JP2615144B2 - Magnetic recording media - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium, and more particularly, to an excellent magnetic recording / reproducing characteristic even in a wide spacing where a distance between a magnetic head and the magnetic recording medium is large. The present invention relates to a magnetic recording medium having a perpendicular magnetic anisotropic film,

[Conventional technology]

In recent years, with an increase in demand for high-density recording, new recording methods have been actively studied. Above all, in the field of magnetic recording, the perpendicular magnetic recording method is being actively studied as one of the promising high-density recording methods.
9, No. 4 (1985), pp. 357-365].

The biggest feature of this perpendicular magnetic recording system is that
This is because the demagnetizing field applied to the recording magnetization decreases as the recording density increases, and the effect of self-demagnetization can be avoided. Therefore, it can be said that the perpendicular magnetic recording system is essentially a system suitable for high-density magnetic recording. However, this perpendicular magnetic recording method is not without its problems.
That is, in the perpendicular magnetic recording system, the distance between the magnetic head and the recording medium (hereinafter, referred to as spacing) has a greater effect on the recording / reproducing characteristics than in the conventional longitudinal recording system, and a narrower spacing is required. The essential superiority of the perpendicular magnetic recording system is maintained only in the area, but in contrast, when the spacing is wide (large), the in-plane recording system tends to be superior in characteristics. The dependence of the spacing is remarkable especially in the combination of the ring head and the single-layer film medium, and has been one of the major problems in putting the perpendicular magnetic recording system to practical use.

[Problems to be solved by the invention]

As described above, the conventional perpendicular magnetic recording medium has a problem that high-density magnetic recording cannot be achieved in the case of a so-called wide spacing in which the distance between the magnetic head and the magnetic recording medium is large.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a magnetic recording medium having a perpendicular magnetic anisotropic film exhibiting excellent recording / reproducing characteristics even in a wide spacing between a magnetic head and a magnetic recording medium. It is to provide a recording medium.

[Means for solving the problem]

The object of the present invention is to form a perpendicular magnetic anisotropic film directly or via an underlayer on a non-magnetic substrate, and directly or via a non-magnetic intermediate layer on this perpendicular magnetic anisotropic film. This is achieved by providing a soft magnetic layer made of a soft magnetic material.

In the magnetic recording medium of the present invention, the magnetic material constituting the perpendicular magnetic anisotropic film is not particularly limited, but is, for example, a perpendicular magnetic anisotropic film made of Co-Cr, Co-O, Fe-O or the like. Alternatively, a perpendicular magnetic anisotropic film in which a magnetic material is filled in alumite micropores can be used.

In the magnetic recording medium of the present invention, the soft magnetic layer provided on the perpendicular magnetic anisotropic film has a thickness in the range of 10 to 100 nm,
Any material having a coercive force of 100 × 10 ³ / (4π) A / m [100 Oe] or less may be used. For example, a single metal such as Ni, Fe or Co or an alloy containing these as a main component, or N
A ferrite film containing i, Fe or Co can be preferably used. Also, if a soft magnetic layer is formed directly on the perpendicular magnetic anisotropic film, the soft magnetic layer may become a hard magnetic layer due to the magnetic coupling between the two layers. The problem is solved by providing a magnetic intermediate layer. When the thickness of the nonmagnetic intermediate layer exceeds 50 nm,
Since the magnetic coupling between them is too weak, the magnetization of the soft magnetic layer does not follow the leakage magnetic field of the perpendicular magnetic anisotropic film, which is not preferable. Further, needless to say, a soft magnetic layer or a non-magnetic underlayer is also provided between the non-magnetic substrate and the perpendicular magnetic anisotropic film to stabilize the recording magnetization or to make the perpendicular magnetic anisotropic film. Needless to say, it is possible to improve the magnetic characteristics of the.

[Action]

The operating principle of the magnetic recording medium of the present invention will be described with reference to FIG. When recording is performed on the magnetic recording medium of the present invention with a magnetic head, the thickness of the soft magnetic layer 1 on the surface is small, so that the magnetic head is relatively easily saturated and the magnetic field distribution of the magnetic head is not largely disturbed. . As a result, the perpendicular magnetic anisotropic film 2 existing under the soft magnetic layer 1 is subjected to perpendicular magnetic recording. Then, the soft magnetic layer 1 is magnetized by the stray magnetic field appearing on the surface of the perpendicular magnetic anisotropic film 2, and the recording pattern of the in-plane magnetization remains on the surface of the magnetic recording medium. Then, when the magnetic head approaches the surface of the medium recorded in this way, the magnetic head detects a magnetic flux from an in-plane recording pattern on the surface of the soft magnetic layer 1 of the medium and obtains a reproduction signal. In this manner, in the magnetic recording medium of the present invention, recording can be performed by high-resolution perpendicular recording, and at the time of reproduction, the in-plane magnetization component is used, thereby increasing the spacing loss during reproduction. Can be reduced. As a result, excellent high-density recording performance and high reproduction output can be obtained even in the field of magnetic recording having a large spacing such as a rigid disk.

