JPH11134730A - Magneto-optical recording medium and reproducing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sufficient reproducing signal even when reproducing is performed based on a small recording bit diameter and a small recording bit interval by arranging a magnetic mask layer between a reproducing layer and a recording layer composed of a vertical magnetizing film magnetically connected with the reproducing layer for suppressing magnetic connection between the recording layer and the reproducing layer at a room temperature to be away from the reproducing layer. SOLUTION: An intrasurface magnetizing layer 3 is formed as a magnetic mask layer adjacent to a recording layer 4, magnetization from a part 11 not heated over a critical temperature in the recording layer 4 is masked by the intrasurface magnetizing layer 3. In other words, by the intrasurface layer 3, the influence of the magnetization of the part 11 of the recording layer 4 on a reproducing layer 1 is prevented. Thus, the mask of only a part over the critical temperature is eliminated and, even when a magnetic area existing in the reproducing layer 1 is larger in size than a recording magnetic area, information regarding only a desired magnetic area heated over the critical temperature in the recording layer 4 is reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magneto-optical recording medium such as a magneto-optical disk, a magneto-optical tape, a magneto-optical card, etc., applied to a magneto-optical recording and reproducing apparatus, and a reproducing method therefor.

[0002]

2. Description of the Related Art Conventionally, magneto-optical recording media have been put to practical use as rewritable optical recording media. In such a magneto-optical recording medium, the recording bit diameter and the recording bit interval, which are the magnetic domains for recording, are smaller than the beam diameter of the light beam emitted from the semiconductor laser focused on the magneto-optical recording medium. When this happens, there is a disadvantage that the reproduction characteristics deteriorate.

[0003] Such a drawback is that, since adjacent recording bits fall within the beam diameter of the light beam condensed on the target recording bits, individual recording bits cannot be separated and reproduced. That is the cause.

In order to solve the above-mentioned disadvantage, Japanese Patent Laid-Open No.
No. 150418, a structure in which a non-magnetic intermediate layer is provided between a reproducing layer and a recording layer which are in an in-plane magnetization state at room temperature and become perpendicular magnetization with a rise in temperature, and the reproduction layer and the recording layer are magnetostatically coupled. Has been proposed.

[0005] Thereby, the recording magnetic domain information of the portion in the in-plane magnetization state is masked, and even when adjacent recording bits fall within the beam diameter of the focused light beam, the individual recording bits are separated. It is shown that reproduction becomes possible (first conventional example).

Further, Appl. Phys. Lett. 6
9 (27) p4257-4259, "Magnetic
domain expansion readout
for amplification of an
ultra high density magnet
o-optical recording signa
l ″ has a similar configuration in which a nonmagnetic intermediate layer is interposed between the recording layer and the reproducing layer, and a magnetic field generated from the recording layer forms a magnetic domain larger than the magnetic domain of the recording layer in the reproducing layer. A magnetic domain enlarging system for transferring and reproducing is shown (second conventional example).

[0007]

However, in the above-mentioned first conventional example, when recording / reproducing is performed with a smaller recording bit diameter and a smaller recording bit interval, the reproduction signal intensity decreases, and a sufficient reproduction signal cannot be obtained. It was confirmed that there was a problem that it could not be obtained.

The second conventional example also has a high recording density,
If there are many bits under the reproducing magnetic domain, the reproducing layer receives the magnetic field from the multiple bits of the recording layer, and the reproducing layer can correctly receive the magnetic field from the bit to be truly reproduced. There was a problem that could not be done.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to achieve a sufficient reproduction even when recording and reproduction are performed with a small recording bit diameter and a smaller recording bit interval. To get the signal.

[0010]

The present invention has the following arrangement to achieve the above object.

The magneto-optical recording medium of claim 1 includes a reproducing layer in which at least a signal reproducing region is in a perpendicular magnetization state, and a recording layer made of a perpendicular magnetic film magnetically coupled to the reproducing layer. The medium is characterized by having a magnetic mask layer disposed at a distance from the reproducing layer and for suppressing magnetic coupling between the recording layer and the reproducing layer at least at room temperature.

According to another aspect of the present invention, there is provided a magneto-optical recording medium comprising: a reproducing layer in which at least a signal reproducing region is in a perpendicular magnetization state; and a recording layer made of a perpendicular magnetic film magnetically coupled to the reproducing layer. In a magneto-optical recording medium in which a magnetic domain larger than the recording magnetic domain of the recording layer is formed in the reproducing layer by beam irradiation, the magnetic coupling between the recording layer and the reproducing layer is arranged at least at room temperature at a distance from the reproducing layer. It has a magnetic mask layer to suppress.

According to a third aspect of the present invention, in the magneto-optical recording medium according to the first or second aspect, the magnetic mask layer comprises an in-plane magnetic layer whose magnetization decreases at a high temperature. And

According to a fourth aspect of the present invention, in the magneto-optical recording medium according to the third aspect, at room temperature, the magnetization of the magnetic mask layer is larger than the magnetization of the recording layer.

According to a fifth aspect of the present invention, in the magneto-optical recording medium according to the third or fourth aspect, the Curie temperature of the magnetic mask layer is lower than the Curie temperature of the recording layer. I do.

According to a sixth aspect of the present invention, in the magneto-optical recording medium according to any one of the third to fifth aspects, the Curie temperature of the recording layer is lower than the Curie temperature of the reproducing layer. Features.

According to a seventh aspect of the present invention, there is provided the magneto-optical recording medium according to any one of the third to sixth aspects, wherein a transparent dielectric layer, the reproducing layer, a non-magnetic intermediate layer, The magnetic mask layer, the recording layer, and the protective layer are sequentially formed.

According to an eighth aspect of the present invention, in the magneto-optical recording medium according to the seventh aspect, the thickness of the magnetic mask layer is 2 nm or more and 40 nm or less.

According to a ninth aspect of the present invention, in the magneto-optical recording medium according to the seventh or eighth aspect, the magnetic mask layer is made of a GdFe alloy, a GdFeAl alloy, a GdF
eTi alloy, GdFeTa alloy, GdFePt alloy, G
dFeAu alloy, GdFeCu alloy, GdFeAlTi
Alloy or a GdFeAlTa alloy.

According to a tenth aspect of the present invention, there is provided a magneto-optical recording medium.
10. The magneto-optical recording medium according to claim 1, wherein the magnetic mask layer is made of (Gd _0.11 Fe _0.89 ) _X Al.
It is represented by a composition formula of _1-X , wherein X (atom ratio) is 0.30 or more and 1.00 or less.

[0021] The magneto-optical recording medium of claim 11 is claim 7.
11. The magneto-optical recording medium according to claim 1, wherein the Curie temperature of the magnetic mask layer is 60 ° C. or higher.
It is characterized by being at most 20 ° C.

According to a twelfth aspect of the present invention, there is provided a magneto-optical recording medium.
Alternatively, in the magneto-optical recording medium according to claim 2, the magnetic mask layer is formed of a magnetic layer whose total magnetization direction is opposite to that of the recording layer at least at room temperature.

According to a thirteenth aspect of the present invention, there is provided the magneto-optical recording medium according to the first aspect.
3. The magneto-optical recording medium according to 2, wherein the recording layer is made of a transition metal-rich rare earth transition metal alloy film from room temperature to a Curie temperature, and the magnetic mask layer is at least room temperature at a rare earth metal rich. A perpendicular magnetization film made of a rare earth transition metal alloy formed such that the direction of the transition metal sublattice magnetization of the layer follows the direction of the transition metal sublattice magnetization of the recording layer.

According to a fourteenth aspect of the present invention, there is provided a magneto-optical recording medium.
2 or the magneto-optical recording medium according to claim 13,
The magnetic mask layer is made of a magnetic film whose magnetization decreases at a high temperature.

According to a fifteenth aspect of the present invention, there is provided a magneto-optical recording medium.
15. The magneto-optical recording medium according to claim 2, wherein a total magnetization of the magnetic mask layer at room temperature is substantially the same as a total magnetization of the recording layer at room temperature.

[0026] The magneto-optical recording medium of claim 16 is claim 1.
16. The magneto-optical recording medium according to claim 2, wherein the Curie temperature of the magnetic mask layer is lower than the Curie temperature of the recording layer.

[0027] The magneto-optical recording medium of claim 17 is claim 1.
17. The magneto-optical recording medium according to claim 2, wherein a compensation temperature of the magnetic mask layer is lower than a Curie temperature of the recording layer.

