JPS61104446A - Photomagnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a photo magnetic recording medium for which a thin amorphous magnetic alloy film having a large 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 contg. a rare earth element, ferrous transition metal, Ag and N 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 chips and Ag chips on an Fe plate is used for the target. The compsn. is adjusted to attain Tb36Fe64-xAgx by area ratio to the target and pure argon and a gaseous mixture composed of argon and nitrogen is used as the gaseous atmosphere. The compsn. of the film manufactured in the pure argon atmosphere with the target compsn. of x=0 is 30at% Tb and Tb rich with respect to the compensation compsn. according to XMA. The sputtering conditions are summed up to the target: Tb36Fe64-xAgx, a substrate: glass, back pressure: <=2X10<-7>Torr, gaseous atmosphere pressure: 2X10<-2>Torr, sputtering power: 2W/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 magneto-optical disk memories, and more specifically, it has an axis of easy magnetization perpendicular to the film surface and This invention relates to a magnetic thin film recording medium in which information can be recorded and read by making use of the magneto-optical effect by completely creating inverted magnetic domains in the area irradiated with the original beam.

(Prior art and its problems) Optical disk memory is capable of high-density and large-capacity recording;
In addition, contactless and high-speed access is possible.
It has attracted attention in recent years as a type of large-capacity file memory. Among these, magneto-optical disk memories have the advantage that recorded information can be rewritten, and are therefore being actively researched in various places.

Conventionally, MnB1. Polycrystalline thin films such as MnCuB1, amorphous magnetic alloy thin films created by combining rare earth gold layers such as Tb, Gd, l)y, and iron group transition metals such as Fee Co, and single crystal thin films such as GIG. etc. are known. Among these thin films, amorphous magnetic alloy thin films have advantages such as high writing sensitivity, no grain boundary noise, and easy production of films with matrix anisotropy perpendicular to the film surface. , is considered the most promising as a recording medium.

However, since this film generally has a small Kerr rotation angle, it has the disadvantage that the reproduction rate of a magneto-optical disk memory using this film as a recording layer cannot be very high. In order to improve the performance of magneto-optical disk memories, it is necessary to increase the Kerr rotation angle θ of the film as much as possible. For this reason, many studies are being conducted to increase the Kerr rotation angle θk by adding various elements to the film.

(Objective of the Invention) The present invention has been made from this point of view, and it is an object of the present invention to provide a complete magneto-optical recording medium whose recording layer is an amorphous magnetic alloy thin film having a large Kerr rotation angle θ.

(Structure of the Invention) The magneto-optical recording medium according to the present invention has an easy axis of magnetization in the direction perpendicular to the film surface, and contains a rare earth element, an iron group transition element, Ag and N.
It is characterized in that the entire recording layer is made of a magnetic alloy containing i.

(Example) Examples of the present invention will be described in detail below.

A high frequency sputtering device was used to prepare the film. As a target, a composite target rattler on which Tb chips and Ag chips were dispersed was used on a PE board.

The composition is the area ratio of the target, TbxsFes<XA
It was prepared so that g x. Also, as an atmospheric gas,
Pure argon and a mixed gas of argon and nitrogen were used. x
According to XMA, the composition of the film produced in a pure argon atmosphere with a target composition of =Q was Tb3Qat%, which was Tb1J with respect to the compensation composition. All sputtering conditions are shown below.

Target Tb 5gFe s4-) (Agx group
Plate glass back pressure 2 x 10 Torr or less Atmospheric gas pressure 2 x 10 'f'orr Sputtering power 2W/7 Interelectrode distance 5α Figure 1 shows that the car The relationship between the Kerr rotation angle θk and the coercive force HC obtained from the hysteresis curve and the target composition is shown using Nxi: in the atmospheric gas as a parameter. All of the films exhibited Tb1J characteristics with respect to the compensation composition, had easy magnetization axes perpendicular to the film plane, and were X-ray amorphous.

According to the HX1 diagram, in the case of pure argon atmosphere, TbFe
As the amount of Ag added increases, the coercive force HC monotonically decreases, but the Kerr rotation angle θ hardly changes.

On the other hand, in a film fabricated in a mixed gas atmosphere of Nz 412M, the compensation composition of the film shifts to the Tb glitch side, and the coercive force H
c increased overall. And the Kerr rotation angle θ is
Although there was almost no change in the target composition, it was about 9 times larger than that produced in a pure argon atmosphere. Similar trends were observed when the amount of N2 in the atmospheric gas was 3 to 4 molt, but N! A perpendicularly magnetized film could not be obtained when the amount was 5 molti or more.

The effect of adding Ag and N to 'pbpe as described above is not limited to the above-mentioned composition;
oo-d −x Ag X Q8≦y≦35at%, 0
Similar effects were observed for all compositions shown in 5). However, in the range of 10<x<20, the characteristics deteriorate, making it unsuitable as a magneto-optical recording medium.

The above effect can be obtained by using magnetic alloys made of other rare earth elements and iron group transition elements, such as TbFeCo, GctTbFe, and GdTbF.
Similar results can be seen for eCo, TbPeNi, and TbFeNiCo K.

(Effects of the Invention) As described above, according to the present invention, it is possible to provide an entire magneto-optical recording medium having an amorphous magnetic alloy thin Me recording layer with an increased Kerr rotation angle θ.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

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, Ag, and N.