JPH0423247A - Magneto-optical recording medium - Google Patents

Abstract

PURPOSE:To improve the recording and erasing magnetic field characteristics of reproducing C/N and to decrease the burden of an external magnetic field generating part by consisting a recording film of a rare earth metal/transition metal alloy film having perpendicular magnetic anisotropy and adding yttrium to this alloy film. CONSTITUTION:The recording film 14 consisting of the rare earth metal/ transition metal alloy film having the perpendicular magnetic anisotropy, for example, TbFeCoY film, is formed via protective layers 12, 13 on a substrate 11. The recording and erasing magnetic fields of the recording film necessary for the reproducing C/N to saturate are decreased by adding the yttrium to the TbFeCo film 14. The recording and erasing magnetic field characteristics are improved in this way and the burden of the external magnetic field generating part is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention records and erases signals by utilizing temperature rise caused by laser beam irradiation.1. This relates to a magneto-optical recording medium that reproduces signals using the magneto-optic effect. Conventional technology magneto-optical recording media use laser beam irradiation to locally raise the temperature of the recording film to a temperature higher than the compensation temperature or to a Curie temperature. Recording and erasing is performed by raising the temperature to around 300 degrees and magnetizing the recording film in the irradiated area in the direction of an external magnetic field (thermomagnetic recording), and the recording state of the recording film is changed by irradiating a laser beam with a power lower than the laser power used during recording erasing. Reproduction is performed by detecting the rotation of the polarization plane of reflected light or transmitted light depending on the direction of magnetization. Conventional recording methods include a method in which the temperature of the recording film is raised by irradiating laser light with a constant intensity, and thermomagnetic recording is performed using an external magnetic field whose direction is modulated according to the recording signal (
(magnetic field modulation recording method) and thermomagnetic recording method (optical magnetic recording method) in which the temperature of the recording film is locally raised by irradiating a laser beam whose intensity is modulated according to the recording signal under a constant external magnetic field (optical field modulation recording method). Furthermore, in order to perform high-density recording, magnetic materials with perpendicular magnetic anisotropy are used in the recording film of magneto-optical recording media. For high-speed recording, a magneto-optical recording medium with a small external magnetic field required for erasing records is desirable. Perpendicular magnetic anisotropy can be obtained relatively easily in the recording film of a conventional magneto-optical recording medium, and it is relatively magneto-optical. T with great effect
Rare earth metal-transition metal alloy films such as bFeC and O films, etc., are the problems that the invention aims to solve. However, conventional magneto-optical recording media such as those mentioned above
The external magnetic field required to saturate the reproduction CN ratio (the ratio of reproduction signal output to noise at the recording frequency) during erasing and recording is 200 (Oe) or more, which places a burden on the external magnetic field generation section of the recording device. In view of the above-mentioned problems, the present invention has the problem that conventional TbF eC hinders the miniaturization of recording devices and the increase in recording speed.

We are developing a magneto-optical recording medium that maintains the excellent properties of films, etc., improves the recording/erasing magnetic field characteristics of the reproduction CN ratio, reduces the burden on the external magnetic field generator, and enables miniaturization of recording devices and high-speed recording. Means for Solving the Problems In order to solve the above problems, a magneto-optical recording medium of the present invention is provided. Invention 1: The above-mentioned structure in which yttrium is added to a rare earth metal-transition metal alloy film such as a 1Tb Feco film saturates the regenerated CN ratio. Based on the fact that the recording/erasing magnetic field required for this purpose decreases with the amount of yttrium added, the recording/erasing magnetic field characteristics of the recording film are improved.

EXAMPLE Hereinafter, a magneto-optical recording medium according to an example of the present invention will be described with reference to the drawings.