[0028] The magneto-optical recording medium of claim 18 is claim 1.
18. The magneto-optical recording medium according to claim 2, wherein a transparent dielectric layer, the reproducing layer, the non-magnetic intermediate layer, the magnetic mask layer, the recording layer, and the protective layer are sequentially formed on the substrate. It is characterized by becoming.

[0029] The magneto-optical recording medium of claim 19 is claim 1.
8. The magneto-optical recording medium according to 8, wherein the thickness of the magnetic mask layer is 10 nm or more and 60 nm or less.

According to a twentieth aspect of the present invention, there is provided a magneto-optical recording medium.
18. The magneto-optical recording medium according to claim 2, wherein a transparent dielectric layer, the reproducing layer, the non-magnetic intermediate layer, the recording layer, the magnetic mask layer, and the protective layer are sequentially formed on the substrate. It is characterized by becoming.

The magneto-optical recording medium of claim 21 is claim 2
0, wherein the thickness of the magnetic mask layer is 10 nm or more and 80 nm or less.

[0032] The magneto-optical recording medium of claim 22 is claim 1.
22. The magneto-optical recording medium according to claim 8, wherein the magnetic mask layer is made of a GdDyFe alloy, TbF
e alloy, DyFe alloy, GdFe alloy, GdTbFe alloy, DyFeCo alloy, and TbFeCo alloy.

[0033] The magneto-optical recording medium of claim 23 is claim 1.
23. The magneto-optical recording medium according to claim 8, wherein the Curie temperature of the magnetic mask layer is 80 ° C. or more and 220 ° C. or less.

According to a twenty-fourth aspect of the present invention, there is provided the magneto-optical recording medium according to the first aspect.
24. The magneto-optical recording medium according to claim 8, wherein the compensation temperature of the magnetic mask layer is 80 ° C. or higher.
It is characterized by having a temperature of 20 ° C. or less.

According to a twenty-fifth aspect of the present invention, there is provided the magneto-optical recording medium according to the first aspect.
Alternatively, in the magneto-optical recording medium according to claim 2, the magnetic mask layer is a magnetic film having an in-plane magnetization state at room temperature and a perpendicular magnetization state at a predetermined temperature or higher.

[0036] The magneto-optical recording medium of claim 26 is claim 2.
5. The magneto-optical recording medium according to 5, wherein a Curie temperature of the magnetic mask layer is lower than a Curie temperature of the recording layer.

[0037] The magneto-optical recording medium of claim 27 is claim 2.
5 or the magneto-optical recording medium according to claim 26,
The Curie temperature of the recording layer is lower than the Curie temperature of the reproducing layer.

[0038] The magneto-optical recording medium of claim 28 is claim 2.
28. The magneto-optical recording medium according to claim 5, wherein a transparent dielectric layer, the reproducing layer, the non-magnetic intermediate layer, the magnetic mask layer, the recording layer, and the protective layer are sequentially formed on the substrate. It is characterized by becoming.

The magneto-optical recording medium according to claim 29 is claim 2
9. The magneto-optical recording medium according to 8, wherein the thickness of the magnetic mask layer is 2 nm or more and 40 nm or less.

The magneto-optical recording medium according to claim 30 is claim 2
8 or the magneto-optical recording medium according to claim 29,
The magnetic mask layer includes GdFeCo, GdNdFe, G
dNdFeCo, GdTbFe, GdTbFeCo, G
It is characterized by being made of any alloy of dDyFeCo, GdDyFe and GdFe.

The magneto-optical recording medium of claim 31 is claim 2
31. The magneto-optical recording medium according to claim 8, wherein the magnetic mask layer is formed of Gd _x (Fe _0.80 Co
_0.20 ) It is represented by a composition formula of _1-X , wherein X (atom ratio) is 0.1.
It is characterized by being 10 or more and 0.35 or less.

A magneto-optical recording medium according to claim 32 is the magneto-optical recording medium according to claim 7, 18, 20, or 28, wherein the thickness of the reproducing layer is 10n.
m or more and 80 nm or less.

A magneto-optical recording medium according to claim 33 is the magneto-optical recording medium according to claim 7, 18, 20, or 28, wherein the thickness of the non-magnetic intermediate layer is:
The thickness is 1 nm or more and 80 nm or less.

A magneto-optical recording medium according to claim 34 is the magneto-optical recording medium according to claim 7, 18, 20, or 28, wherein the non-magnetic intermediate layer has a reflection on the recording layer side. A layer is formed adjacent to the non-magnetic intermediate layer.

The magneto-optical recording medium of claim 35 is claim 3
5. The magneto-optical recording medium according to 4, wherein the reflective layer is made of Al.
And a film thickness of 2 nm or more and 40 nm or less.

The magneto-optical recording medium of claim 36 is claim 3.
5. The magneto-optical recording medium according to 4, wherein the reflective layer is made of Al.
And a magnetic metal.

The magneto-optical recording medium of claim 37 is claim 3.
6. The magneto-optical recording medium according to 6, wherein the reflective layer is
It is represented by a composition formula of l _1-x Fe _x , wherein X (atom ratio) is 0.02 or more and 0.50 or less.

The magneto-optical recording medium of claim 38 is claim 3
6. The magneto-optical recording medium according to 6, wherein the reflective layer is
It is represented by a composition formula of l _{1 -X} Ni _X , wherein X (atom ratio) is 0.02 or more and 0.50 or less.

The magneto-optical recording medium according to claim 39 is claim 3
5. The magneto-optical recording medium according to 4, wherein the reflective layer is made of Al.
And a nonmagnetic metal alloy.

The magneto-optical recording medium according to claim 40 is claim 3.
9. The magneto-optical recording medium according to 9, wherein the non-magnetic metal is any one of Ti, Ta, Pt, Au, Cu, and Si.

The magneto-optical recording medium of claim 41 is claim 3
9. The magneto-optical recording medium according to 9, wherein the nonmagnetic metal is represented by a composition formula of Al _1-x Ti _x , and X (atom ratio) is 0.02 or more and 0.98 or less.

A magneto-optical recording medium according to claim 42 is the magneto-optical recording medium according to claim 7, 18, 20, or 28, wherein: The heat radiation layer is formed.

[0053] The magneto-optical recording medium of claim 43 is claim 1.
43. The magneto-optical recording medium according to claim 42, wherein the reproducing layer has an in-plane magnetization state at room temperature and a perpendicular magnetization state at high temperature.

[0054] The magneto-optical recording medium of claim 44 is claim 1, claim 2, claim 3, claim 12 or claim 25.
In the magneto-optical recording medium described in the above, the reproducing layer is made of Co
And Pt are alternately laminated.

A method for reproducing information from a magneto-optical recording medium according to claim 45 is a reproducing method for reproducing information from a magneto-optical recording medium according to any one of claims 1 to 44, wherein the magneto-optical recording medium is reproduced when a signal is reproduced. Is irradiated with a light beam in a pulse shape.

A reproducing method of a magneto-optical recording medium according to claim 46 is a reproducing method for reproducing information from a magneto-optical recording medium according to claim 3 or 14, wherein the reproducing method includes the steps of: The method is characterized in that the magnetic mask layer is heated to a temperature close to its Curie temperature by irradiating a beam.

A reproducing method for a magneto-optical recording medium according to claim 47 is a reproducing method for reproducing information from a magneto-optical recording medium according to claim 25, wherein the magneto-optical recording medium is irradiated with a light beam during reproduction. And heating the magnetic mask layer to the predetermined temperature or higher.

The magneto-optical recording medium of claim 48 is the first invention.
8. The magneto-optical recording medium according to claim 1, wherein the magnetic mask layer is magnetostatically coupled to the recording layer.

The magneto-optical recording medium of claim 49 is claim 2
The magneto-optical recording medium according to any one of claims 5 to 28, wherein the magnetic mask layer is magnetostatically coupled to the recording layer.

[0060] The magneto-optical recording medium of claim 50 is claim 4.
The magneto-optical recording medium according to claim 8 or 49,
A non-magnetic intermediate layer is formed between the magnetic mask layer and the recording layer, and the thickness of the non-magnetic intermediate layer is 2 nm or more and 80 nm or less.

[0061]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) Hereinafter, Embodiment 1 of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of a magneto-optical recording medium illustrating the principle of reproduction of the magneto-optical disk of the present invention, and FIG. 16 is a cross-sectional view illustrating the principle of reproduction of a conventional magneto-optical disk.

