JPS6243847A - Photomagnetic recording medium - Google Patents

Abstract

PURPOSE:To improve photomagnetic characteristics and to easily manufacture an alloy target for sputtering by adding light rare earth metals Sm, Pr, Nd, Ce and further Pt and Bi in addition to heavy rare earth metals Tb, Gd, Dy and transition metals Fe, Co and Ni thereto. CONSTITUTION:A photomagnetic recording medium is formed of >=1 kinds among the light rare earth metals Sm, Nd, Pr, Ce(LR), >=1 kinds among the heavy rare earth metals Tb, Gd, Dy(HR) and >=1 kinds among the transition metals Fe, Ni, Co(TM) and Pt, Bi. x, y, z are specified to 0.1<=x<=0.8, 0.1<=y<=0.5, 0<z<=0.1 when the compsn. formula is (LR1-xHRx)yTM1-y-z(Pt, Bi)z. The characteristics equal to the characteristics of the photomagnetic recording medium which is hereto used are thus obtd. by the compsn. from which the alloy target can be easily manufactured. The replacement of Tb which is slight in resources with ample Nd is also possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magneto-optical recording medium, for example, a recording medium that is rewritable by irradiation with laser light and can be written to and read from.

[Summary of the invention]

The present invention applies the heavy rare earth metals Tb, Gd, Dy, transition metals We, 0, which have been conventionally used in magneto-optical recording media.
0. In addition to Mi, light rare earth metals Sm, Pr, Nd, O
e Furthermore, by adding Pt and Bi, its magneto-optical properties are improved, and furthermore, it is possible to easily produce an alloy target for sputtering.

[Conventional technology]

Conventional magneto-optical recording media include, for example, Japanese Patent Application Laid-Open No. 57-9494.
Heavy rare earth metal Tb, () + 1°Dy as in 8
It consists of an amorphous alloy thin film composed of one or more of Fe and aO.

As is well known, the conditions for obtaining a perpendicularly magnetized film are Ku〉2π
M: It is written as. However, Ku is magnetic anisotropy energy (θrg/匡), and M8 is saturation magnetization (θmu/ω). Heavy rare earth metal-iron alloys and heavy rare earth metal-cobalt alloys produced by sputtering are amorphous;
Like the crystalline alloy, it becomes a 7-edge magnetic material. Therefore, thin films having compositions that have a small residual magnetization and a large coercive force have been used as magneto-optical recording media.

[Problem that the invention seeks to solve]

However, Tb, Gd, which is used as a magneto-optical recording medium,
As is well known, Dy tends to form intermetallic compounds with transition metals near the compensation composition, and simply melting and casting them has the disadvantage of being easily broken, and special techniques are required to produce an alloy target. Therefore, composite targets are used to produce thin films by sputtering.

In the compound target method ■ It is difficult to control the composition of thin films.

■ In order to obtain a thin film with a uniform composition, complicated procedures such as carefully arranging the pellets are required.

It has the following drawback. In particular, the above-mentioned term 0 is a serious defect that must be overcome in order to improve the O/N of the magneto-optical recording medium, since non-uniformity in the thin film composition causes noise during reproduction.

Therefore, the present invention aims to solve these problems.
The purpose is to make it possible to create an alloy target necessary to create a film with a uniform composition, and to replace conventional heavy rare earth metals, especially Tb, which are scarce in terms of resources, with abundant light rare earth metals. The purpose of the present invention is to provide a magneto-optical recording medium that is cheaper and has higher performance than other conventional media.

[Means for solving problems]

The magneto-optical recording medium of the present invention is made of light rare earth metal Sm.

One or more types of Nd, Pr, Os (hereinafter referred to as ILR), and heavy rare earth metals PATb, Ga, ny (hereinafter referred to as HR).
It's called. ) one or more types, and transition metals Fe, Ni, C
(hereinafter referred to as TM), and one or more of Pt and Bi. The composition formula is (LRl-, rHR, r)
When yTMx-y-z (Pt, Bi)Z, in the present invention, 1. r, y, z are 0.1 x x 0.8.0,
1 ri3/ri0.5 T o (z<o, 1.X
More preferably, o, 2<, x<, 0-6°, most preferably Ha0.3<, x<0.5. Moreover, y is more preferably 0.25 <, y <, 0.4,
Most preferably, 0.3<0.4. Also 2
is more preferably 0.02<, z ri o, 1, most preferably 0.03 x 0.0B.

〔Example〕

The effects of the present invention will be described with reference to Examples.

All thin films shown in this example were produced by sputtering. In addition, the composition formula is ((LR)l-x(HR),z:)y (TM)ty
-z (Pt, Bi) For thin films with x<0.8 when expressed as z, use an alloy as a target that is melted and cast in a low frequency melting furnace and then formed to a diameter of 4 inches and a thickness of 4 inches. there was.

Sputtering conditions are initial vacuum level 1X 10-''ro
Below, the argon pressure is 5rIL'rorr, and the substrate pressure is Ov.

Figure 1 shows (N(lo, 4Dyo, 6)o, 31i('
Pe0.7000.3)0.115-z (Pt, Bi
) The composition dependence of the Kerr rotation angle (hereinafter referred to as θ) of Z is shown. The addition of Pt, Bi, and Ti increases the Kerr rotation angle, and the effect of the addition is that of Bi.

It is large in order of Pt. Curie temperature is (NdO,
4Tb0.6 )0.35 (yeo,ycoo,s
) o, s 5 has hardly changed from about 180°C.

Figure 2 shows (LRo, 4Tb0.3Gt10.3)0.
35 (?e0.6000.4)o, as-zBiz
The dependence of the composition on θ is shown. However, LR=Nd, Sm.

Oe, Pr.

Figure 5 shows (Ndo, 4Tbo, s)o, ss (Pe
ty(Ni,0o)y)o,a.

The composition dependence of the Kerr rotation angle of Pto, os is shown. 0
There is a remarkable increase in the Kerr rotation angle due to the addition of 0.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to obtain properties equivalent to those of conventionally used magneto-optical recording media with a composition that allows easy production of an alloy target. Furthermore, since Tb, which is scarce in terms of resources, can be replaced with abundant N(i), it has the effect of avoiding the depletion of materials expected in the future.

[Brief explanation of drawings]

Figure 1 (Nd O, 4Dyo, e door 35 (Feo70
2 dependence diagram of the Kerr rotation angle of 0o,s)o,5s-az(Pt, Bi)2. Figure 2 (LRo4Tbo4Gdo2) o, ss (F
eo, aC! oo4) 2 dependence diagram of Kerr rotation angle of o, as-zBiz. Figure 3 (Nao4Tbo,s)0.35 (yet
-y(Nt,co)y)o,a. The y dependence diagram of the Kerr rotation angle of pto, os. that's all

Claims (1)

[Scope of Claims] One or more of the light rare earth metals Sm, Nd, Pr, and Ce, one or more of the transition metals Fe, Ni, and Co, one or more of the heavy rare earth metals Tb, Gd, and Dy, and P.
The composition formula is {(LR)_1_-_x(HR)_x}_y(TM)_
When expressed as 1_-_y_-_z(Pt, Bi)_z, it is characterized by being in the range of 0.1<x<0.8 0.1≦y≦0.5 0<z<0.1 Magneto-optical recording medium. (However, LR is the above-mentioned light rare earth metal Sm, Pr, Nd,
One or more types of Ce, HR is the above, heavy rare earth metal Tb
, Gd, and Dy. )