic material and the antiferromagnetic material is used to allow the antiferromagnetic film to apply a bias magnetic field to the high permeability magnetic film. A method is known in which the magnetic field is applied and as a result, the generation of magnetic domain walls in the high magnetic permeability magnetic film is suppressed (Japanese Patent Publication No. 3-536).
No. 86). The structure of this perpendicular magnetic recording medium is such that a high-permeability magnetic film is first formed on a substrate, an antiferromagnetic film is formed on this high-permeability magnetic film, and then a perpendicular magnetization is formed on this antiferromagnetic film. A film is formed. It has been shown that Barkhausen noise is surely suppressed during recording / reproduction of the perpendicular magnetic recording medium thus formed.

However, in the above-described structure, since the antiferromagnetic film is formed between the perpendicular magnetization film and the high magnetic permeability magnetic film, the thickness of the antiferromagnetic film acts as a spacing loss during recording and reproduction, As a result, although the recording and reproducing efficiency and the recording resolution are lowered and Barkhausen noise can be suppressed, there is a problem that the sensitivity and the resolution during recording and reproducing are insufficient.

[0006]

As described above, in a perpendicular magnetic recording medium in which a high magnetic permeability magnetic film, a high magnetic permeability magnetic film, an antiferromagnetic film, an antiferromagnetic film and a perpendicular magnetic film are sequentially formed on a substrate. While Barkhausen noise is suppressed during recording / reproduction, an antiferromagnetic film is formed between the perpendicular magnetization film and the high-permeability magnetic film, so the thickness of the antiferromagnetic film reduces the spacing loss during recording / reproduction. As a result, recording and reproducing efficiency and recording resolution are lowered, and Barkhausen noise can be suppressed, but there is a problem that sensitivity and resolution during recording and reproducing are not sufficient.

The present invention provides a perpendicular magnetic recording medium capable of suppressing Barkhausen noise, and having high sensitivity and high resolution recording / reproducing.

[0008]

In order to solve the above-mentioned conventional problems, the present invention provides a substrate, a bias magnetic field applying film formed on the substrate, and a high transparency film formed on the bias magnetic field applying film. It is composed of a magnetic susceptibility magnetic film and a perpendicular magnetization film formed on the high magnetic permeability magnetic film for recording signal magnetization.

[0009]

According to the present invention, since the bias film, the high-permeability magnetic film and the perpendicular magnetic film are sequentially formed on the substrate, exchange interaction works at the interface between the bias film and the high-permeability magnetic film. , A bias magnetic field is applied to this high permeability magnetic film,
As a result, the generation of domain walls in the high-permeability magnetic film is suppressed, and Barkhausen noise can be suppressed.

Further, a high-permeability magnetic film and a perpendicular magnetic film are sequentially formed on the substrate, and regions at both ends of the perpendicular magnetic film in the track width direction are perpendicularly magnetized in mutually opposite directions, whereby the high magnetic permeability of the region is achieved. When the magnetization in the high-permeability magnetic film, which is magnetically coupled to the magnetic film and corresponds to the vertically magnetized region, is fixed in the track width direction (disk radial direction) of the magnetic disk to make it hard to move, the perpendicular magnetic film A bias magnetic field is applied in the track width direction in the high-permeability magnetic film corresponding to the position of the recording / reproducing region 4c between the magnetized regions, and the generation of the domain wall in the high-permeability magnetic film 3 can be suppressed. The magnetic permeability in the track longitudinal direction (disk circumferential direction) in the region of the high magnetic permeability magnetic film that can suppress the generation of Barkhausen noise and corresponds to the position of the recording / reproducing region of the perpendicular magnetization film. , Never causing a decrease in recording efficiency because almost no reduction.

Furthermore, since there is no spacing layer between the perpendicular magnetization film and the high-permeability magnetic film, there is no spacing loss during recording / reproduction, and high recording / reproducing efficiency and high resolution can be obtained. it can.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a vertical sectional view showing the structure of a perpendicular magnetic recording medium according to the first embodiment of the present invention. In this perpendicular magnetic recording medium, a bias magnetic field applying film 2 made of an antiferromagnetic film of FeMn, NiO or the like is formed on a substrate 1 made of an annular disk-shaped disk of aluminum, glass or the like. Permalloy, Fe-based soft magnetic film, or Z
A high-permeability magnetic film 3 made of an r-type amorphous soft magnetic film or the like is formed. Further, a perpendicular magnetic film 4 made of CoCr, CoPt or the like for recording signal magnetization is formed on the high magnetic permeability magnetic film 3.