First, a conventional super-resolution reproducing operation will be described. In the conventional reproducing method, as shown in FIG.
Is reproduced by the reproducing layer 1 and transferred to a magnetic domain of the reproducing layer 1. For this reason, at least when the temperature rises, the reproducing layer 1 made of an alloy of a rare earth metal and a transition metal, which is in a perpendicular magnetization state, and the recording layer 4 made of an alloy of a rare earth metal and a transition metal having a compensation temperature at room temperature. A non-magnetic intermediate layer 2 is formed therebetween, and the reproducing layer 1 and the recording layer 4 are magnetostatically coupled.

Here, when the light beam 5 is condensed and irradiated from the reproducing layer side, a Gaussian distribution temperature distribution corresponding to the intensity distribution of the light beam 5 is formed on the medium. With the formation of this temperature distribution, the magnetization of the recording layer 4 increases and the magnetic field generated from the recording layer 4 increases, and the magnetization direction of the reproducing layer 1 is determined by the magnetic field. Layer 4
Is transferred. By reproducing the information of the transferred portion, a super-resolution reproducing operation is realized.

In this reproducing method, as shown in FIG. 2A, the size of the magnetic domain existing in the reproducing layer 1 is adjusted to the beam spot size when a laser having a wavelength of 680 nm is used as a reproducing laser. If the size is set to about 1 μm and larger than the size of the magnetic domain of the recording layer 4, the signal generated from the reproducing layer 1 at the time of reproducing increases.

However, the direction of magnetization in the reproducing layer 1 is determined by the magnetic field from the recording layer 4.
When information is recorded on the recording layer 4 at a high density, the magnetization transfer from the recording layer 4 cannot be performed well as described below. That is, in the state where the isolated bits 100 are formed in the entire erase state as shown in FIG. 2A, the direction of the perpendicular magnetization in the reproducing layer 1 is effectively affected by only the influence of the magnetic field from the isolated bits 100. When recording is performed at a high density, the adjacent recording bit 101 is recorded as shown in FIG.
The effect comes out. Since the magnetization direction of the adjacent bit 101 is opposite to that of the recording bit 100, the magnetization to be originally reproduced is weakened, and magnetic transfer and magnetic expansion become extremely difficult. For this reason, information in a target range cannot be correctly reproduced, and the information is easily affected by an external floating magnetic field or the like.

On the other hand, in the magnetic domain enlarged magneto-optical recording medium of the present invention shown in FIG. 1, an in-plane magnetic layer 3 (a magnetic mask layer in the claims) is formed adjacent to the recording layer 4.
The in-plane magnetization layer 3 masks the magnetization from the portion 11 of the recording layer 4 that is not heated to a predetermined temperature (hereinafter, referred to as a critical temperature) or higher. That is, by the in-plane magnetization layer 3,
This prevents the magnetization of the portion 11 of the recording layer 4 from affecting the reproducing layer 1 (suppresses leakage of the magnetic flux generated from the portion 11 to the reproducing layer 1). In short, the magnetic coupling force between the recording layer 4 and the reproducing layer 1 is suppressed.

As described above, by realizing the magnetic mask, it is possible to remove the mask only at a portion higher than the critical temperature, and as shown in FIG. 1, the size of the magnetic domain existing in the reproducing layer 1 is smaller than that of the recording magnetic domain. Even in the case where the size is larger than the size, it is possible to reproduce only information of a desired recording magnetic domain heated to a critical temperature or higher in the recording layer 4.

Here, the in-plane magnetic layer 3 has magnetization at a temperature higher than the critical temperature in order to effectively work the magnetostatic coupling between the recording layer 4 and the reproducing layer 1 in a portion heated above the critical temperature. It is preferable that the magnetization is not present or the magnetization is smaller than the magnetization at a temperature lower than the critical temperature, and the Curie temperature of the in-plane magnetic layer 3 is lower than the Curie temperature of the recording layer 4. Is desirable. Further, in order to suppress the magnetic flux from the recording layer 4 from affecting the reproducing layer 1 at room temperature, it is desirable that the magnitude of the magnetization of the in-plane magnetization layer 3 be larger than the magnitude of the magnetization of the recording layer 4 at room temperature. .

When the reproducing layer 1 is reproduced with a laser beam, it is preferable that the size of the magnetic domain is large because the signal amount increases and the cause of noise is reduced. In addition, the domain wall needs to move according to the magnetic field from the recording layer 4, and a characteristic having a small coercive force is advantageous.

When information is reproduced from this magneto-optical recording medium, once the magnetic domains formed in the reproducing layer 1 are erased, which leads to a smooth reproducing operation, the reproducing laser beam is pulsed. When light is emitted, the magnetic domains are extinguished while the laser is extinguished, and the medium temperature is raised while the laser is emitting, and the recording magnetic domains of the recording layer are transferred to the reproducing layer for signal reproduction. And the quality of the reproduced signal can be made higher.

The first embodiment of the present invention will be described more specifically with reference to FIG. Hereinafter, a case where a magneto-optical disk is applied as a magneto-optical recording medium will be described.

As shown in FIG. 3, the magneto-optical disk according to this embodiment has a substrate 6, a transparent dielectric layer 7, a reproducing layer 1,
Non-magnetic intermediate layer 2, in-plane magnetization layer 3, recording layer 4, protective layer 8,
The overcoat layer 9 has a disk body laminated in this order.

In such a magneto-optical disk, a Curie temperature recording method is used as a recording method, and a light beam 5 emitted from a semiconductor laser is focused on the reproducing layer 1 by an objective lens, which is known as a polar Kerr effect. Information is recorded and reproduced by the magneto-optical effect. The polar Kerr effect is a phenomenon in which the direction of rotation of the polarization plane of reflected light is rotated by magnetization perpendicular to the incident surface.
This is a phenomenon in which the direction of rotation changes depending on the direction of magnetization.

The substrate 6 is made of, for example, a transparent substrate such as polycarbonate and is formed in a disk shape.

The transparent dielectric layer 7 is made of AlN, SiN, Al
It is desirable to use a material having a large refractive index such as SiN or TiO ₂ , and the film thickness is set so as to realize a good interference effect on the incident laser light and to increase the Kerr rotation angle of the medium. When the wavelength of the reproduction light is λ and the refractive index of the transparent dielectric layer 7 is n, the thickness of the transparent dielectric layer 7 is set to about (λ / 4n). For example, when the wavelength of the laser light is 680 nm, the thickness of the transparent dielectric layer 7 may be set to about 30 nm to 100 nm.

The reproducing layer 1 is a magnetic film made of a rare earth transition metal alloy, and its composition is adjusted so that its magnetic properties are in an in-plane magnetization state at room temperature and become a perpendicular magnetization state as the temperature rises.

The nonmagnetic intermediate layer 2 is made of AlN, SiN, Al
The reproducing layer 1 and the recording layer 4 are composed of one layer of a dielectric such as SiN, one layer of a nonmagnetic metal alloy such as Al, Ti, and Ta, or two layers of the dielectric and the metal. The total film thickness is set to 1 to 80 nm for coupling.

The in-plane magnetic layer 3 is a magnetic film mainly composed of a rare earth transition metal alloy or a rare earth metal or a transition metal, and has a magnetization in a direction parallel to the film surface. As described in FIG. 1, the in-plane magnetic layer 3 masks the magnetic field generated from the perpendicular magnetization of the recording layer 4 at the temperature equal to or lower than the critical temperature by the in-plane magnetization, thereby preventing the leakage of the magnetic field to the reproducing layer 1. Above the critical temperature, the composition is adjusted so that the mask effect of magnetization is lost and the magnetic flux generated from the recording layer 4 is easily transmitted to the reproducing layer.

The recording layer 4 is composed of a perpendicular magnetization film made of a rare earth transition metal alloy, and its thickness is set in the range of 20 to 80 nm.

The protective layer 8 is made of AlN, SiN, AlSi
It is made of a dielectric material such as N or SiC or a non-magnetic metal alloy such as Al, Ti or Ta, and is formed for the purpose of preventing the rare earth transition metal alloy used for the reproducing layer 1 and the recording layer 4 from being oxidized. And its film thickness is set in the range of 5 nm to 60 nm.

The overcoat layer 9 is formed by applying an ultraviolet curable resin or a thermosetting resin by spin coating, and irradiating ultraviolet rays or heating.