The thickness of the soft magnetic layer 1 in the magnetic recording medium of the present invention is preferably in the range of 10 to 100 nm. If the thickness is less than 10 nm, the reproduction output is reduced. Is difficult to penetrate into the perpendicular magnetic anisotropic film 2 so that perpendicular magnetic recording cannot be performed sufficiently. The coercive force of the soft magnetic layer 1 is 100 × 10 ³ / (4
π) A / m or less, preferably 100 × 10 ³ / (4π)
If it exceeds A / m, the magnetization of the soft magnetic layer 1 does not follow the leakage magnetic field from the perpendicular magnetic anisotropic film 2 on which the recording is performed, which causes a remarkable decrease in output, which is not preferable.

〔Example〕

Hereinafter, an example of the present invention will be described in more detail.

Example 1 Ni-P plating with a thickness of 10 μm was applied on an aluminum substrate, and a Ge film (50 nm) for orientation control and a Co ₇₉ Cr ₂₁ film (200 nm) as a perpendicular magnetic anisotropic film were formed thereon. And a Ni ₇₉ Cr ₂₁ film as a soft magnetic layer having a thickness of 0 to 200 n
As shown in Table 1, 1 to 8 types of magnetic recording medium samples were prepared by changing the thickness in a range of m.

The recording / reproducing characteristics of the prepared sample are 0.4μ gap length.
m Mn-Zn ferrite head, 10 kfci and 60 kf
The output at ci was determined and evaluated.

The value of the output (dB) is represented by 0 dB when the film thickness of the permalloy film as the soft magnetic layer is 0, and expressed as a comparative value based on this value. Table 1 shows the results.

As is clear from Table 1, all the magnetic recording media provided with a soft magnetic layer having a thickness of the permalloy film of 10 to 100 nm according to the present invention show excellent reproduction characteristics.

Example 2 Co-O was evaporated on a 40 μm-thick PET (polyethylene terephthalate) substrate while introducing oxygen gas to evaporate Co.
A perpendicular magnetic anisotropic film consisting of
A 350 nm film is formed, and a Co simple film is formed thereon as a soft magnetic layer.
As shown in Table 2, 1 to 7 types of magnetic recording medium samples each having a film thickness of variously changed from 200 nm to 200 nm and further provided with a 50 nm-thick Si film as a protective film were produced.
The method for evaluating the recording / reproducing characteristics of the manufactured sample is the same as that in Example 1, but the spacing with the magnetic head was about 100 nm obtained by adding the average flying height of the head to 50 nm to the thickness of the protective film of 50 nm.
Met. Table 2 shows the results.

As is clear from Table 2, the Co single film of the present invention is
It can be seen that all the magnetic recording media provided within the range of 100 nm show excellent reproduction characteristics.

〔The invention's effect〕

As described in detail above, the magnetic recording medium in which the soft magnetic layer having a predetermined thin film thickness is provided on the perpendicular magnetic anisotropic film of the present invention, the recording pattern of the perpendicular magnetic anisotropic film is applied to the soft magnetic layer. Since the in-plane magnetization component can be transferred and reproduced by the magnetic head, there is an effect that the spacing loss can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the basic configuration and operating principle of the magnetic recording medium of the present invention. 1 Soft magnetic layer 2 Perpendicular magnetic anisotropic film 3 Substrate

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Fumio Kugiya 1-280 Higashi Koikekubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. (72) Mikio Suzuki 1-280 Higashi Koikekubo, Kokubunji-shi, Tokyo Hitachi, Ltd. Inside the Central Research Laboratory

Claims (3)

(57) [Claims] A perpendicular magnetic anisotropic film is formed on a nonmagnetic substrate directly or via an underlayer, and a soft magnetic layer is formed on the perpendicular magnetic anisotropic film directly or via a nonmagnetic intermediate layer. A magnetic recording medium comprising: 2. The magnetic recording medium according to claim 1, wherein the thickness of the soft magnetic layer is in the range of 10 to 100 nm. 3. The magnetic recording medium according to claim 1, wherein the thickness of the soft magnetic layer is in the range of 10 to 100 nm, and the coercive force of the soft magnetic layer is 100 × 10 ³ / (4π) A. / m [100 Oe] or less.