JPH01224960A - Magneto-optical recording medium - Google Patents

Abstract

PURPOSE:To enhance corrosion resistance and long period reliability by having an easy axis in an orthogonal direction to a film surface and composing a recording layer of a magnetic alloy containing a rare earth, iron group transition elements, Ta and Ti. CONSTITUTION:On a glass substrate 1, an intermediate layer (a silicon nitride film by means of spatterning) 2, a magneto-optical recording layer (TbFeCo+M by means of the spatterning) 3, and a protective layer (the silicon nitride film by means of the spatterning) 4 are successively formed. Here, M indicates the metallic elements of the Ti and Ta. That is, the both Ti which is the most effective for pitting and the Ta which is the most effective for the corrosion of an external peripheral edge part are simultaneously added to the TbFeCo. Thus, the recording medium having the excellent corrosion resistance can be obtained, and the long period reliability can be enhanced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is used for rewritable magneto-optical disks, etc., and can be read using magneto-optical effects such as the magnetic Kerr rotation effect or the Noah 2-Day effect. The present invention relates to a magneto-optical recording medium capable of recording.

[Conventional technology]

Conventionally, magneto-optical recording media that record information thermomagnetically and reproduce it magneto-optically have a protective layer made of dielectric material on a transparent resin substrate or glass substrate.

Various combinations of a perpendicularly magnetized recording layer, a reflective layer made of a metal film, etc. are formed by a soot method or a vapor deposition method. Among these, GdT is used as a perpendicular magnetization film.
bFe, DyFe, GdCo, TbCo.

Amorphous alloy thin films of rare earth-iron transition metals such as TbDyFe and TbFeCo are considered promising because they are suitable for mass production and have low readout noise.

The intermediate layer between the substrate and the recording layer is formed for the purpose of both preventing oxidation of the perpendicularly magnetized film that is the recording layer and achieving the Kerr/Has effect. Nitride such as N, SiN, etc.

In addition to oxides such as S io and S ioz, ZnS
, MgFz.

Various dielectrics have been used, such as SiC.

[Problem to be solved by the invention]

Perpendicularly magnetized films used in recording layers often lose their perpendicular magnetic anisotropy due to oxidation. In particular, in the case of a rare earth-iron transition metal based perpendicularly magnetized film, since the rare earth metal is easily oxidized, its perpendicular magnetic anisotropy deteriorates even if it is left in the air for several days.

In order to prevent this oxidation, the recording layer is sandwiched between protective layers made of dielectric material, and this has been effective. However, it is difficult to completely prevent oxidation of the recording layer caused by defects such as pinholes, scratches on the substrate, and dust present in the protective layer. Therefore, it is necessary to improve the corrosion resistance of the recording layer itself.

In order to improve the corrosion resistance of the recording layer, non-magnetic elements are added to rare earth-iron transition metal alloys.

The additive element is lf2゜Ti, which is a passive state forming element.
, Cr, and noble metal elements Au, Ag', P
t, etc., but it is not possible to obtain sufficient long-term reliability with only one type of element.

An object of the present invention is to improve the corrosion resistance of a magnetic recording layer and to provide a magneto-optical recording medium with excellent long-term reliability and whose characteristics do not deteriorate even after a long period of time.

[Means for Solving the Problems] The magneto-optical recording medium of the present invention has an axis of easy magnetization in a direction perpendicular to the film surface, and contains a rare earth element, a ferrous transition element, Ta, Ti? Contains magnetic alloy? It is configured as a recording layer.

[Effect]

By adding two types of passivity-forming elements, Ta and Ti, to an amorphous rare earth-iron transition metal alloy thin film, corrosion resistance can be greatly improved without reducing the Kerr rotation angle. I found it.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

Is Figure 1 an embodiment of the present invention? FIG.

On a glass substrate 1, an intermediate layer (a sputtered silicon nitride film) 2 with a thickness of 80 nm, a magneto-optical recording layer (sputtered TbFeCo+M) 3 with a thickness of 80 nm, and a protective layer (a sputtered silicon nitride film) are formed. 4 for 80nrn
Formed sequentially to a thickness of . Here 1M is PL, Ti, C
It represents at least one of the four types of elements: r and Ta.

A sample with the above configuration was immersed in 80C hot water for two days, and the density of pitting corrosion occurring on the medium surface and the number of corrosion occurring from the outer peripheral edge of the sample were compared.

FIG. 2 is a correlation diagram showing the relationship between the type of additive element and the density of pitting corrosion.

The density of pitting corrosion varies by more than two orders of magnitude depending on the type of added element.
Ti, Cr, Ta, and no Pt addition are in descending order.

FIG. 3 is a correlation diagram showing the relationship between the types of additive elements and the number of corrosions from the outer peripheral edge.

The number of corrosion decreases in the order of Ta, Cr, Ti, Pt, and no addition. It is noteworthy that by adding Ta, corrosion from the outer peripheral edge can be completely prevented.

Addition of the fourth element improves weather resistance for all elements. Addition of one type of element was unable to prevent both pitting corrosion and corrosion of the outer peripheral edge. Therefore, Tb
A similar experiment was conducted by adding FeCo1C. As a result, both pitting corrosion and corrosion on the outer edge? At the same time, it could be prevented.

The above effect can be achieved by using magnetic alloys 9 made of other rare earth elements and iron group transition elements, such as GdTbFe and GdTbFeCo.

A similar phenomenon was observed for DyTbFe and the like.

〔Effect of the invention〕

As explained above, since the present invention uses a recording layer with excellent corrosion resistance, it has the effect of improving long-term reliability compared to conventional magneto-optical recording media.

[Brief explanation of the drawing]

FIG. 1' is a sectional view showing one embodiment of the present invention, and FIG. 2 is a correlation diagram showing the relationship between additive elements and pitting corrosion density. FIG. 3 is a correlation diagram showing the relationship between the l additive element and the number of corrosions from the outer peripheral edge. 1...Glass substrate, 2...Intermediate layer, 3
...... Magneto-optical recording layer, 4... Protective layer. Agent Patent Attorney Susumu Uchihara M 1 Figure Pt '7゜C and ;~λ 艷7J[]i 花犀Z Concave

Claims (1)

[Claims] 1. A magneto-optical recording medium having an axis of easy magnetization perpendicular to the film surface and having a recording layer made of a magnetic alloy containing a rare earth element, an iron group transition element, Ta, and Ti.