Hereinafter, a specific example of the magneto-optical disk having the above-described configuration will be described with respect to (1) a forming method and (2) recording / reproducing characteristics.

(1) Formation Method First, an Al target, a GdFeCo alloy target, a GdFeAl alloy target, and a GdDyFeCo
In the sputtering device equipped with each alloy target,
A polycarbonate substrate 6 having a pregroove and prepits and formed in a disk shape is placed on a substrate holder. After the inside of the sputtering apparatus was evacuated to 1 × 10 ⁻⁶ Torr, a mixed gas of argon and nitrogen was introduced, power was supplied to the Al target, and the gas pressure was 4 × 10 ⁻³ Torr.
Under the conditions described above, a transparent dielectric layer 7 made of AlN was formed on the substrate 6 to a thickness of 80 nm.

Next, the inside of the sputtering apparatus is again set to 1 × 10 ^−6.
After evacuating to Torr, introducing argon gas,
Electric power is supplied to the GdFeCo alloy target, the gas pressure is set to 4 × 10 ⁻³ Torr, and G
A reproducing layer 1 made of d _0.30 (Fe _0.80 Co _0.20 ) _0.70 was formed with a thickness of 20 nm. The reproducing layer 1 had a property of being in an in-plane magnetization state at room temperature, and having a property of being a perpendicular magnetization state at a temperature of 120 ° C., its compensation temperature was 300 ° C., and its Curie temperature was 320 ° C.

Next, a mixed gas of argon and nitrogen is introduced, power is supplied to the Al target, and a gas pressure of 4 × 10
^Under the condition of ^-3 Torr, a nonmagnetic intermediate layer 2 of AlN was formed on the reproducing layer 1 to a thickness of 20 nm.

Next, an electric power is supplied to the GdFeAl alloy target, the gas pressure is set to 4 × 10 ⁻³ Torr, and an in-plane magnetic layer made of (Gd _0.11 Fe _0.89 ) _0.75 Al _{0.25 is formed} on the nonmagnetic intermediate layer 2. 3 was formed with a thickness of 30 nm. The in-plane magnetic layer 3 had a Curie temperature of 120 ° C. and had magnetization in a direction parallel to the film surface from room temperature to the Curie temperature.

Next, the inside of the sputtering apparatus is again set to 1 × 10 ^−6.
After evacuating to Torr, introducing argon gas,
Electric power is supplied to the GdDyFeCo alloy target, the gas pressure is set to 4 × 10 ⁻³ Torr, and on the in-plane magnetization layer 3,
A recording layer 4 of (Gd _0.50 Dy _0.50 ) _0.23 (Fe _0.80 Co _0.20 ) _0.77 was formed with a thickness of 40 nm. The recording layer 4 has a compensation temperature of 25 ° C. and a Curie temperature of 275.
° C.

Next, a mixed gas of argon and nitrogen is introduced, power is supplied to the Al target, and a gas pressure of 4 × 10
^Under the condition of ^-3 Torr, a protective layer 8 of AlN was formed on the recording layer 4 to a thickness of 20 nm.

Next, an ultraviolet curable resin was applied on the protective layer 8 by spin coating, and irradiated with ultraviolet rays to form an overcoat layer 9.

(2) Recording / Reproducing Characteristics FIG. 4 shows the mark length dependence of the CNR (signal to noise ratio) of the above disk measured by an optical pickup using a semiconductor laser having a wavelength of 680 nm. Here, the above-described magneto-optical recording medium of the present embodiment is shown as Example 1.

For comparison, the mark length dependence of the CNR of a magneto-optical disk having no in-plane magnetic layer 3 is also shown in FIG. The medium of the magneto-optical disk having no in-plane magnetic layer has a configuration in which the in-plane magnetic layer 3 is removed from the medium configuration of the present embodiment. The mark length dependency of the CNR shown here indicates a signal-to-noise ratio when a recording magnetic domain having a length corresponding to the mark length is continuously formed at a recording magnetic domain pitch twice as long as the mark length. is there.

When the CNRs of both the marks having a mark length of 0.3 μm are compared, the CNRs of Comparative Example 1 are 34.0 dB, whereas the CNRs of Example 1 are 41.5 dB and 7.5 dB, respectively. ing. This is due to the fact that the magnetization mask for the recording layer 4 was effective by the in-plane magnetization layer 3 and the reproduction resolution was improved.

Next, Table 1 shows the reproduction layer 1 in Example 1.
And the thickness of the in-plane magnetic layer 3 were changed, and the CNR at 0.3 μm was changed.
3 shows the results of the measurement.

[0095]

[Table 1]

In Table 1, the in-plane magnetic layer thickness of 0 nm corresponds to
The result of Comparative Example 1 in which the in-plane magnetization layer 3 is not formed is shown. Even when the thickness of the in-plane magnetic layer 3 is extremely thin, such as 2 nm, the strengthening of the in-plane magnetic mask increases the CNR by 1 dB. As the thickness of the in-plane magnetic layer 3 is increased up to 30 nm, the strengthening of the in-plane magnetic mask increases the CNR. However, if the thickness is further increased, the CNR decreases. This means that the recording layer and the reproduction layer are separated. This is considered to be due to the fact that the in-plane magnetization mask was excessively strengthened and the magnetic aperture became difficult to open, so that a perfect perpendicular magnetization state of the reproducing layer could not be obtained. From the above, it is understood that the film thickness of the in-plane magnetic layer 3 in which the CNR is higher than that of Comparative Example 1 is in the range of 2 to 40 nm.

When the thickness of the reproducing layer 1 is set to 8 nm,
The reproduced signal becomes smaller, and its CNR becomes lower than that of Comparative Example 1. Further, the thickness of the reproducing layer 1 is set to 120 nm.
In this case, the domain wall energy generated in the reproducing layer 1 increases, and a complete perpendicular magnetization state cannot be obtained in a portion where the temperature is increased, and its CNR becomes lower than that in Comparative Example 1. From Table 1, it can be seen that the thickness of the reproducing layer 1 having a higher CNR than that of Comparative Example 1 is in the range of 10 to 80 nm.

Next, Table 2 shows that the CNR at 0.3 μm and the thickness of the nonmagnetic intermediate layer 2 in Example 1 were changed and
It shows the result of measuring the magnetic field required for erasing (erasing magnetic field).

[0099]

[Table 2]

As shown in Table 2, the thickness of the non-magnetic intermediate layer 2 was 0.5
In the case of nm, it can be seen that the CNR is significantly reduced. This is presumably because the nonmagnetic intermediate layer 2 was too thin to obtain a good magnetostatic coupling state. When the thickness of the nonmagnetic intermediate layer 2 is 1 nm, the maximum CNR is obtained, and as the thickness of the nonmagnetic intermediate layer 2 increases, the magnetostatic coupling force decreases and the CNR decreases. . CNR higher than Comparative Example 1
In order to obtain, the thickness of the nonmagnetic intermediate layer 2 is 1 to 80 nm.
It is understood that it is necessary to set in the range of.

Further, it can be seen that by increasing the thickness of the nonmagnetic intermediate layer 2, the magnetostatic coupling force between the reproducing layer 1 and the recording layer 4 is reduced, and the erasing magnetic field is reduced. In order to keep the erasing magnetic field within a practical range of 31 kA / m or less, it is more desirable that the thickness of the nonmagnetic intermediate layer 2 be 4 nm or more.

(Embodiment 2) In this embodiment, an example will be described in which the in-plane magnetic layer 3 having a different composition is used in the specific example of the magneto-optical disk shown in Embodiment 1 described above.

In the first embodiment, the in-plane magnetic layer 3 has a Curie temperature of 120 ° C. (Gd _0.11 Fe _0.89 ).
The recording and reproduction characteristics when _0.75 Al _0.25 was used were shown.
In the present embodiment, the results of investigating the recording / reproducing characteristics by changing the Al content of the in-plane magnetic layer 3 will be described.

Table 3 shows that the in-plane magnetic layer 3 is (Gd _0.11 Fe _0.89 ) _X Al _1-X having a film thickness of 30 nm, and X (atom)
Ratio), the Curie temperature T of the in-plane magnetic layer 3 is changed.
_It shows the result of measuring _C2 and the CNR (signal-to-noise ratio) at 0.3 μm measured by an optical pickup using a semiconductor laser having a wavelength of 680 nm.