The bias magnetic field applying film 2 may be a high coercive force magnetic film of CoPt, CoPtCr, CoCr or the like instead of the antiferromagnetic film. Further, as shown in FIG. 2, the bias magnetic field applying film 2 has magnetic films 21 and non-magnetic films 22 alternately laminated, and magnetic films 21 and 21 facing each other laminated with the non-magnetic film 22 interposed therebetween. It may be an artificial lattice film that is antiferromagnetically coupled. This artificial lattice film is composed of, for example, (CoFe / Cu) n, (Co / C) composed of n layers.
u) n, (Fe / Cr) n and the like.

With the above structure, the bias magnetic field applying film 2 and the high magnetic permeability magnetic film 3 are exchange-coupled at the interface, and the bias magnetic field is applied to the high magnetic permeability magnetic film 3. Generation of magnetic domain walls in the high-permeability magnetic film 3 is suppressed, and Barkhausen noise on spikes can be suppressed. Further, since the perpendicular magnetic film 4 is formed directly on the high magnetic permeability magnetic film 3, there is no spacing loss during recording / reproduction, and high resolution and high recording / reproducing efficiency can be obtained.

When the bias magnetic field applying film 2 and the high magnetic permeability magnetic film 3 in this embodiment are formed by the sputtering method or the like, the induced magnetic anisotropy is applied while applying a magnetic field in the recording track width direction of the magnetic recording medium. By imparting the property, the bias magnetic field can be effectively applied to the high magnetic permeability magnetic film 3.

FIG. 3 is a vertical sectional view showing the structure of a perpendicular magnetic recording medium according to the second embodiment of the present invention. In FIG. 3, a nonmagnetic film 5 is provided between the bias magnetic field applying film 2 and the high magnetic permeability magnetic film 3 formed on the substrate 1. Since the strength of the exchange coupling at the interface with the high magnetic permeability magnetic film 3 differs depending on the type of the bias magnetic field applying film 2,
The strength of the bias magnetic field applied to the high-permeability magnetic film 3 also differs. Therefore, if the exchange coupling is too strong, an excessive bias magnetic field is applied to the high magnetic permeability magnetic film 3,
The magnetic permeability μ of the high-permeability magnetic film 3 is reduced and the recording / reproducing efficiency is deteriorated. Therefore, by providing the non-magnetic film 5 between the bias magnetic field applying film 2 and the high-permeability magnetic film 3, the strength of exchange coupling can be adjusted, and the Barkhausen noise can be maintained while maintaining the optimum recording / reproducing sensitivity. Can be suppressed. The type and film thickness of the non-magnetic film 5 may be selected according to various conditions such as the magnetic characteristics and film thickness of the bias magnetic field applying film 2 and the high magnetic permeability magnetic film 3.

FIG. 4 is a vertical sectional view showing the structure of a perpendicular magnetic recording medium according to the third embodiment of the present invention. In FIG. 4, the innermost track 4 on the annular disk-shaped magnetic disk
A bias magnetic field applying film 2 is formed in an annular shape at a corresponding predetermined position outside the recording / reproducing area between 1 and the outermost track 41 ′. This perpendicular magnetic recording medium is manufactured by the following method. That is, first, as shown in FIG. 5A, a bias magnetic field applying film is formed on the substrate 1 by vapor deposition, sputtering or the like. Next, as shown in FIG. 5B, a resist 51 is applied on the bias magnetic field applying film 2,
The area to be the recording / reproducing area of the magnetic recording medium (for example,
The area including the innermost track to the outermost track of the magnetic disk) is masked by the mask 52 and then exposed. Next, as shown in FIG. 5C, a region not exposed by the mask 52 is removed by etching or the like, and as shown in FIG. 5D, after removing the resist 51, the high magnetic permeability magnetic film 3 is formed. And the perpendicular magnetization film 4 is formed by vapor deposition, sputtering, or the like.

