JPS60231306A - Amorphous magnetooptical layer - Google Patents

Abstract

PURPOSE:To increase Kerr rotation angle thetaK in an amorphous alloy magnetic material and thereby to improve optical reproduction characteristics, by employing a material consisting essentially of Tb-Fe-Co-M which has an easy magnetization axis perpendicular to the film plane. CONSTITUTION:An amorphous magnetooptical layer is employed which is made of a material consisting essentially of Tb-Fe-Co-M (wherein M is at least one element selected from among Sn, Bi, Ni, Cr and Cu) and which has an easy magnetization axis perpendicular to the film plane. This magnetic layer needs to have perpendicular magnetic anisotropy and preferably has high coercive force. When the composition of the magnetic material constituting the magnetic layer is expressed by {Tbx(Fe1-yCoy)1-x}1-zMz, it is preferable to meet the conditions of 0.1<=x<=0.4, 0.01<=y<=0.5, and 0.002<=z<=0.1. The amorphous magnetooptical layer is formed on an appropriate carrier so that the film thickness becomes about 0.01-1mum by an appropriate method such as vacuum deposition, sputtering, or ion plating.

Description

Detailed Description of the Invention Technical Field The present invention relates to a magneto-optic layer of a magneto-optical recording medium used for hard disks, floppy disks, document files, etc., and in particular to an amorphous magneto-optic layer with excellent magneto-optic effects. This is related to.

BACKGROUND OF THE INVENTION In recent years, various types of magneto-optical recording media for performing magnetic recording using semiconductor laser light have been developed for use in high-density recording. In particular, in order to be used for high-density recording, a magnetic film is required to have an axis of easy magnetization in a direction perpendicular to the film surface. Conventionally, magnetic films used in these magneto-optical recording media include Gd-Co, Gd-Fe, Tb-Fe,
Gd-Tb-Fe.

Magneto-optical recording media using amorphous alloys such as Tb-Dy-Fe are known, but magneto-optical recording media using these amorphous alloy magnetic materials have high recording sensitivity and can be recorded at high speeds (frequency) using semiconductor laser light. , ti, MH,), but has the problem that the magneto-optical effect is not fully satisfactory. Therefore, it has been proposed to increase the Kerr rotation angle θK and improve the magneto-optic effect by using a ternary amorphous magnetic alloy film made of Tb-F.-Co. To make a magneto-optical recording medium using such an amorphous alloy magnetic material, the magnetic material is generally deposited on a substrate such as a glass plate by a method such as vacuum deposition or sputtering to form a magnetic film. There is. Recording and reproduction on the magneto-optical recording medium thus obtained is performed as follows. In other words, recording is performed by heating the magnetic film by irradiating a laser beam modulated with an information signal, taking advantage of the characteristics of the magnetic film's rapid change in coercive force in response to temperature changes near the Curie temperature or the compensation temperature. This is done by reversing the direction of magnetization. Further, reproduction is performed by reading out the Kerr rotation angle of the magnetic film recorded in this way. In this way, the Kerr effect is used to record and reproduce information signals in cases where light is difficult to pass through, such as in amorphous alloy magnetic materials.

The Kerr effect is the rotation of the plane of polarization when light is reflected on the surface of a magnetic material fj4. elephant, &) polar effect, b
) vertical (1ong1tudinal) effect, C) horizontal (t
In particular, in the case of an amorphous alloy magnetic material, the polar effect of a is used, and reproduction is performed using the Kerr rotation angle θK. Therefore, Kerr rotation angle θK
If the value becomes even slightly larger, the magneto-optical effect increases accordingly.
This results in improved playback characteristics.

However, the Kerr rotation angle θ of the above-mentioned Tb-Fe-Co ternary amorphous alloy magnetic material is about 0.81 or 0.33 depending on its composition, and it is desired to improve the optical reproduction characteristics. The current situation is

Purpose The purpose of the present invention is to further increase the Kerr rotation angle θK in an amorphous alloy magnetic material having an axis of easy magnetization perpendicular to the film surface, thereby improving optical reproduction characteristics. Our goal is to provide the following.

