JPS60130806A - Amorphous magnetooptical layer - Google Patents

Abstract

PURPOSE:To obtain an amorphous magnetooptical layer having the large Kerr rotation angle thetak, and moreover having large coercive force Hc by a method wherein copper or chromium of the specified quantity is contained in a Dy-Fe film having the direction of easy magnetization in the direction perpendicular to the film surface. CONSTITUTION:A Dy-Fe-Cu film or a Dy-Fe-Cr film containing Cu or Cr of at least 0.5atom% is formed according to the sputtering method, etc. on a non-magnetic substance consisting of glass, plastics, ceramics, etc. A Dy chip and a Cu or Cr chip are put on an Fe disk to construct a target using the composite method, for example, and composition is controlled according to the ratio of the surface area of the target. Because sufficient Kerr rotation angle can not be obtained when content of Cu or Cr is less than 0.5atom%, while coercive force Hc and the Kerr rotation angle thetak become small when content is enlarged too much, the range of 0.5-5atom% is desirable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an amorphous magneto-optic layer used in a magneto-optical recording medium.

[Prior art]

Conventionally, polycrystalline metal thin films such as MnB1 and G
Amorphous metal thin films of a-00% Gd-Fe and compound single crystal thin films typified by GIG are known. Although these thin films have various advantages, MnB1 has the disadvantage that it is technically difficult to fabricate thin films due to its high Curie point, and that it requires a large amount of energy to write when used in magneto-optical disks. . Also, Gd-Co
The amorphous metal thin film of Gd-Fe has the disadvantage that the coercive force at room temperature is small (300 to 5000 e) and recorded information is unstable.

Therefore, as a new magnetic thin film recording medium that eliminates the drawbacks of the conventional magnetic thin film recording media as described above, an amorphous Dy-Fe material having an axis of easy magnetization perpendicular to the film surface and containing 18 to 28 atoms of B7 has been developed. A magneto-optical storage medium comprising a alloy film has been proposed (see Japanese Patent Publication No. 57-20692). However, the above-mentioned alloy film has a problem in that although the Curie temperature Tc is low at around 70° C., the Kerr rotation angle θk is small at around 0.15 degrees, making it impossible to obtain a sufficient reproduction output.

〔the purpose〕

The present invention has been made in view of the above-mentioned current situation, and its purpose is to provide an amorphous magneto-optic Iv1 having a large Kerr rotation angle θk and a large coercive force Ha.

〔composition〕

The amorphous magneto-optical layer of the present invention contains at least 0.5 atoms of copper or chromium in a Dy--Fe film having an axis of easy magnetization perpendicular to the film surface.

In the present invention, the content of copper and chromium is limited to at least 0.5 atomic atoms each in order to obtain a large Kerr rotation angle, whereas if it is less than 0.5 atomic atoms, a sufficient Kerr rotation angle cannot be obtained. The effects of the present invention are not achieved. On the other hand, if the content of copper and chromium is too large, the coercive force Ha becomes small and the Kerr rotation angle θ also becomes small, so a range of 0.5 to 5 atoms each is preferable.

The magneto-optic layer of the present invention is formed by sputtering, vapor deposition, ion blating, etc. on a non-magnetic substrate made of glass, plastic, ceramic, etc. It can be produced by forming a Dy-Fe-Or film containing at least 0.5 atoms of Or. Preferably, the film is formed by sputtering. The target is, for example, a composite method, with K Dy and O
A groove is formed by placing a U chip or an Or chip, and the composition is controlled by the area ratio of the target surface.

Further, when the magneto-optic layer of the present invention is used in a magneto-optical recording medium, it may be used alone or together with a film or other film. For example, a protective film such as 5102.5i
A film made of O1Si3N4 or the like can be provided on or below the Dy-Fe-0u film or the Dy-Fe-0r film by sputtering, vapor deposition, ion blating, or the like.

〔Example〕

The present invention will be specifically explained with reference to Examples below.
It is not limited to this.

