JPH0536134A - Magneto-optical recording medium - Google Patents

Abstract

PURPOSE:To make reproducing signal of a magneto-optical disk made from MnBi compound as a recording material large and to enhance repeating stability of recording and reproducing characteristics. CONSTITUTION:The recording material is MnBi-X (where X expresses at least one kind of B and C). B and C, which is small in ion diameter, enter into a position between lattice of MnBi to suppress structural phase change of MnBi from low temp. phase to high temp. phase. In this result, thermomagnetic recording is executed without remaining high temp. phase of metastable state in the room temp.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical recording medium,
More specifically, the present invention relates to a magneto-optical recording medium which is used in a rewritable magneto-optical disk or the like and which can be read using a magneto-optical effect such as a magnetic Kerr effect or a magnetic Faraday effect.

[0002]

2. Description of the Related Art The following conditions are mainly required as materials for magneto-optical recording media. (A) A perpendicular magnetization film. (B) It has a large coercive force. (C) The car rotation angle is large. It is known that when a heavy rare earth element such as Tb or Gd is added to Fe or Co or the like, the magnetic anisotropy increases and a perpendicular magnetization film is formed. For these reasons, GdTbFe, DyFe, GdCo, TbCo, Tb are used as materials for the magneto-optical recording medium.
A heavy rare earth-3d transition metal amorphous alloy thin film such as DyFe or TbFeCo satisfies the above conditions and is suitable for mass production,
Promising because there is no read noise. TbFeCo is particularly promising and has become a practical material.

On the other hand, using a short-wavelength laser as a means for increasing the density of magneto-optical recording to reduce the recording area has been studied. However, since the Kerr rotation angle of the heavy rare earth-3d transition metal amorphous alloy thin film becomes smaller as the wavelength becomes shorter, the reproduction output decreases when reproduced by a short wavelength laser. Therefore, a new magneto-optical recording material for short wavelength is needed. The MnBi compound is Bi on the substrate.
When the Mn-Bi laminated film in which Mn and Mn are sequentially formed is heated and reacted, the C-axis orientation of Bi is preserved and the M-axis of M of C-axis orientation is preserved.
It becomes an nBi compound. Since the MnBi compound has a strong magnetic anisotropy in the C axis, it becomes a perpendicular magnetization film. Also, Mn
Since the Bi compound has a large Kerr rotation angle even in the short wavelength region, it is promising as a magneto-optical recording material for short wavelength. In order to heat and react the Mn-Bi laminated film in which Bi and Mn are sequentially formed on the substrate, it is necessary to hold the laminated film in an atmosphere at a temperature of 300 ° C. or higher. The reaction is carried out in a vacuum electric furnace.

[0004]

[Problems to be Solved by the Invention] However, MnB
There are the following problems in using the i compound as a magneto-optical recording material. The principle of recording on a magneto-optical recording medium is that the magnetization of the portion where the temperature of the recording material exceeds the magnetic transition point due to laser irradiation is directed toward the external magnetic field during the cooling process. Since the magnetic transition point of the MnBi compound coincides with the primary structural phase transition point, a high temperature phase having a different crystal structure remains at room temperature as a metastable state during the cooling process during recording. Since the Kerr rotation angle of this high temperature phase is smaller than that of the NiAs type low temperature phase, the reproduction output is reduced. Also, in the process of repeating recording, erasing and reproducing, the high temperature phase in the metastable state
Since it transforms to a low temperature phase, recorded information cannot be stored.
The object of the present invention is to solve such conventional problems,
It is an object of the present invention to provide a magneto-optical recording medium which uses a MnBi-based compound as a recording material, which has a large reproduction signal and is excellent in repeated stability of recording / reproduction characteristics.

[0005]

According to the present invention, MnBi-X having a magnetic easy axis perpendicular to the film surface (where X is boron B) is used.
And at least one of carbon C is shown. The present invention is a magneto-optical recording medium characterized by using a compound having a composition represented by (4) as an information recording material.

[0006]

The structural phase transition of NiAs-type MnBi compound is M
It occurs when n moves from a hexacoordinate lattice position to a pentacoordinate lattice position. Therefore, the low temperature phase can be stabilized by previously filling the interstitial positions with other atoms. Since B and C have small ionic radii, they can selectively enter interstitial positions and suppress structural phase transition.

[0007]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a partial sectional view of a magneto-optical recording medium according to an embodiment of the present invention. In this magneto-optical recording medium, an intermediate layer (silicon nitride film formed by sputtering) 2 having a thickness of 95 nm is formed on a glass substrate 1 by using MnBi-B.
The layer (10 at% B) 3 is vapor-deposited to a thickness of 20 nm, the interference layer (sputtered silicon nitride film) 4 to a thickness of 20 nm, and the reflective layer (sputtered Al film) 5 to a thickness of 30 nm. It was filmed and heat treated to form a NiAs-type compound. When this recording medium was heated above the structural phase transition temperature and then rapidly cooled to room temperature, no change in Kerr rotation angle was observed. The MnBi-B layer can be formed by a vapor deposition method, a sputtering method, an ion plating method, an ion cluster beam method, or the like. The same effect was also observed in the MnBi-C recording layer.

[0008]

As described above, the Kerr rotation angle of the magneto-optical recording medium according to the present invention does not change even when it is rapidly cooled from the temperature above the magnetic transition point, and the present invention provides a high-performance magneto-optical recording medium. It has the effect of providing.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

[Explanation of symbols]

 1 Glass Substrate 2 Intermediate Layer 3 MnBi-B Layer 4 Interference Layer 5 Reflective Layer

Claims (1)

Claims: 1. MnB having a magnetic easy axis perpendicular to the film surface.
A magneto-optical recording medium comprising a compound having a composition represented by i-X (where X represents at least one of boron B and carbon C) as an information recording material.