JPH01102757A - Magneto-optical recording medium - Google Patents

Abstract

PURPOSE:To improve magnetic characteristics and magneto-optical characteristics by substituting a part of Fe of magnetoplumbite type ferrite with Co and executing the electric charge compensation thereof with F. CONSTITUTION:The magnetoplumbite type ferrite expressed by MeFe12O19 (Me: 1 or >=2 kinds of Sr, Ba and Pb, etc.) is formed as a magnetic layer on a transparent substrate 1 and a part of the magnetoplumbite type ferrite is substd. with Co. The charge compensation thereof is executed with F. The Faraday rotating angle is thereby improved without degrading the coercive force and the magnetic characteristics and magneto-optical characteristics are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a magneto-optical recording medium capable of high-density recording and reproduction using laser light.

[Prior art]

In recent years, magneto-optical recording media have attracted attention, in which information is recorded by writing magnetic domains in a magnetic thin film using the thermal effect of semiconductor laser light, etc., and information is read out using the magneto-optic effect. Currently, GdCo is a magnetic material used in magneto-optical recording media.

Rare earth-transition metal amorphous alloys such as GdFeCo and TbFeCo are being actively researched and are about to reach the commercialization stage. This amorphous magnetic material has no grain boundary noise, and saturation magnetization Ms can be controlled by adjusting the composition. It has the advantage of being easily obtained.

However, since amorphous magnetic materials, particularly transition metal components, are susceptible to oxidative corrosion, they have a major drawback in that their magnetic properties deteriorate over time.

In order to prevent this, it is known to provide a protective layer such as 5in2 or AQN on the amorphous magnetic film by vacuum evaporation or sputtering. Residual oxygen, oxygen adsorbed on the substrate surface,
Oxygen contained in water or alloy magnetic target,
Due to water ° etc.

The magnetic film is oxidized and corroded over time, and this corrosion is further accelerated by the heat during recording. Additionally, amorphous magnetic materials have the problem that they are easily crystallized by heat, which tends to cause deterioration of their magnetic properties.

We believe that magnetoplumbite ferrite, represented by Ba ferrite, can easily obtain a stable perpendicularly magnetized film due to its large magnetic anisotropy, and that it will deteriorate due to oxidation because it is an oxide. Focusing on the fact that there is no risk of this, that is, it has excellent weather resistance,
Considering application to magneto-optical recording media, published Japanese Patent Application Laid-open No. 59-456.
It is proposed as No. 44. Such magnetoplumbite type ferrite is represented by the following general formula, and although it has excellent magnetic properties, it has a Faraday rotation angle of 0.
It is as small as 2deg/ttm (λ=780nm).

MeFe, 201g (Me: one or more of Sr, Ba, pb, etc.) To increase this Faraday rotation angle, part of the Fe is
o, and charge compensation accompanying this Coff1 exchange must be performed on a part of Fe with a tetravalent nonmagnetic cation (Ti, Ge, etc.).

As the amount of substitution increases, the number of nonmagnetic ions increases and the coercive force (He) tends to decrease, and when the amount of Co substitution increases to 0.1-
There was a problem in that the amount was limited to about 0.6 mol, and there was a limit to increasing the Faraday rotation angle.

[Purpose] - The present invention solves the above-mentioned conventional problems and provides a magneto-optical recording medium with improved magnetic properties and magneto-optical properties by taking advantage of the characteristics of magnetoplumbite type ferrite which has excellent weather resistance. The purpose is to

〔composition〕

The above problem is solved by replacing a part of Fe in magnetoplumbite ferrite with Co, as shown in Equation 1, and replacing the charge with F, which is a monovalent negative ion and has an ionic radius that is almost the same as ○. It is achieved by doing. This can be expressed, for example, by the following general formula.

MeC0XFetz-XOzs XF'X"'(I)
(Me: one or more of Sr, Ba, pb, etc., X: 0.01≦X≦2.0) FIG. 1 shows a cross-sectional view of an example of the configuration of a magneto-optical recording medium according to the present invention. It is. In the configuration example shown in FIG. 1, a magnetic layer 2 is provided on a transparent substrate 1, and a reflective layer 3 is provided thereon. Furthermore, this reflective layer 3
It is constructed by laminating a protective layer 4 thereon.

