JPS61104445A - Photomagnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a photomagnetic recording medium for which a thin amorphous magnetic alloy film permitting the change of the coercive force without changing the Kerr rotating angle is used as a recording medium by forming a magnetic alloy having the axis of easy magnetization in the direction perpendicular to the film plane and consisting of a rare earth element, ferrous transition metal and-Ib metal as a recording layer. CONSTITUTION:A high-frequency sputtering device is used for the manufacture of the film and a composite target dispersed and disposed with Tb and Cu or Ag which is the group-Ib element on an Fe plate is used for the target. The compsn. is so adjusted as to attain Tb32Fe68-xXx(X=Cu, Ag) by area ratio of the target. The film compsn. at X=0 is 25at% Tb and Tb rich for the compensation compsn. according to XMA. The sputtering conditions are summed up to the target: Tb32Fe68-xXx(X=Cu, Ag), a substrate: glass, back pressure: <=2X10<-7>Torr, gaseous Ar pressure: 4X10<-2>Torr, sputter power: 3W/cm<2>, inter- electrode distance: 5cm.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a magnetic thin film recording medium used in a magneto-optical disk memory. The present invention relates to a magnetic thin film recording medium in which information can be recorded by creating inverted magnetic domains in a region irradiated with an original beam of a laser or the like, and which can be read out using the 8-magnetic optical effect.

(Prior art and its problems) Original disk memory has attracted attention in recent years as a type of large-capacity file memory because it is capable of high-density, large-capacity recording, and non-contact ψ high-speed access. . Among them, magneto-optical disk memory has the advantage of being able to review recorded information.
It is being actively researched in various places.

Conventionally, MnB1. Amorphous magnetic alloys i8M and G created by combining polycrystalline thin films such as MnCuB1, rare earth metals such as Tb, Gd, and DY, and iron group i-transfer metals such as Fe e Co.
Single crystal films such as IG are known. Among these thin films, amorphous matrix alloy thin films have advantages such as high concentration sensitivity, no grain boundary noise, and easy formation of tears with magnetic anisotropy perpendicular to the film surface. , is considered the most promising as a recording medium.

As is well known, in such a recording medium, there is a relationship as shown in FIG. 3 between the Kerr rotation angle θk, the coercive force HC, and the film composition, which greatly affect the reproduction characteristics. In other words, the Kerr rotation angle θ monotonically decreases as the rare earth concentration increases;
The coercive force Hc becomes large near the compensation composition. Here, in order to obtain a reproduction output with a high 2 ratio, it is preferable that θ is as large as possible, but regarding the coercive force HC, the magnitude and the direction for the compensation composition are determined according to the requirements of the recording and reproduction method.
It is necessary to select as appropriate. Therefore, in the past, depending on the set value of coercive force (c), the Kerr rotation angle θk often became small. For example.

In the case of 'pbpe, it is said that the Tb1J Tsuchi composition is the best for the compensation composition in terms of recording and reproducing characteristics, but in order to reduce characteristic unevenness over a large area, the vicinity of the compensation composition where the change due to the Hc composition is large is It was necessary to select a low Hc region that was avoided and slightly separated from it. In this case, since the Kerr rotation angle θ becomes small, a problem arises in that the reproduction output becomes small.

(Objective of the Invention) The present invention has been made to solve all of the above problems, and provides a recording medium with an amorphous magnetic alloy thin film that can change the coercive force Hct without changing the Kerr rotation angle θk. It is an object of the present invention to provide a magneto-optical recording medium having the following characteristics.

(Structure of the Invention) The magneto-optical recording medium according to the present invention has an axis of easy magnetization in the direction perpendicular to the film surface, and has a recording layer made of a magnetic alloy mainly composed of rare earth elements, iron group transition elements, and group Ib elements. To do t-Characterize.

(Example) Hereinafter, one embodiment of the present invention will be described in detail.

A high frequency sputtering device was used to prepare the film. As a target, a composite target in which Tb and Cu or Ag t'' of group Ib elements were dispersed on a PE plate was used. The composition is the target area ratio 'l'bi2Fess-xX
x (x=cu#Ag). X=O
According to XMA, the film composition at K is '1'b 27 a
t% and was Tb1J with respect to the compensation composition. The sputtering conditions are summarized below for target 7-)
Tb sz Fe @s-1Xx (X=Cut Ag) Substrate Glass Back pressure 2 x 10'' 7 Torr or less Ar gas pressure 4 x 10 TOrr Sputtering power 3 W/d Distance between electrodes 5α Figure 1 shows the first embodiment of the present invention. Showing examples 6t)T
This figure shows the change in the Kerr rotation angle θ and the coercive force 1 (c) when Cu′t− is added as a group Ib element to bFe.The film thickness is 1500A, and all films are The film exhibited Tb-rich characteristics, had an easy axis of magnetization perpendicular to the film surface, and was X-ray amorphous.According to Figure 1, 'l', Cut-3.5% to bFe As it is added, the coercive force HC increases from 3.5KOC to IKOe.
However, there was no change in the Kerr rotation angle θ at all.

FIG. 2 shows a second embodiment of the present invention,
The figure shows the change in coercive force 1 (c) as a function of the Kerr rotation angle θ when Ag is added as an Ib group element to TbFe. In this case as well, the obtained film with a thickness of 1500 A is entirely non-conductive. It is a crystalline perpendicular magnetization film, and Tb1J for the compensation composition.
It showed the characteristics of Tutsi. And TbFe hair Ag t-
As it is added up to 3,596, the coercive force Hc increases to 3.5
Although the value decreased from KOe to 1.5KOej, the Kerr rotation angle θ did not change at all.

Furthermore, even if Ag or Cu was added in an amount exceeding 15.0%, the above effect did not change; however, when the amount was in the range of 10 to 20%, the magnetic properties deteriorated and the material became unsuitable as a magneto-optical recording medium.

The above-mentioned effect of adding group Ib elements to TbFe is not limited to the above-mentioned composition;
A similar effect was observed for all compositions denoted by x (18-X 35 at %). Furthermore, the effect of Au as a group Ib element was also confirmed.

The above effect can also be achieved by other magnetic alloys made of rare earth elements and iron group transition elements, such as TbpeCo and QdTbpe.

Similar results were observed for GdTbFeCo, TbFeNi, and TbFeNiCo.

(Effects of the Invention) As described above, according to the present invention, a magneto-optical recording medium using an amorphous magnetic alloy thin film that can change the coercive force Hc without changing the Kerr rotation angle θk can be used. Can be provided.

Therefore, the present invention can be effectively utilized in media design according to the playback method.

[Brief explanation of drawings]

Figures 1 and 2 show examples of the present invention, and Figure 3 shows
FIG. 2 is a diagram for explaining a conventional example. Multi 1 Figure Cu amount X% Multi 2 l Agt x%

Claims (1)

[Claims] (1) A magneto-optical recording medium characterized by 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, and an Ib group element as main components.