[0105]

[Table 3]

In Table 3, the CNR (34.0 dB) obtained in Comparative Example 1 in which the in-plane magnetic layer 3 was not formed.
Higher CNR is obtained when 0.30 <X <1.0
It can be seen that the range is 0. The reproducing layer 1 used in the present embodiment is the same as that of the first embodiment,
At a temperature of 0 ° C., the state becomes a perpendicular magnetization state. In other words, the in-plane magnetic layer 3 only needs to be able to mask the magnetic field of the recording layer at the temperature of 120 ° C. or less.
The optimal value of the Curie temperature is about 120 ° C. However, as shown in the present embodiment, the in-plane magnetization layer 3
When the Curie temperature is 60 ° C. or more and 220 ° C. or less, a higher CNR than that of Comparative Example 1 is obtained. It is possible to do.

Further, in the present embodiment, the result using GdFeAl as the in-plane magnetization layer 3 is described, but the Curie temperature range (60 ° C. to 220 ° C.) is used.
Suffices to satisfy the in-plane magnetization.
It is possible to use the in-plane magnetization layer 3 made of e, NdFeAl, DyFe, DyFeAl.

(Embodiment 3) In the present embodiment, an example in which another material is used as the in-plane magnetization layer 3 in the specific example of Embodiment 1 will be described.

In the first embodiment, the recording / reproducing characteristics when (Gd _0.11 Fe _0.89 ) _0.75 Al _0.25 having a Curie temperature of 120 ° C. is used. In the present embodiment, the in-plane magnetic layer 3 is used. Will be described as a result of using a metal element other than Al.

Table 4 shows the Curie temperature T _C2 of the in-plane magnetic layer 3 when (Gd _0.11 Fe _0.89 ) _0.75 Z _0.25 with a film thickness of 20 nm was used for the in-plane magnetic layer 3 and the semiconductor laser having a wavelength of 680 nm. 4 shows the result of measuring the CNR (signal-to-noise ratio) at 0.3 μm measured by the optical pickup. Here, as Z, Ti, Ta, Pt, Au,
Cu, Al _0.5 Ti _0.5 , and Al _0.5 Ta _0.5 were used.

[0111]

[Table 4]

From Table 4, as Z, Ti, Ta, Pt,
It can be seen that in all cases using Au, Cu, Al _0.5 Ti _0.5 , and Al _0.5 Ta _0.5 , a higher CNR than that of Comparative Example 1 was obtained. As described in the second embodiment, the Curie temperature of in-plane magnetic layer 3 is 60 ° C. to 22 ° C.
The temperature may be in the range of 0 ° C., NdFeTi, NdF
It is possible to use an in-plane magnetization layer made of eTa, DyFeTi, and DyFeTa.

(Embodiment 4) Embodiment 4 of the present invention is described below with reference to FIG. In the present embodiment, a case where a magneto-optical disk is applied as a magneto-optical recording medium will be described. However, Embodiment 1
Descriptions of the same parts as those of Nos. 1 to 3 are omitted.

The magneto-optical disk according to the fourth embodiment is
As shown in FIG. 5, the substrate 6, the transparent dielectric layer 7, the reproducing layer 1, the non-magnetic intermediate layer 2, the reflective layer 10, the in-plane magnetic layer 3, the recording layer 4, the protective layer 8, and the overcoat layer 9 It has disk bodies stacked in this order.

In the first embodiment, when the thickness of the in-plane magnetic layer 3 is smaller than 10 nm, the light beam 5 transmitted through the reproducing layer 1 and the non-magnetic intermediate layer 2 is reflected by the recording layer 4, The information of the recording layer 4 is mixed in the reproduction signal.

The magneto-optical disk according to the fourth embodiment is the same as the magneto-optical disk according to the first embodiment except that the reflection layer 10 is formed between the nonmagnetic intermediate layer 2 and the in-plane magnetic layer 3. have. By doing so, the light beam 5 transmitted through the reproduction layer 1 is reflected by the reflection layer 10, and
It is possible to prevent unnecessary information of the recording layer 4 from being mixed into the reproduction signal.

Hereinafter, a specific example of the magneto-optical disk according to the present embodiment will be described with respect to (1) a forming method and (2) recording / reproducing characteristics.

(1) Forming Method The magneto-optical disk of this embodiment is the same as the method of forming a magneto-optical disk of Embodiment 1 except that the non-magnetic intermediate layer 2 and the in-plane magnetic layer 3 are made of Al. A reflective layer 10 is formed, and a substrate 6, a transparent dielectric layer 7, a reproducing layer 1, a non-magnetic intermediate layer 2, an in-plane magnetic layer 3, a recording layer 4, a protective layer 8, and an overcoat layer 9 As in the first embodiment, the thickness of the reproducing layer 1 is set to 17.5 nm, and the thickness of the in-plane magnetic layer 3 is set to 7.5 nm.
Formed.

Here, after forming the non-magnetic intermediate layer 2, the Al reflective layer 10 is again exposed to 1 × 10 ⁻⁶ T in the sputtering apparatus.
after evacuating to orr and introducing argon gas, A
l Supply power to the target and set the gas pressure to 4 × 10 ^-3 To
rr, a reflective layer 10 made of Al was formed on the nonmagnetic intermediate layer 2 with a thickness of 2 to 80 nm.

(2) Recording / reproducing characteristics Table 5 shows that the thickness of the reflective layer 10 in the magneto-optical disk of the present embodiment was changed, and 0.3 μm was measured with an optical pickup using a semiconductor laser having a wavelength of 680 nm. CNR
(Signal-to-noise ratio).

[0121]

[Table 5]

In Table 5, the thickness of the reflective layer of 0 nm indicates the result of Comparative Example 2 in which the reflective layer 10 was not formed.
Even when the thickness of the reflective layer 10 is extremely thin, such as 2 nm, the effect of blocking information reproduction from the recording layer 4 can be seen.
The NR increases by 1.0 dB. By increasing the thickness of the reflective layer 10, the CNR gradually increases, and the thickness 20
The CNR becomes maximum at nm. This is because the effect of blocking information reproduction from the recording layer 4 becomes more remarkable as the thickness of the reflective layer increases. Although the CNR is reduced when the film thickness is 30 nm or more, the magnetostatic coupling force acting between the recording layer 4 and the reproducing layer 1 becomes weaker as the distance between the recording layer 4 and the reproducing layer 1 increases. From the above, C higher than Comparative Example 2 was obtained.
In order to obtain NR, the thickness of the reflective layer 10 is set to 2 to 50 nm.
It is understood that it is necessary to set within the range.

(Embodiment 5) In this embodiment, a case where a different material is used as the reflective layer 10 in the specific example of Embodiment 4 will be described.

In the fourth embodiment, the reproduction characteristics using Al are described. However, in the present embodiment, in order to improve the recording characteristics, Al and A are used as the reflection layer 10.
The results using alloys with metals other than 1 will be described.

Table 6 shows that the reflective layer 10 is made of Al having a thickness of 20 nm.
By changing the value of X (atom ratio) as _1-X Fe _X , the CNR (signal-to-noise ratio) at 0.3 μm and the magnitude of the erasing magnetic field measured with an optical pickup using a semiconductor laser having a wavelength of 680 nm were measured. Is shown.

[0126]

[Table 6]

From Table 6, it can be seen that as the Fe content increases, that is, as X becomes larger than 0.10, the CNR gradually decreases.
R is also larger than that of Comparative Example 2, and the effect of forming the reflective layer 10 can be seen. On the other hand, as for the erasing magnetic field, when the reflective layer 10 made of pure Al is used, a large erasing magnetic field of 50 kA / m is required, whereas X is set to 0.02 or more and 0.5 or more.
By setting the value to 0 or less, it was possible to reduce the erasing magnetic field.

Next, Table 7 shows that the reflective layer 10 was formed to a thickness of 20 nm.
The CNR (signal-to-noise ratio) at 0.3 μm measured with an optical pickup using a semiconductor laser having a wavelength of 680 nm while changing the value of X (atom ratio) as Al _{1 -X} Ni _X of
And the magnitude of the erasing magnetic field.

[0129]

[Table 7]

From Table 7, it can be seen that, as with Fe,
By setting X to be 0.02 or more and 0.50 or less, it was possible to reduce the erasing magnetic field.

In addition to Fe and Ni, Co, Gd, Tb, D
By similarly including magnetic metals such as y and Nd in Al, the erasing magnetic field can be reduced.

