JPS61165847A - Photomagnetic recording medium - Google Patents

Abstract

PURPOSE:To make possible the manufacture of an alloy target necessary for manufacturing a film having a uniform compsn. by constituting the target of respectively >=1 kinds among light rare earth metals Sm, Nd, Pr, Ce and heavy rare earth metals Tb, Gd, Dy as well as transition metals Fe, Co, Ni. CONSTITUTION:This photomagnetic recording medium consists of >=1 kinds among the light rare earth metals Sm, Nd, Pr, Ce, >=1 kinds among the transition metals Fe, Ni, Co and >=1 kinds among the heavy rare earth metals Tb, Gd, Dy and is limited by 0<x<=0.5, 0.1<=y<=0.4 when the compsn. formula is expressed by {(Sm, Nd, Pr, Ce)1-x(Tb, Gd, Dy)x}y(Fe, Co, Ni)1-y. The alloy target can be easily manufactured of such compsn. and the characteristics equal to the characteristics of the photomagnetic recording medium used heretofore are obtainable. The Tb which is costly owing to the scarecity of resources can be replaced with the amply available hence inexpensive Nd and therefore htis recording medium is manufacturable without the run-out of the material which may arise in future if the use of Tb is continued.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a magneto-optical recording medium, which is a thin film made on a base layer of glass or plastic by sputtering etc. It has anisotropy and can record information by creating reversed magnetic domains by heating with a laser or other device.

The present invention relates to a magneto-optical recording medium in which recorded reversed magnetic domains can be read out by rotating the plane of polarization of reflected or transmitted laser light using the Kerr effect or Faraday effect.

[Conventional technology]

Conventional magneto-optical recording media include, for example, Japanese Patent Application Laid-Open No. 57-9494.
8.L consists of a non-destructive thin film composed of one or more of the heavy rare earth metals Tb, Gd, and Dy and one or more of Fe or 00.

The conditions for obtaining perpendicular magnetization are the well-known LuniKu run 2.
It is written as π. However, Ku is the magnetic anisotropy energy (erg/c+++).The heavy rare earth metal-cobalt alloy produced by sputtering is amorphous. Similarly, because it becomes a ferrimagnetic material, thin films with a composition close to the compensation composition, which has a small residual magnetization and the highest coercive force, have been used as magneto-optical recording media.

[Problems that the invention attempts to solve]

However, Tb is used as a magneto-optical recording medium.

Gd and Dy have the drawback that they are easily broken if the transition metal and intermetallic compound are created in the vicinity of the compensation composition using the known method, and then they are simply melted and cast, and special technology is required to create the alloy target. It is. Therefore, composite targets are used to fabricate thin films by sputtering. In the composite target method, ■ It is difficult to control the composition of the thin film.

■ In order to obtain 4111 with a uniform composition, complicated procedures such as adjusting the arrangement of pellets are required.
′. In particular, the above-mentioned 0 term is a serious defect that must be overcome in order to improve the O/N of the magneto-optical recording medium, since the non-uniformity of the four-olfactory composition causes noise during reproduction.

Therefore, the present invention aims to solve this difficult problem.
The purpose is to make it possible to create the alloy target necessary to create a film with a uniform composition, and to replace the heavy rare earth metals, which are scarce in terms of resources, with the abundant light rare earth metals, compared to conventional ones. The objective is to provide an inexpensive and high-performance magneto-optical recording medium.

[Means for solving problems]

The magneto-optical recording medium of the present invention is made of light rare earth alloy [8m.

Nd, Pr, Oe (hereinafter referred to as %LFI), heavy rare earth metals Tb, Gd, Dy (hereinafter referred to as BR) and transition metals IPe, Co, Ni (hereinafter referred to as TM).
) each consists of -fa@ or more. The composition formula is (LRI
-X HRx ) 7 T M I -y In the present invention, 17 is 0 (x≦(L5゜(Ll≦y≦cL
It is 4. More preferably, X satisfies α2≦X<α5, most preferably 155≦X≦15. Also, y#i is preferably rl, 2≦y≦14, most preferably Fia, zo≦
y(L155.