Therefore, with the above-mentioned structure, since the bias magnetic field is applied only to the portion of the high magnetic permeability magnetic film 3 facing the bias magnetic field applying film 2, the generation of the domain wall in this portion is suppressed. As a result, the suppression of the domain wall generation in this portion effectively suppresses the generation of the domain wall even in the region where the bias magnetic field is not formed. Therefore, Barkhausen noise due to the generation of domain walls can be suppressed.

In the region of the high magnetic permeability magnetic film 3 on the bias magnetic field applying film 2, recording / reproduction of signal magnetization is not performed in the perpendicular magnetic film 4 corresponding to the region, and the magnetic permeability μ
Therefore, the exchange coupling strength between the bias magnetic field applying film 2 and the high magnetic permeability magnetic film 3 may be increased. Further, in the present embodiment, since the magnetic permeability μ does not decrease in the recording / reproducing area, the magnetic interaction with the magnetic head can be strengthened, and recording / reproducing with high sensitivity and high resolution can be realized. It becomes possible.

Further, in the perpendicular magnetic recording medium according to the present invention, as shown in FIG. 6, an antiferromagnetic film 2'is provided between the high permeability magnetic film 3 and the perpendicular magnetization film 4. Is also good. In this case, the antiferromagnetic film 2'is formed so thin that it does not cause spacing loss.

FIG. 7 is a vertical sectional view showing the structure of a perpendicular magnetic recording medium according to the fourth embodiment of the present invention. The perpendicular magnetic recording medium according to the present embodiment has a high permeability magnetic film 2 on a substrate 1,
The perpendicular magnetization film 3 is formed in order. Further, vertical magnetic regions 4a and 4b having a predetermined width are formed on the inner peripheral side and the outer peripheral side of the perpendicularly magnetized film 4 in the annular disk-shaped magnetic disk. The perpendicularly magnetized regions 4a and 4b are opposite to each other, for example, the vertically magnetized region 4a on the inner circumference side is in the surface direction facing the head from the substrate, and the vertically magnetized region 4b on the outer circumference side is in the substrate direction from the surface facing the head. It is vertically magnetized.

Therefore, the perpendicularly magnetized regions 4a, 4b and the high-permeability magnetic film 3 are magnetically coupled (either exchange coupling due to exchange interaction or magnetostatic coupling may be performed), so that the perpendicularly magnetized regions 4a, 4b. If the magnetization in the high-permeability magnetic film 3 corresponding to 4b is fixed in the track width direction (disk radial direction) of the magnetic disk to make it hard to move, the recording / reproducing area between the perpendicular magnetization areas 4a and 4b in the perpendicular magnetization film 4 will be described. A bias magnetic field indicated by a broken line 71 is applied to the high-permeability magnetic film 3 corresponding to the position 4c, so that the high-permeability magnetic film 3 is formed.
Since it is possible to suppress the generation of magnetic domain walls inside, it is possible to suppress the generation of Barkhausen noise. Further, since the magnetic permeability in the track longitudinal direction (disc circumferential direction) in the region of the high magnetic permeability magnetic film 3 corresponding to the position of the recording / reproducing region 4c of the perpendicular magnetization film 4 hardly decreases, the recording / reproducing efficiency is improved. It does not cause deterioration. Furthermore, since a spacing layer such as an antiferromagnetic film is not formed between the high-permeability magnetic film 3 and the perpendicular magnetic film 4, high recording / reproducing efficiency is achieved.
Moreover, a high-resolution perpendicular magnetic recording medium can be realized.

8 to 13 show other modifications of the perpendicular magnetic recording medium according to the present invention. The perpendicular magnetic recording medium shown in FIG. 8 has a non-magnetic film 5 formed between a high-permeability magnetic film 3 and a perpendicular magnetic film 4. That is, at the interface between the high-permeability magnetic film 3 and the perpendicular magnetic film 4, the non-magnetic film 5 to the position corresponding to the recording / reproducing region 4c of the perpendicular magnetic film 4 to the extent that the exchange coupling at the interface can be cut off.
Are formed.