(Embodiment 6) In this embodiment, a case where a different material is used as the reflection layer 10 in the specific example of Embodiment 4 will be described.

In the fifth embodiment, the result in which a magnetic metal element is contained in Al as the reflection layer 10 is described. However, in the present embodiment, the case where a non-magnetic metal element is contained in Al is described. This section describes the improvement of recording characteristics.

Table 8 shows that the reflective layer 10 was made of Al having a thickness of 20 nm.
By changing the value of X (atom ratio) as _1-X Ti _X , the CNR (signal-to-noise ratio) at 0.3 μm and the magnitude of the erasing magnetic field measured with an optical pickup using a semiconductor laser having a wavelength of 680 nm were measured. Is shown.

[0135]

[Table 8]

From Table 8, it can be seen that as the Ti content increases, that is, as X becomes larger than 0.10, the CNR gradually decreases.
R is also larger than that of Comparative Example 2, and the effect of forming the reflective layer 10 can be seen. On the other hand, when looking at the erasing magnetic field, when the reflective layer 10 made of pure Al is used, a large erasing magnetic field of 50 kA / m is required, whereas X is set to 0.02 or more and 0.9 or more.
By setting it to 8 or less, it was possible to reduce the erasing magnetic field.

[0137] Next, Table 9, as the reflective layer 10, which shows the erasing magnetic field reduction effect when the content of the non-magnetic elements other than Ti to Al, the reflective layer 10 Al _0.5 Z _0.5
When Z is a non-magnetic metal other than Ti, the CNR (signal-to-noise ratio) at 0.3 μm measured by an optical pickup using a semiconductor laser having a wavelength of 680 nm.
And the magnitude of the erasing magnetic field.

[0138]

[Table 9]

From Table 9, it is found that Z is a nonmagnetic metal T
In the case where a, Pt, Au, Cu, and Si were used, all of the CNRs were larger than those in Comparative Example 2, and the effect of forming the reflective layer 10 was observed. On the other hand, looking at the erasing magnetic field,
It was possible to reduce the erasing magnetic field in the same manner as in the case where Ti was contained in the steel.

In the first to sixth embodiments, the reproducing layer 1
Although a magnetic layer that is in an in-plane magnetization state at room temperature and becomes a perpendicular magnetization state at a high temperature state is used, at least a signal reproduction region (a region heated to a predetermined temperature (reproduction temperature) or more during reproduction) has a perpendicular magnetization state. Can be used.

In the first to sixth embodiments, the in-plane magnetization layer 3
However, instead of this layer, a magnetic layer (see Embodiments 11 to 15) which is in an in-plane magnetization state at room temperature and becomes a perpendicular magnetization state at high temperature instead of this layer, and the direction of the transition metal sublattice magnetization is a recording layer A perpendicular magnetic layer (see Embodiments 7 to 10) which faces in the same direction as that of the recording layer 4 and in which the sum of the transition metal sublattice magnetization and the rare earth metal sublattice magnetization is in the opposite direction to the recording layer 4 can be used. Further, the in-plane magnetization layer 3 of the first to sixth embodiments
The magnetic layer does not need to be adjacent to the recording layer 4 and may be magnetostatically coupled to the recording layer 4 (see Embodiments 16 and 17).

Embodiment 7 Hereinafter, this embodiment will be described in detail with reference to the drawings.

FIG. 6 shows the principle of the magnetic domain expansion reproduction operation of this embodiment.

In the present magneto-optical recording medium, the magnetic field generated from the recording layer in the low temperature region is canceled by the magnetic field in the opposite direction. For example, in the magnetic domain expansion reproduction magneto-optical recording medium shown in FIG. 6, a blocking layer 3 '(magnetic mask layer in the claims) made of an alloy of a rare earth metal and a transition metal is formed adjacent to the recording layer 4 and exchanged. Are combined. Blocking layer 3 '
At room temperature, the rare earth metal sublattice moment is larger than the transition metal sublattice moment (rare earth metal rich), and the recording layer 4 has a transition metal sublattice moment larger than the rare earth metal sublattice moment from room temperature to the Curie temperature (transition metal rich). ing.

In the present magneto-optical recording medium having such a configuration,
At room temperature, the recording layer 4 and the blocking layer 3 'are exchange-coupled and the transition metal sublattice moments are aligned, so that at room temperature, the total magnetization direction of the blocking layer 3' (the direction of the rare earth metal sublattice moment). And the total magnetization direction of the recording layer 4 (the direction of the transition metal sublattice moment) is opposite. In the magneto-optical recording medium of the present embodiment, the reproducing layer 1
The direction of the magnetic field that affects the magnetic field is determined by the overall magnetization direction of the recording layer 4 and the blocking layer 3 ′. Therefore,
By using the above-described blocking layer 3 ', the magnetic field from the recording layer 4 can be reduced by the magnetic field of the blocking layer 3' at least at room temperature. In short, the magnetic coupling between the recording layer 4 and the reproducing layer 1 can be suppressed.

Further, in a low-temperature region near room temperature, if the magnitude of the total magnetization of the blocking layer 3 ′ and the magnitude of the total magnetization of the recording layer 4 are substantially the same and balanced, the magnetic flux leaking to the reproducing layer 1 becomes almost zero. Can be desirable.

On the other hand, when the temperature rises from room temperature, the difference in the magnitude of the rare earth metal sublattice moment and the transition metal sublattice moment decreases in the blocking layer 3 ', and the total magnetization decreases. In No. 4, once the difference between the magnitude of the rare earth metal sublattice moment and the transition metal sublattice moment becomes large, the total magnetization increases. Therefore, due to heating during reproduction, the balance of the total magnetization between the recording layer 4 and the blocking layer 3 ′ cannot be maintained, and the reproduction layer 1 is affected by the magnetic field generated from the recording layer 4. Thereby, the magnetization of the recording layer 4 is transferred to the reproducing layer 1.

As described above, in the magneto-optical recording medium of the present embodiment, during reproduction, the magnetization of the low-temperature portion of the recording layer 4 is masked by the blocking layer 3 ', and the high-temperature portion (the central portion of the light beam spot) Only the magnetic flux from the recording layer 4 leaks, and the recording signal is transferred to the reproducing layer 1. For this reason, even when the interval between the recording bits is reduced and an adjacent recording bit enters the enlarged magnetic domain region of the reproducing layer 1, no magnetic field is generated from the adjacent recording bit. Since the direction is determined only by the recording bits of the central portion heated to a high temperature, good reproduction characteristics can be obtained.

When information is reproduced from this magneto-optical recording medium, once the magnetic domains formed in the reproducing layer 1 are erased, which leads to a smooth reproducing operation, the laser beam for reproduction is pulse-emitted. If this is done, the magnetic domains can be extinguished while the laser is quenched, and the medium temperature can be raised while the laser is emitting to transfer the recording magnetic domains of the recording layer to the reproducing layer for signal reproduction. As a result, the quality of the reproduced signal can be improved.

A specific example of the present embodiment will be described below with reference to FIG. Here, a case where a magneto-optical disk is applied as a magneto-optical recording medium will be described.

As shown in FIG. 7, the magneto-optical disk according to the present embodiment has a substrate 6, a transparent dielectric layer 7, a reproducing layer 1,
The non-magnetic intermediate layer 2, the shielding layer 3 ', the recording layer 4, the protective layer 8, and the overcoat layer 9 have a disk body laminated in this order.

In such a magneto-optical disk, a Curie temperature recording method is used as a recording method, and a light beam 5 emitted from a semiconductor laser is focused on the reproducing layer 1 by an objective lens, which is known as a polar Kerr effect. Information is recorded and reproduced by the magneto-optical effect. The polar Kerr effect is a phenomenon in which the direction of rotation of the plane of polarization of reflected light is reversed according to the direction of magnetization perpendicular to the incident surface.

The substrate 6 is made of, for example, a transparent substrate such as polycarbonate and is formed in a disk shape.

The transparent dielectric layer 7 is made of AlN, SiN, Al
It is desirable to be made of a material that does not contain oxygen such as SiN, and its film thickness needs to be set so as to realize a good interference effect on incident laser light and to increase the Kerr rotation angle of the medium. The wavelength of the reproduction light is λ, the transparent dielectric layer 7
Is n, the thickness of the transparent dielectric layer 7 is (λ
/ 4n). For example, when the wavelength of the laser light is 680 nm, the thickness of the transparent dielectric layer 7 is 30 n.
It may be set to about m to 100 nm.