Example 1 In this example, a Dy-Fe-0u film with a thickness of about 2000λ was deposited on a slide glass substrate under the following sputtering conditions.
F by replacing a part of D7 of the y-Fe film with O.
It was produced by changing X in e0.78 (Dy1-XOux)0.22. In addition, in the case of Dy-Fe film, 18-2
When Dy is 8 atoms, perpendicular magnetic anisotropy is exhibited, and the compensation composition is around Dy of about 22 atoms.

Sputtering conditions> Residual gas pressure Near x 10 TOrr Ar gas pressure: 2 x 10 'rorr Discharge power:
400W Press sputtering time: 60 minutes Main sputtering time: 10 minutes The recording medium produced as described above was irradiated with an Hθ-Me laser (λ = 655 nm) from the substrate side to change the Kerr rotation angle θ and coercivity due to the Kerr effect. I met Hc. As a result, the changes in Kerr rotation angle θ and coercive force Hc with respect to the addition amount of 0 u were as shown in FIG. It can be seen from this figure that as the amount of O added increases, Hc decreases, but θ increases.

In this example, D7 was replaced with 0u, so when Ou was increased, D7, which contributes to anisotropy, decreased and Ha suddenly decreased, so it was not possible to increase the amount of Ou added by 711. If O is added while keeping the ratio of Dy and Fe constant, a rapid decrease in Ha can be prevented and the amount of O added can be increased. When we actually compared θ, ? "When 0.78D70..22, -0.15de to θ
gFeo, 7s (D7o, 960uo, o4) o, 22
When θ=0.22 deg, it is clear that θk increases by 47 degrees by adding cu.

Example 2 In this example, a Dy-Fe-Or film with a thickness of about 2000λ was deposited on a slide glass substrate under the following sputtering conditions.
It was produced by changing X in 78C1,78(D71-xcrx)0-22 by replacing a part of Dy in the Dy-Fe film with Or. In addition, in the case of Dy7Pe film, 18
When Dy is ~28 atoms, it exhibits perpendicular magnetic anisotropy, and the compensation composition is around D7, which is about 22 atoms.

<Sputtering conditions> Residual gas pressure: 7 x 10-'Torr Ar gas pressure: 2 x 10 Torr Discharge power + 400W Press Norita time: 6s minutes 1' for main sputtering! 1: The recording medium produced as described above was irradiated with a He-Ne laser (λ=636 tun·) from the substrate side for 1 s to set the Kerr rotation angle θ and the coercive force Hc due to the Kerr effect.

As a result, the changes in Kerr rotation angle θ and coercive force Hc with respect to the amount of Or added were as shown in FIG. 2. From this figure, O
It can be seen that as the amount of r added increases, Ha decreases, but θ increases.

In this example, D7 was replaced with Or, so if Or was increased, Dy, which contributes to anisotropy, would decrease and Ha would rapidly decrease, so the amount of Or added could not be increased to 1. By adding Or while keeping the ratio of D7 and Fe constant, a rapid decrease in Ha can be prevented and the amount of Or added can be increased. When actually comparing θ, when Fen, 78D70.22, θ was ±0.15deg.
F'80.78 (D70.94Or0.06)0.22
When θ was -0.18 deq, it was clear that θk increased by 20% by adding Or.

〔effect〕

The amorphous magneto-optic layer of the present invention can provide a magneto-optical recording medium with a large Kerr rotation angle θ and a large coercive force Ha.

[Brief explanation of drawings]

FIGS. 1 and 2 are diagrams showing the relationship between Kerr rotation angle and coercive force with respect to changes in composition in determining the optimum conditions for the magneto-optic layer of the present invention. Patent applicant Rico Co., Ltd. - Fig. 1 Fe0.78 CDy+-x C(Lx)o, Fig. 2 of 22

Claims (1)

[Claims] An amorphous magneto-optical layer comprising at least 0.5 atoms of copper or chromium in a Dr-Fe film having an axis of easy magnetization perpendicular to the film surface.