FIG. 1 shows the structure of a magneto-optical recording medium in an embodiment of the present invention. In FIG. 1, 11 is a substrate made of glass or plastic, and 12 and 13 are Zn5.
Protective layer 14 made of eSiOs film is TbFeC
This is a recording film made of cY film. Here, the eight films on the substrate 11 are formed by sputtering or vapor deposition, and the thickness of each film is 80 to 1100 nm for the protective film 12 and the protective film 13.
In this example, the recording film 14 was set to have a thickness of 100 nm, and the composition of the recording film TbFe(,oYM) was as follows.
) +-zYz (where X is 0.18<X<0.28.Z
i;! O<'Z<0.15. W is 0.05'<W<0.
2a) FIG. 2 shows an example of the change in the recording and erasing magnetic field dependence of the reproduction CN ratio of the magneto-optical recording medium having the above structure, depending on the amount of yttrium added. Here, the dependence of the read/write CN ratio on the recording/erasing magnetic field is measured by using the optical modulation recording method, where recording and erasing is performed using the same magnetic field uX, and the moving speed of the magneto-optical recording medium VL is 6
('m/s), recording frequency Fm is 3°33 (MHz
)' is. As is clear from FIG. 2, by adding yttrium to the TbFeCo film, it is possible to reduce the recording/erasing magnetic field required to saturate the reproduction CN ratio.

In this embodiment, TbFeC・oY is used as the recording film 14.
DyFeCoy film GdTbFeY film with perpendicular magnetic anisotropy instead of TbFeC0Y film using M
A rare earth metal-transition metal alloy film such as a dTbFeCoY film may be used, and Pt, Cr, '
Metal elements such as Ti and AI may be added. Also
When a Zn5eSiO2 film is used as the protective film 12゜13, a chalcogenide film such as a ZnS film is used instead of the Zn5esi02 film, an oxide film such as a TaO2 film, or a SiN film.
A film of nitride such as a film or a film of a mixture thereof may be used.

Furthermore, the third plate has Al films 25 and 35 as shown in FIG.
The structure of a magneto-optical recording medium having a four-layer structure provided with a metal reflective film is also effective. As described above, the magneto-optical recording medium of the present invention has a structure in which the recording film is made of a rare earth metal-transition metal alloy film having perpendicular magnetic anisotropy, and the alloy film contains yttrium. By providing this, it is possible to improve the recording and erasing magnetic field characteristics of the reproduction CN ratio, reduce the burden on the external magnetic field generator, and enable miniaturization of the recording device and high-speed recording.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a magneto-optical recording medium according to an embodiment of the present invention. FIG. 2 is a diagram showing the dependence of the reproduction CN ratio on the recording/erasing magnetic field when adding yttrium in the magneto-optical recording medium according to an embodiment of the present invention. Characteristic text showing changes due to quantity Figure 3 is a block diagram of a magneto-optical recording medium in another embodiment of the present invention. Figure 4 is a block diagram of a magneto-optical recording medium in another embodiment of the present invention.
1.21.31...Substrate, 12, 13.22.23
．． 32, 33...Zn5esio2 trap 14.24.
34-=TbFeFeYJIL 25, 35...A
Name of agent: Patent attorney Shigetaka Awano Hakaichi Famous Confectionery Figure 1064 υθ 3θθ 4ρρOfficial Eiyu Ice Flower World (θe) 5ρ0 Figure 1

Claims (4)

[Claims] (1) A magneto-optical recording medium characterized in that the recording film is made of a rare earth metal-transition metal alloy film having perpendicular magnetic anisotropy, and the alloy film contains yttrium. (2) The alloy film has the general formula (R_XM_1_-_X)_1_-_ZY_Z (in the formula R
M represents at least one element from the rare earth metal group, and M represents at least one element from the transition metal group. 2. The magneto-optical recording medium according to claim 1, wherein the magneto-optical recording medium has a composition represented by the following: (3) The magneto-optical recording medium according to claim 2, wherein R consists of at least one element among Tb, Dy, and Gd, and M consists of at least one element among Fe and Co. (4) The alloy film is [Tb_X(Fe_1_-_WCo_W)_1_-_X
]_1_-_ZY_Z (in the formula, W is 0.05<W<0.2
) The magneto-optical recording medium according to claim 2.