FIG. 2 shows another example of the structure of the present invention, in which a base layer 5 is provided between the transparent substrate 1 and the magnetic layer 2. In addition, a dielectric layer may be provided between the magnetic layer 2 and the reflective layer 3.

The transparent substrate 1 that can be used in the present invention is quartz glass, A
Various glasses such as N glass or GGG, Li9'/9
Rate, AQ203. Various single crystals such as MoO can be used. The magnetic layer 2 is MeCOlFetz-,0
1,-XFX (Me is Sr.

One or more types of Fe such as Ba and pb) are partially replaced with CO, and the charge compensation is performed with F, and the amount of Co substitution or in the range of 0.01 to 2.0 do. The magnetic layer 2 is formed to a film thickness of 0.1 to 1.0 μm by various sputtering methods such as facing target sputtering, ion blating method, vacuum evaporation method, plating method, and other thin film forming methods.
degree, preferably 0.2 to 0.5 μm. reflective layer 3
Examples include Au, AQ, Ag, Pt, Cr,
Nd, Ge, Rh, Cu.

TiN or the like is used, and the film is formed to a thickness of 0.01 to 1 μm by various evaporation methods such as electron beam evaporation or various sputtering methods such as magnetron sputtering. Further, as the protective layer 4, those conventionally used as a protective layer such as Sio, AfiN, etc. can be used as they are. These films are formed by vacuum evaporation, sputtering, or the like. The base layer 5 is preferably made of spinel ferrite such as NiZn ferrite, and is formed to a thickness of 0.1 by a thin film forming method such as a sputtering method such as magnetron sputtering, an ion blasting method, a vapor deposition method, or a plating method.
A film is formed in the range of −1.0 μm.

A specific example is shown below.

NiZn ferrite (composition: Ni,...
Znl, , Fe, 04) was deposited to a thickness of 0.15 μm,
A magnetic film made of BaCoxFe, -xol, -xFx was formed thereon with the value of X varied from 0.1 to 2.0. Next, a protective film of SiO□ was formed with a thickness of 0.1 μm by sputtering to produce a magneto-optical recording medium according to the present invention as shown in FIG. The third graph shows the dependence of He on the Co substitution amount of this magneto-optical recording medium.
It is shown as curve 1 in the figure.

For comparison, BaCoxMxFel was used as the magnetic layer.
, -2xo,, (however, M=Ti, Ge) was used, but a magneto-optical recording medium was prepared in the same manner, and the Co
A graph of the dependency between the amount of substitution and Hc is shown in FIG. In this comparative example, charge compensation by Co substitution was performed with tetravalent Ti (curve 2 in FIG. 3) and Ge (curve tA3).

From FIG. 3, it can be seen that when charge compensation by Co substitution is performed with tetravalent cations, He decreases as the amount of CO substitution increases, whereas as in the present invention, F, which is a monovalent negative ion, It can be seen that the characteristics of those subjected to charge compensation are almost unchanged even with an increase in the amount of Co substitution.

〔effect〕

According to the present invention as described above, in the magnetoplumbite type ferrite, charge compensation accompanying Co substitution is performed with F, so the Faraday rotation angle can be improved without reducing the coercive force, and the magnetic This has the effect that a magneto-optical recording medium having excellent properties and magneto-optical properties can be obtained.

[Brief explanation of the drawing]

FIGS. 1 and 2 are explanatory views of the cross-sectional structure of a magneto-optical recording medium according to an embodiment of the present invention. FIG. 3 is a diagram showing the relationship between Co substitution amount and retention force in specific examples of the present invention and comparative examples. 1... Transparent substrate 2... Magnetic layer 3...
Reflective layer 4...Protective layer 5...Underlayer

Claims (1)

[Claims] 1. In a magneto-optical recording medium in which a magnetoplumbite type ferrite represented by the general formula: MeFe_1_2O_1_3 (Me: one or more types of Sr, Ba, Pb, etc.) is formed as a magnetic layer, Fe of the magnetoplumbite type ferrite is 1. A magneto-optical recording medium characterized in that a portion of the medium is replaced with Co and charge compensation is performed with F.