Therefore, the high permeability magnetic film 3 and the perpendicular magnetization film 4 are formed.
Since they can be magnetostatically coupled at the interface corresponding to the recording / reproducing area 4c, the high magnetic permeability magnetic film 3 is deteriorated by the signal magnetization even when the high magnetic permeability magnetic film 3 is thinned as necessary. It is possible to realize good recording and reproduction without any trouble.

The perpendicular magnetic recording medium shown in FIG.
A high permeability magnetic film 3 and a perpendicular magnetization film 4 are formed on the top. The high coercive force magnetic films 6a, 6 magnetized in the track width direction and oriented in the longitudinal direction are formed on the inner peripheral side and the outer peripheral side of the perpendicularly magnetized film 4 in the annular disk-shaped magnetic disk.
Since b is formed with a predetermined width, the high magnetic permeability magnetic film 3 and the high coercive force magnetic films 6a and 6b can be magnetically coupled, and the same effect can be obtained.

The perpendicular magnetic recording medium in FIG. 10 has high coercive force magnetic films 6a, 6 magnetized in the track width direction and oriented in the longitudinal direction on the inner and outer peripheral sides of the substrate 1.
b is formed, and the high magnetic permeability magnetic film 3 is formed at a position corresponding to the recording / reproducing area between the high coercive force magnetic films 6a and 6b. Further, on the high magnetic permeability 3 and the high coercive force magnetic films 6a and 6b, a perpendicular magnetization film 4 for recording and reproducing signal magnetization is formed. Also in this case, the bias magnetic field can be applied to the high magnetic permeability magnetic film 3 in the direction of the broken line 101 by the magnetization of the high coercive force magnetic films 6a and 6b in the same direction, and the same effect can be obtained.

In the perpendicular magnetic recording medium shown in FIG. 11, the second high magnetic permeability magnetic film 3 ', the non-magnetic film 5 on the substrate 1, the high coercive force magnetic films 6a, 6b and the first magnetic film 5 on the non-magnetic film 5. The high magnetic permeability magnetic film 3 is sequentially formed, and the perpendicular magnetization film 4 is formed on the high coercive force magnetic films 6a and 6b and the first high magnetic permeability magnetic film 3. Therefore, when the high coercive force magnetic films 6a and 6b and the high magnetic permeability magnetic film 3 ′ are magnetostatically coupled, the high coercive force magnetic film 6a → the high magnetic permeability magnetic film 3 → the high coercive force magnetic film 6b → A closed magnetic circuit with a small magnetic circuit resistance (broken line 111) having a high magnetic permeability magnetic film 3 '(or vice versa) is formed, and a bias magnetic field stronger and more effective than that of the perpendicular magnetic recording medium shown in FIG. 9 is applied. Will be able to.

In the perpendicular magnetic recording medium shown in FIG. 12, a high coercive force magnetic film 6, a nonmagnetic film 5, a high magnetic permeability magnetic film 3 and a perpendicular magnetization film 4 are sequentially formed on a substrate 1. Further, since the high coercive force magnetic film 6 and the high magnetic permeability magnetic film 3 are magnetostatically coupled, a bias magnetic field is applied to the high magnetic permeability magnetic film 3 in the track width direction.

In the perpendicular magnetic recording medium shown in FIG. 13, a high-permeability magnetic film 3 and a perpendicular magnetization film 4 are sequentially formed on a substrate 1, and magnetized in opposite directions to the medium surface perpendicular direction at positions of both ends of a recording / reproducing area. Permanent magnets 7a and 7b are provided. Therefore, a bias magnetic field in the track width direction can be applied to the high magnetic permeability magnetic film 3 as in the above example. Note that high coercive force magnetic films 6a and 6b may be used instead of the permanent magnets 7a and 7b.

In the present invention, the perpendicular magnetic film to be recorded with signal magnetization is formed only on one disk-shaped surface of a magnetic disk or the like, but the present invention is not limited to this, and the other surface is formed. May also be formed. Further, in each of the examples, a disk-shaped perpendicular magnetic recording medium such as a magnetic disk is shown, but the present invention can be applied to a tape-shaped perpendicular magnetic recording medium such as a magnetic tape.