〔Example〕

The effects of the present invention will be described in Examples.

All the thin films shown in this actual winding example were produced by sputtering. Sputtering conditions are initial vacuum level 5XlO'''
TOrr or less, argon pressure 5 mTorr, +substrate bias voltage Ov.

FIG. 1 shows the composition dependence of the Kerr rotation angle (hereinafter referred to as θ) of (Nd, -xDyx)yFe, -7. The Kerr rotation angle is fixed at tf depending on the composition of θ, and remains unchanged at about 18 minutes even if the dragon of Dy is changed. This value is comparable to that of conventionally used Tb and Fe.

In Figure 2, (N d+-XD7X )o, tm l'el
ljl (N (11-xOdX)a, nF15e,
y* + (N (1+ −XT ”X )a, *F
'96. Nd of coercive force (hereinafter referred to as Hc) of TI
The dependence of K on the amount of heavy rare earth metal substitution is shown. Most Ec
Tb has a large effect of increasing . At L5, which is determined from the first factor and FIG. 2, ak does not decrease due to the composition in which Hc becomes maximum.

Ha is closely related to the stability IC of the recorded bits, and 6 is closely related to the read characteristics of the recorded bits. Therefore, being able to increase lc (by RFI replacement) without lowering ak is advantageous in obtaining stable recording bits.

As shown in Figure 1, W and ak are comparable to the conventionally used Tt) and Fe. In order to further improve θ, an example in which Fe f Co and Ni were substituted - (
N (io, a T 1) oa ) o, ta (Fe6
,1. -ycOyNi6. , ) Fe at θ of o, tl
Figure 5 shows the dependence of CO on the amount of CO substitution. y= for θ
When it is 15, the maximum value is 22 minutes. It was possible to raise the ak to the same level as GdFe, which is known to have a high ak. Note that no change in Ha was observed due to substitution with F+5t-Ni, Co. Records of known sea urchins
Since the C/N during reproduction is proportional to /TTT when R is the reflectance, it is L for improving θ.

C/N during playback has improved.

Ndt in Figure 4? ((Ndt-X LRx)6,11 IJ substituted with light rare earth metals such as Sm, Co, and Pr
71L4)6. tl"elL?B shows 0k. (However, LR=Sm, Oe, Pr.) 8m substitution shows the greatest improvement in Eri θ, followed by C1 and Pr. Both are ak is maximum when X=105.

〔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 base metal targets and substrates. Furthermore, try
7ThTb, which is expensive due to its scarcity, and Nd, which is inexpensive due to its abundance.
Because it can also be replaced with .

If Tt) is continued to be used, it has the effect of avoiding material depletion that may occur in the future.

[Brief explanation of drawings]

Figure 1 (Nd+ -2CD7X)o, ts Flil(
L? The figure which shows the XX existence of the Kerr rotation angle of I. Figure 2 ("+ -"D7") o, ts Fea, n+
(N"+ -xG") o, ts "a, ta + (
N (11-xTbX). , 1a F e(1,7
1 is a diagram showing the X dependence of coercive force of No. 1. Figure 5 (Ndo, a T bo, *) n, ta (F
ee, o-yC! A diagram showing the y dependence of the Kerr rotation angle of gyN t (1, 1) o, ys. SatoA 1';4 ((Nd, -xLRx)6.6 I
J7o41. , , The diagram showing the y dependence of the Kerr rotation angle of Fe, , (LR = 8m, Pr, Oe)

Claims (1)

[Scope of Claims] Consists of 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, and one or more of the heavy rare earth metals Tb, Gd, and Dy. , the composition formula is {(Sm, Nd, Pr, Ce)_1_-_x(Tb, G
d, Dy)_x}_y(Fe, Co, Ni)_1_-_
A magneto-optical recording medium characterized in that, when expressed as y, the following conditions apply: 0<x≦0.5, 0.1≦y≦0.4.