JPS61144743A - Optomagnetic recording medium and its production - Google Patents

Abstract

PURPOSE:To obtain a recording layer consisting of an amorphous magnetic alloy having excellent weatherability by forming the recording layer of the magnetic alloy having the axis of easy magnetization in the direction perpendicular to the film plane and contg. a rare earth element, ferrous transition element and nitrogen. CONSTITUTION:The magnetic alloy having the axis of easy magnetization in the direction perpendicular to the film plane and contg. the rare earth element, ferrous transition element and nitrogen is used for the recording layer. The thin film thereof is formed by a high-frequency sputtering device. For example, a composite target dispersed and disposed with Tb chips on an Fe plate is used for the target and a gaseous mixture composed of pure argon and argon nitrogen is used for an atmosphere gas. A vertically magnetizable film having the axis of easy magnetization in the direction perpendicular to the film plane is used when the content of N2 is <=50mol%. The recording layer which has excellent weatherability and is resistant to oxidation and corrosion is thus obtd.

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, and more specifically, it has an axis of easy magnetization perpendicular to the film surface and is suitable for lasers, etc. This invention relates to a magnetic thin film recording medium in which information can be recorded by creating an anti-ri J73 area in an area irradiated with a light beam, and which can be read out using the magneto-optic effect.

(Prior art and its problems) Optical 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, high-speed access.

Among these, magneto-optical disk memories are being actively researched in various places because they have the advantage that recorded information can be rewritten.

Conventionally, MnB1 and MnCu have been used as recording media.
Polycrystalline thin films such as B1, amorphous magnetic alloy thin films created by combining rare earth metals such as Tb, Gd, and B7 with iron group transition metals such as Fe and Go, single crystal thin films such as GIG, etc. Are known.

Among these thin films, amorphous magnetic alloy thin films have high writing sensitivity, can stably create magnetic anisotropy perpendicular to the film surface over a large area, and are amorphous, so grain boundary noise is small and 8/
It is considered to be the most promising recording medium because it has advantages such as being able to read with a good N ratio.

However, this amorphous magnetic alloy thin film has the disadvantage that it has poor weather resistance and is susceptible to oxidation and corrosion. This has caused extremely inconvenient problems in terms of reliability, such as the symbol state changing over time and recording and reproduction becoming impossible depending on the usage environment.

(Objective of the Invention) The present invention was made to solve the above problems, and provides a magneto-optical recording medium using an amorphous magnetic alloy thin film with excellent weather resistance as a recording medium, and a method for manufacturing the same. It is in.

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

In addition, in the method for manufacturing a magneto-optical recording medium according to the present invention, a target containing a rare earth element and an iron group transition element as main components, and an Ntf-P15 gas as an atmospheric gas.
It is characterized in that it is produced by sputtering using a mixed gas of 1% or less of molybdenum and N.

(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 tani-get with Tb chips dispersed on an Fe plate was used, and the film composition was changed to TbxFel by changing the number of Tb chips and the area ratio of the target. . The atmospheric gas used was pure argon and a mixed gas of argon and nitrogen.

The sputtering conditions are summarized below.

Target TbxFel.・-8 board
Glass back pressure 2XI Q-7 mm or less Atmospheric gas pressure 2X 10J Torr Sputtering power
2 shows the relationship between He and the target composition obtained from the Kerr hysteresis curve of a film with a thickness of 1500, which was manufactured by setting the distance between lll15cW and lll15cWL. According to this, as the amount of N in the atmospheric gas increases, the compensation composition shifts to the Tb-rich side, and Hc becomes smaller overall. When the amount of N in the atmospheric gas was 5 molti or less, a perpendicularly magnetized film having an easy axis of magnetization in the direction perpendicular to the film surface was obtained in the vicinity of the compensation composition. N!
No perpendicularly magnetized film was obtained when the amount was greater than 5 mol.

Here, in order to investigate the effects of N and t in the atmospheric gas, the target composition (surface area ratio) Tbst, yF'e
For sy, s, Ntjl A made with O% and target composition Tbl*JF'ese, for y, Nt
Film B prepared using ts* was selected and subjected to an environmental resistance test under the conditions of 60° C. and 80 g6. FIG. 2 shows the change over time of the Kerr hysteresis curve. At the start, each of these films had a Curhiss and Telisis curve with a squareness ratio of 1, and the compensation composition was Tb-rich for humans and Fe-rich for B. According to this figure, 1
After 25 hours, the human body became Tb IJ Petucci and Fe-rich, and the vertical anisotropy also disappeared. On the other hand, even after 245 hours had elapsed in B, although the value of θ decreased considerably, the squareness and directionality of the Kerr hysteresis curve were maintained.

In addition, the target composition was changed to -Tb31. In the case of yFe/Te, the change over time of the film prepared with 2 mol of Nt was smaller than that of the film prepared with MaIIkO.

The above results were obtained under conditions containing horse as an atmospheric gas.
The fabricated membranes show improved weather resistance.

(Effects of the Invention) In the above embodiments, the effects of N and inclusion in the atmospheric gas were described with respect to TbFe1, but magnetic alloys made of other rare earths and iron group transition metals, such as TbFeCo,
GdTbFe, 0dTbFeCo, 'l
'bJi'eNi.

A similar effect can be obtained by using TbFeCoN.

As described above, according to the present invention, it is possible to provide a magneto-optical recording medium whose recording layer is an amorphous magnetic alloy thin film with excellent weather resistance.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between the amount of N in the atmosphere gas and the relationship between He and the composition of the magneto-optical recording medium according to the present invention. It is a figure which shows the relationship of NtFfL in the inside. Forest cutter Susumu Uchihara 6゛H6 (KOe)

Claims (2)

[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, and N. (2) The target is mainly composed of Tb and iron group transition elements, and the atmospheric gas has a N_2 content of 5 mol.
1. A method for producing a magneto-optical recording medium, the method comprising producing a magneto-optical recording medium by sputtering using a mixed gas of Ar and N_2.