JP2793083B2 - Magneto-optical recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called magneto-optical recording medium such as a rewritable magneto-optical disk, and more particularly, to a layer having a noble metal and a layer having a transition metal alternately laminated on a substrate. The present invention relates to a magneto-optical recording medium comprising:

[0002]

2. Description of the Related Art As an alternately laminated film of a noble metal / transition metal,
A conventional example is shown for the case of a Pt / Co laminated film. FIG. 2 shows a conventional magneto-optical recording medium. Pt layer 1 and C in the figure
In the structure in which the o-layer 2 is laminated on the substrate 4,
A super-thin film region of less than 00 ° becomes a perpendicular magnetization film, and the characteristics of the coercive force and the Kerr rotation angle change by changing the conditions such as the lamination period and the film thickness.

In order to increase the Kerr rotation angle and the coercive force, SiN, AlN,
Many reports have sandwiched a dielectric film such as ZnO. {Appl. Phys. Lett. 58 (2)
191 (1991)｝

[0004]

The alternating layered film of the noble metal / transition metal as described above has a larger magnetization than the conventional rare earth-transition metal alloy. Therefore, the stray magnetic field during recording increases. When recording is performed on a magneto-optical recording medium by the magnetic field modulation method, if the stray magnetic field is large, the recording sensitivity deteriorates, and recording cannot be performed with a low magnetic field.

SUMMARY OF THE INVENTION The present invention has been made to solve such a drawback, and it is an object of the present invention to improve the recording sensitivity in the magnetic field modulation recording of a magneto-optical recording medium comprising an alternately laminated noble metal / transition metal film.

[0006]

Means for Solving the Problems A substrate, an alternately laminated film formed on the substrate, the layer having a noble metal layer and a layer having a transition metal, and an in-plane magnetic layer formed on the alternately laminated film, A magnetic layer having an anisotropic Curie temperature of 100 ° C. to 300 ° C. is used.

[0007]

Since the Curie temperature of the in-plane magnetic film of the magnetic layer is close to the Curie temperature of the noble metal / transition metal alternately laminated film, the in-plane magnetic film is slightly magnetized in the direction of the external magnetic field during recording. The alternating laminated film is also magnetized by the exchange force from the in-plane magnetized film and the external magnetic field. As described above, since the exchange force from the in-plane magnetic film acts in the recording direction, it is possible to perform recording with a lower magnetic field as compared with the case where there is no in-plane magnetic film.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to a Pt / Co laminated film and
The case of an in-plane magnetized film will be described. FIG. 1 is a cross-sectional view showing the structure of a magneto-optical recording medium according to the present invention.
Layers 1 and Co layers 2 are alternately stacked, and a PtCo in-plane magnetized film is formed thereon.

Here, the film thickness per layer of the laminated film is Pt1
0-20 °, Co 3-10 °, and the total film thickness is 10
0-500 °. The PtCo in-plane magnetized film may be a laminated film or an alloy film.
The temperature must be 00 ° C., and when formed into a laminated film, the composition and the film thickness must be in a range not to become a perpendicular magnetization film. FIG. 3 is a schematic diagram when recording is performed on a magneto-optical recording medium. In the figure, 1 and 2 are laminated films, 3 is an in-plane magnetization film, 5 is a domain wall, and 6 is a laser beam.

When the temperature of the medium rises to near the Curie point due to the irradiation of the laser beam, the magnetic moment of the in-plane magnetized film rotates in the direction of the external magnetic field. Then, the magnetic moment of the laminated film also rotates in the direction of the external magnetic field due to the exchange force from the in-plane magnetized film and the external magnetic field. As described above, since the exchange force from the in-plane magnetic film acts in the direction of the external magnetic field, recording can be performed with a lower magnetic field than when there is no in-plane magnetic film.

FIG. 4 shows C / C when recorded by the magnetic field modulation method.
This shows the dependence of N on the external magnetic field. In a, a ZnO film was formed on a PC (polycarbonate) substrate at 800.degree., and after etching, a Pt / Co laminated film was formed. Here, the film thickness per Pt layer is 17 °
The film thickness per layer was 5 °, and nine layers were laminated. The Curie temperature is about 240 ° C. In the case b, a PtCo alloy was formed at about 50 ° on the Pt / Co laminated film of the disk having the structure a. The Co composition ratio of the PtCo alloy is 29 at.
% So that the Curie temperature is almost the same as that of the Pt / Co laminated film. Both a, a and b are overcoated with an ultraviolet curable resin for protection from scratches and the like. As shown in FIG. 4, the Pt / Co laminated film and the PtCo in-plane magnetic film are less deteriorated in C / N even if the external magnetic field is reduced than the Pt / Co laminated film alone, and the in-plane magnetic film It can be seen that the recording sensitivity is improved by exchange coupling. Here, the thickness of the PtCo alloy is set to 50
However, the characteristics do not change in the range of 20 to 1000 °, and the film thickness within this range is applicable.

Although the case where the Pt / Co laminated film is used as the laminated film is described above, the present invention can be applied to the case where another noble metal / transition metal such as Pd / Co is alternately laminated. Also,
The in-plane magnetized film can be applied even when another in-plane magnetized film having a Curie temperature of 100 to 300 ° C. such as PdCo or NdFeCo is used. Similar effects can also be obtained with a structure in which a dielectric film or an Al reflection film is formed as conventionally used.

[0013]

As described above, when an in-plane magnetized film is formed on an alternately laminated noble metal / transition metal film, recording with a low magnetic field becomes possible. Therefore, the characteristics are improved when the magnetic field modulation recording is performed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a magneto-optical recording medium according to the present invention.

FIG. 2 is a cross-sectional view showing a configuration of a conventional magneto-optical recording medium.

FIG. 3 is a schematic diagram when recording is performed on a magneto-optical recording medium.

FIG. 4 is a diagram showing the external magnetic field dependence of C / N when recording is performed by a magnetic field modulation method.

[Explanation of symbols]

 Reference Signs List 1 Pt layer (noble metal layer) 2 Co layer (transition metal layer) 3 PtCo in-plane magnetization layer (magnetic layer) 4 Substrate

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G11B 11/10 506

Claims (1)

(57) [Claims] 1. An alternately laminated film comprising a substrate, a layer having a noble metal and a layer having a transition metal formed on the substrate, and an in-plane magnetic anisotropic film formed on the alternately laminated film A magneto-optical recording medium comprising a magnetic layer having a property and a Curie temperature of 100 ° C. to 300 ° C.