The reproducing layer 1 is a magnetic film containing a rare earth transition metal alloy or a rare earth metal or a transition metal as a main component, and its magnetic properties are adjusted so that the coercive force becomes small near the reproducing temperature. Have been.

The non-magnetic intermediate layer 2 is made of AlN, SiN, Al
It is made of a dielectric material such as SiN or a non-magnetic metal alloy such as Al, Ti, Ta or the like, and has a thickness of 1 to 80 nm so that the reproducing layer 1 and the blocking layer 3 ′ and the recording layer 4 are magnetostatically coupled. Is set.

The blocking layer 3 'is a magnetic film made of a rare earth transition metal alloy. As described with reference to FIG. 6, the composition of the blocking layer 3 ′ is adjusted so that the rare earth metal sublattice moment is larger than the transition metal sublattice moment at room temperature, and the magnetic field generated from the recording layer 4 is masked at room temperature. The direction of the transition metal sublattice moment from room temperature to the Curie temperature always follows the direction of the transition metal sublattice moment of the recording layer 4 described later. That is, the composition is adjusted so as to be determined by the direction of the transition metal sublattice moment of the recording layer 4.

The recording layer 4 is made of a perpendicular magnetization film made of a rare earth transition metal alloy, and has a transition metal sublattice moment larger than the rare earth metal sublattice moment from room temperature to the Curie temperature, and its film thickness is set in the range of 20 to 80 nm. Have been. The area of the recording magnetic domain is set smaller than the area of the magnetic domain existing in the reproducing layer 1 during reproduction.

The protection layer 8 is made of AlN, SiN, AlSiN
And the like, or a nonmagnetic metal alloy such as Al, Ti, Ta, etc., formed for the purpose of preventing oxidation of the rare earth transition metal alloy used for the reproducing layer 1 and the recording layer 4. The thickness is set in the range of 5 nm to 60 nm.

The overcoat layer 9 is formed by applying an ultraviolet curable resin or a thermosetting resin by spin coating, and irradiating ultraviolet rays or heating.

Hereinafter, a specific example of the present embodiment will be described in the order of (1) a method of forming a magneto-optical disk, and (2) recording / reproducing characteristics.

(1) Method for Forming a Magneto-Optical Disk A method for forming a magneto-optical disk having the above configuration will be described.

First, an Al target, a GdFeCo alloy target, a GdDyFe alloy target, and a Gd
In a sputtering apparatus provided with a DyFeCo alloy target, a disc-shaped polycarbonate substrate 6 having pregrooves and prepits is placed on a substrate holder. 1 × 10 ^-6 Torr in the sputtering equipment
After evacuation to r, a mixed gas of argon and nitrogen was introduced, power was supplied to the Al target, and a gas pressure of 4 × 1
Under a condition of 0 ^-3 Torr, a transparent dielectric layer 7 of AlN was formed on the substrate 6 to a thickness of 80 nm.

Next, the inside of the sputtering apparatus is again set to 1 × 10 ^−6.
After evacuating to Torr, introducing argon gas,
Electric power is supplied to the GdFeCo alloy target, the gas pressure is set to 4 × 10 ⁻³ Torr, and G
A reproducing layer 1 made of d _0.30 (Fe _0.80 Co _0.20 ) _0.70 was formed with a thickness of 40 nm. The reproducing layer 1 had a property of being in an in-plane magnetization state at room temperature, and having a property of being a perpendicular magnetization state at a temperature of 120 ° C., its compensation temperature was 300 ° C., and its Curie temperature was 320 ° C.

Next, a mixed gas of argon and nitrogen was introduced, power was supplied to the Al target, and a gas pressure of 4 × 10
^Under the condition of ^-3 Torr, a nonmagnetic intermediate layer 2 of AlN was formed on the reproducing layer 1 to a thickness of 20 nm.

Next, the inside of the sputtering apparatus is again set to 1 × 10 ^−6.
After evacuating to Torr, introducing argon gas,
Electric power is supplied to the GdDyFe alloy target, the gas pressure is set to 4 × 10 ⁻³ Torr, and (G
d _0.50 Dy _0.50 ) _0.28 Fe _0.72 was formed to have a thickness of 30 nm. The blocking layer 3 'was a rare earth metal-rich perpendicular magnetization film having a Curie temperature of 140 ° C. and a room temperature to a Curie temperature.

Next, power is supplied to the GdDyFeCo alloy target, the gas pressure is set to 4 × 10 ⁻³ Torr, and (Gd _0.50 Dy _0.50 ) _0.23 (Fe _0.80
A recording layer 4 of Co _0.20 ) _0.77 was formed with a thickness of 40 nm. The Curie temperature of the recording layer 4 was 275 ° C.

Next, a mixed gas of argon and nitrogen was introduced, power was supplied to the Al target, and a gas pressure of 4 × 10
^Under the condition of ^-3 Torr, a protective layer 8 of AlN was formed on the recording layer 4 to a thickness of 20 nm.

Next, an ultraviolet curable resin was applied on the protective layer 8 by spin coating, and irradiated with ultraviolet rays to form an overcoat layer 9.

(2) Recording / Reproducing Characteristics FIG. 8 shows the mark length dependence of the CNR (signal to noise ratio) of the above disk measured by an optical pickup using a semiconductor laser having a wavelength of 680 nm.

For comparison, the mark length dependence of the CNR of a magnetic domain expanded reproduction magneto-optical disk having a configuration without the blocking layer 3 'is also shown in FIG. The results for the above-described magneto-optical disk will be described as Example 2. The medium of the magneto-optical disk having no blocking layer has the same configuration as that of the medium described in the present embodiment except that the blocking layer 3 'is removed. The mark length dependency of the CNR shown here indicates a signal-to-noise ratio when a recording magnetic domain having a length corresponding to the mark length is continuously formed at a recording magnetic domain pitch twice as long as the mark length. is there.

When the CNRs of both the mark lengths of 0.3 μm are compared, the CNR of the comparative example 1 is 34.0 dB, whereas the CNR of the present embodiment 2 is 41.5 dB and 7.5 dB.
An increase has been observed. This is due to the fact that adjacent bits are masked by the blocking layer 3 ′ and the reproduction resolution is increased.

The recording / reproducing characteristics when the conditions of each layer in Example 2 are changed are shown below.

(A) Film thickness of reproducing layer 1 and blocking layer 3 'Next, Table 10 shows that the CNR at 0.3 μm was changed by changing the film thickness of the reproducing layer 1 and the blocking layer 3' in Example 2. It shows the result of the measurement.

[0175]

[Table 10]

In Table 10, the thickness of the blocking layer of 0 nm indicates the result of Comparative Example 1 in which the blocking layer 3 'was not formed. When the film thickness of the blocking layer 3 'is 10 nm or more, a mask effect appears and the CNR increases, but when the film thickness exceeds 60 nm, the CNR decreases. It is considered that this is because the leakage magnetic field in the high-temperature portion decreases, and the magnetic domain transfer from the recording layer 4 hardly occurs. As described above, the film thickness of the barrier layer 3 ′ that can obtain a higher CNR than that of Comparative Example 1 is 10 to 60 nm.
It turns out that it is the range of.

When the thickness of the reproducing layer 1 is set to 8 nm,
The reproduced signal becomes smaller, and its CNR becomes lower than that of Comparative Example 1. Further, the thickness of the reproducing layer 1 is set to 100 nm.
In this case, magnetic domain expansion transfer becomes difficult, and the CNR thereof is lower than that of Comparative Example 1. From the above, the thickness of the reproducing layer 1 from which the CNR is higher than that of the comparative example 1 is:
It turns out that it is the range of 10-80 nm.

(B) Film thickness of nonmagnetic intermediate layer 2 Next, Table 11 shows the results of measuring the CNR at 0.3 μm by changing the film thickness of the nonmagnetic intermediate layer 2 in Example 2. It is.

[0179]

[Table 11]

As can be seen from Table 11, the non-magnetic intermediate layer 2
It can be seen that when the film thickness is 0.5 nm, the CNR is significantly reduced. This is presumably because the nonmagnetic intermediate layer 2 was too thin to obtain a good magnetostatic coupling state. The thickness of the nonmagnetic intermediate layer 2 is 1 nm
In this case, the maximum CNR is obtained, and as the film thickness of the nonmagnetic intermediate layer 2 increases, the magnetostatic coupling force decreases and the CNR decreases. In order to obtain a higher CNR than that of Comparative Example 1, the thickness of the nonmagnetic intermediate layer 2 is set to 1 to
It can be seen that it is necessary to set the range to 80 nm.