[0032]

As described above, according to the present invention, it is possible to suppress the generation of the domain wall in the high magnetic permeability magnetic film, and the effect of Barkhausen noise generated at the interface between the high magnetic permeability magnetic film and the perpendicular magnetization film can be obtained. Can be suppressed. Further, since a spacing layer such as an antiferromagnetic film is not formed between the perpendicular magnetization film and the high magnetic permeability magnetic film, the thickness of the antiferromagnetic film does not work as a spacing loss during recording / reproduction, As a result, a perpendicular magnetic recording medium with high recording / reproducing efficiency and high resolution can be realized.

[Brief description of drawings]

FIG. 1 is a diagram showing the configuration of a perpendicular magnetic recording medium according to a first embodiment of the invention.

FIG. 2 is a diagram showing an example of a bias magnetic field applying film in FIG.

FIG. 3 is a diagram showing the configuration of a perpendicular magnetic recording medium according to a second embodiment of the invention.

FIG. 4 is a diagram showing the configuration of a perpendicular magnetic recording medium according to a third embodiment of the invention.

FIG. 5 is a diagram showing a manufacturing process of the perpendicular magnetic recording medium in FIG.

FIG. 6 is a diagram showing a modification of the configuration of the perpendicular magnetic recording medium according to the present invention.

FIG. 7 is a diagram showing the structure of a perpendicular magnetic recording medium according to a fourth embodiment of the invention.

FIG. 8 is a diagram showing a modification of the configuration of the perpendicular magnetic recording medium according to the present invention.

FIG. 9 is a diagram showing a modification of the configuration of the perpendicular magnetic recording medium according to the present invention.

FIG. 10 is a diagram showing a modification of the configuration of the perpendicular magnetic recording medium according to the present invention.

FIG. 11 is a diagram showing a modification of the configuration of the perpendicular magnetic recording medium according to the present invention.

FIG. 12 is a diagram showing a modification of the configuration of the perpendicular magnetic recording medium according to the present invention.

FIG. 13 is a diagram showing a modification of the configuration of the perpendicular magnetic recording medium according to the present invention.

[Explanation of symbols]

 1 substrate 2 bias magnetic field applying film 3 high permeability magnetic film 4 perpendicular magnetization film 5 non-magnetic film 6a, 6b high coercive force magnetic film 7a, 7b permanent magnet 21 magnetic film 22 non-magnetic film 41 innermost track 41 'outermost circumference Track 51 Resist 52 Mask

Claims (6)

[Claims] 1. A perpendicular magnetic recording medium comprising a substrate, a high-permeability magnetic film formed on the substrate, and a perpendicular magnetic film for recording signal magnetization formed on the high-permeability magnetic film. A perpendicular magnetic recording medium, wherein a bias magnetic field applying film is formed on at least the surface of the high magnetic permeability magnetic film on the substrate side. 2. The perpendicular magnetic recording medium according to claim 1, wherein a non-magnetic film is formed between the bias magnetic field applying film and the high magnetic permeability magnetic film. 3. The perpendicular magnetic recording medium according to claim 1, wherein the bias magnetic field applying film is an antiferromagnetic film. 4. The perpendicular magnetic recording medium according to claim 1, wherein the bias magnetic field applying film is a high coercive force magnetic film having in-plane orientation. 5. The bias magnetic field applying film is a laminated film composed of at least two magnetic films in which a magnetic film and a nonmagnetic film are alternately laminated, and a relative film laminated with the nonmagnetic film interposed therebetween. The perpendicular magnetic recording medium according to claim 1 or 2, wherein the facing magnetic films are antiferromagnetically coupled. 6. A perpendicular magnetic recording medium comprising a substrate, a high-permeability magnetic film formed on the substrate, and a perpendicular magnetic film for recording signal magnetization formed on the high-permeability magnetic film. A perpendicular magnetic recording medium, wherein predetermined regions at both ends of a recording / reproducing region of the perpendicular magnetization film are perpendicularly magnetized in opposite directions.