Structure The present invention utilizes a Tb-
Fe-Co-M (M is Sn, Bi.

This is an amorphous magneto-optical layer made of at least one material selected from Nl, Cr, and Cu. The magnetic layer of the present invention must have perpendicular magnetic anisotropy and preferably have a high coercive force. For this reason, the composition formula of the magnetic material constituting the magnetic layer of the present invention is (Tbx ( "x-yCGy)t-x)14Mz When expressed as 0.1 <, x≦O14, 0,0
It is preferable that 1≦y<, O-'so, ooz≦2≦0.1.

The amorphous magneto-optical layer of the present invention is vacuum deposited on a suitable support.
It is formed to a film thickness of about 0.01-IItm by sputtering, ion silating, or other methods.

When forming a thin film of magnetic material by sputtering,
Each magnetic material component is used individually or in combination as a target, and the magnetic material composition is controlled by the area ratio of the target surface.

As the support, glass, plastic, ceramic, etc. can be used. Further, a protective layer, a heat insulating layer, a reflective layer, etc. may be optionally provided between the amorphous magneto-optical layer of the present invention and the support or on the upper surface.

Effect Tb-Fe-Co-M obtained in this way (M is Sn, Bi, Ni, Or, Cu
Since the rotation angle θK of the amorphous magneto-optic layer having a perpendicular easy axis of magnetization consisting of at least 1 m) is larger than that of a layer not containing M, the optical reproduction characteristics during optical reproduction are As a result, the S/N ratio improves and the number of recording bits increases, resulting in a magneto-optical recording medium capable of high-density recording and reproduction.

Examples are shown below.

5 Example: Tb was deposited on a slide glass support by sputtering.
An amorphous magneto-optical layer made of -F.-Co-M was formed. The target was Fe6. . co
A film was formed by placing Tb and M chips on an alloy disk (2) and controlling each composition ratio by the area ratio of the target surface.

The preparation conditions for each magnetic film are shown in the table below.

(Left below) 6 - Each amorphous magneto-optic layer has a compensation composition with a large coercive force He (Flo, 9 C00J )0.8 Tbo, t or (Feo, s COo, t ) o, yo Tbo
, in the composition of tt, Tb is partially replaced by M, i.e. (Fe1), @Coo,t )o, s(
TbI-xMx)o,t*(Fe61gC
o6, 1) o, yo (Tbt-xMx) o, goose t
or (FeO, Q Cog, 1 ) o, tt ((
Tbo, uMoAa)rxMx)o, and tt were prepared.

Film evaluation was performed using a He-No laser (
λ=633 nm), and the Kerr rotation angle θ and coercive force Ha were determined using the Kerr effect.

The results are shown in Figs. 1 to 1θ. From these figures, it can be seen that by increasing the amount of X, that is, M, Ha becomes smaller, but θ becomes larger. In each example, a part of Tb was replaced with M, so when the amount of M was increased, the charge of Tb that contributed to the anisotropy was reduced, and Ha became smaller, so the amount of M could not be increased that much. Feo
, e Coo, 1) and by increasing the amount of M while keeping the ratio of the amount of Tb constant, the decrease in Hc can be suppressed to some extent and the amount of M can be increased.

Here again, in each example, Tb-Fe when the Kerr rotation angle θK is the largest in the amorphous magneto-optic layer
The following table summarizes the -Co-M film composition, the Kerr rotation angle θ, and the increase in θ compared to the case without M.

(Margin below) 9-

[Brief explanation of the drawing]

Figures 1 to 10 are diagrams of changes in θ and He when the amount of M during each magnetic experience in the example is changed. Coo, + )o7q (Tb+
-z Cux)o2+
Crr) o2+

Claims (1)

[Claims] L Tb-Fe having an axis of easy magnetization in the direction perpendicular to the film surface
-Co -M (where M is Sn, B1,
Ni. an amorphous magneto-optical layer consisting of at least 1 m) selected from Cr and Cu;