Further, it can be seen that by increasing the thickness of the non-magnetic intermediate layer 2, the magnetostatic coupling force between the reproducing layer 1 and the recording layer 4 is reduced, and the erasing magnetic field is reduced. In order to keep the erasing magnetic field within a practical range of 31 kA / m or less, it is desirable that the thickness of the nonmagnetic intermediate layer 2 be 4 nm or more.

(C) Curie temperature of the barrier layer 3 'In the above, the Curie temperature of the barrier layer 3' is 14
The recording / reproducing characteristics when (Gd _0.50 Dy _0.50 ) _0.28 Fe _0.72 at 0 ° C. is used are described. Next, the results of investigating the recording / reproducing characteristics by changing the Gd content of the blocking layer 3 ′ will be described.

Table 12 shows that, when the barrier layer 3 'is (Gd _x Dy _{1 -x} ) _0.28 Fe _0.72 having a thickness of 30 nm, X (atom)
Ratio), the Curie temperature T _C3 of the barrier layer 3 ′,
It shows the result of measuring the CNR (signal-to-noise ratio) at 0.3 μm measured by an optical pickup using a semiconductor laser having a wavelength of 680 nm.

[0184]

[Table 12]

In Table 12, the CNR (34.0 dB) obtained in Comparative Example 1 in which the blocking layer 3 'was not formed.
CNR higher than 0.20 ≦ X ≦ 1.0
It can be seen that the range is 0.

The recording layer 4 used in Table 12 was 1
At a temperature of 40 ° C. (heating temperature during reproduction), the magnitude of magnetization becomes maximum. That is, it is sufficient that the blocking layer 3 ′ can mask the leakage magnetic field from the recording layer at a temperature of 140 ° C. or less, and the optimal value of the Curie temperature of the blocking layer 3 ′ is about 1
40 ° C. (near the heating temperature during regeneration). However, as shown in Table 12, when the Curie temperature of the barrier layer 3 ′ is 80 ° C. or more and 220 ° C. or less,
A CNR higher than that of Comparative Example 1 was obtained, and the barrier layer 3 ′ was obtained.
By setting the Curie temperature of not less than 80 ° C. and not more than 220 ° C., it is possible to obtain a low-temperature mask effect.

In this case, Gd is used as the barrier layer 3 '.
Although the results using DyFe are described, it is only necessary to satisfy the Curie temperature range (80 ° C. to 220 ° C.). In addition, a GdDyFe alloy, a TbFe alloy, a DyFe
Alloy, GdFe alloy, GdTbFe alloy, DyFeCo
It is possible to use a perpendicular magnetization film made of an alloy containing either an alloy or a TbFeCo alloy.

(D) Compensation temperature of blocking layer 3 'In the above, the Curie temperature of the blocking layer 3' is 80 ° C.
Although it was explained that a temperature of ~ 220 ° C is desirable,
Even when the compensation temperature is 80 ° C. to 220 ° C., the effect of the present embodiment is similarly obtained (interruption of the magnetic field from the recording layer 4 at room temperature).
Can be obtained. Hereinafter, this specific example will be described.

As a barrier layer 3 ', a (Gd
_{Using 0.8} Dy _0.2 ) _0.26 Fe _0.74 , the CNR (signal-to-noise ratio) at 0.3 nm was measured by an optical pickup using a semiconductor laser having a wavelength of 680 nm. In addition, the blocking layer 3 ′
Has a compensation temperature of 140 ° C. and a Curie temperature of 200 ° C.

In this case, the CNR was 41.5 dB, and almost the same characteristics as in the case of the second embodiment were obtained. That is, even when the blocking layer 3 ′ has a compensation temperature, a masking effect of the leakage magnetic field from the recording layer 4 can be obtained. The compensation temperature is desirably set to 140 ° C. (near the heating temperature at the time of reproduction) at which the magnetization of the recording layer is maximized, but otherwise, if the compensation temperature is in the temperature range of 80 ° C. to 220 ° C. or less, the mask effect It is possible to obtain If the compensation temperature is 80 ° C. to 220 ° C., in addition to GdDyFe, a GdDyFe alloy, a TbFe alloy, a DyFe alloy,
GdFe alloy, GdTbFe alloy, DyFeCo alloy,
A perpendicular magnetization film made of an alloy containing any of the TbFeCo alloys can be used.

(Embodiment 8) Embodiment 8 of the present invention is described below with reference to FIG. In the present embodiment, a case where a magneto-optical disk is applied as a magneto-optical recording medium will be described.

The magneto-optical disk according to the eighth embodiment includes:
As shown in FIG. 9, a substrate 6, a transparent dielectric layer 7, a reproducing layer 1, a nonmagnetic intermediate layer 2, a recording layer 4, a blocking layer 3 ', a protective layer 8, and an overcoat layer 9 are laminated in this order. Disk body.

The magneto-optical disk of the eighth embodiment is the same as the magneto-optical disk of the seventh embodiment, except that the shielding layer 3 '
And the recording layer 4 is formed in a reverse order.

Hereinafter, specific examples of the present embodiment will be described in the order of (1) a method of forming a magneto-optical disk, and (2) recording / reproducing characteristics.

(1) Method of Forming Magneto-Optical Disk The magneto-optical disk of the present embodiment differs from the method of forming a magneto-optical disk of Embodiment 7 in that the order of forming the blocking layer 3 'and the recording layer 4 is reversed. The substrate 6, the transparent dielectric layer 7, the reproducing layer 1, the nonmagnetic intermediate layer 2, the protective layer 8, and the overcoat layer 9 were formed in the same manner as in Example 2.

(2) Recording / Reproducing Characteristics Table 13 shows the reproducing layer 1 and the blocking layer 3 'in the present embodiment.
3 shows the CNR (signal-to-noise ratio) at 0.3 μm measured by an optical pickup using a semiconductor laser having a wavelength of 680 nm while changing the film thickness of the semiconductor laser.

[0197]

[Table 13]

In Table 13, the thickness of the blocking layer of 0 nm indicates the result of Comparative Example 1 in which the blocking layer 3 'was not formed. Further, a third embodiment is described in which the recording layer 4 and the blocking layer 3 ′ in the second embodiment described in the seventh embodiment are simply replaced.

When the thickness of the blocking layer 3 'is 10 nm or more, a mask effect appears and the CNR increases.
When it exceeds m, the CNR decreases. This is presumably because the effect of the mask is reduced and is affected by adjacent recording signals. From the above, it can be seen that the film thickness of the blocking layer 3 ′ from which the CNR is higher than that of Comparative Example 1 is in the range of 10 to 80 nm.

Further, as compared with the case of the seventh embodiment, since the blocking layer exists on the side opposite to the incidence of the light beam 5, the effect of the mask is weakened and the CNR is relatively reduced. The barrier layer 3 'required to realize a higher CNR
Has a wide range of film thickness.

Incidentally, (a) the thickness of the reproducing layer 1, (b) the thickness of the nonmagnetic intermediate layer 2, (c) the Curie temperature of the blocking layer 3 ',
(D) Embodiment 7 Regarding Compensation Temperature of Blocking Layer 3 ′
And the same results as those shown in FIG.

(Embodiment 9) Embodiment 9 of the present invention will be described below with reference to FIG.
In the present embodiment, a case where a magneto-optical disk is applied as a magneto-optical recording medium will be described.

The magneto-optical disk according to the ninth embodiment is
As shown in FIG. 10, the substrate 6, the transparent dielectric layer 7, the reproducing layer 1, the nonmagnetic intermediate layer 2, the reflective layer 10, the blocking layer 3 ', the recording layer 4, the protective layer 8, and the overcoat layer 9 are It has disk bodies stacked in sequence.

In Embodiments 7 and 8, when the thickness of the reproducing layer 1 is smaller than 40 nm,
The light beam 5 transmitted through the reproducing layer 1 is reflected by the blocking layer 3 'or the recording layer 4, and the information of the recording bit signal adjacent to the recording layer 4 is mixed into the reproduction signal, so that the reproduction signal characteristics deteriorate. Is the result.

The magneto-optical disk according to the ninth embodiment has the same configuration as the magneto-optical disk according to the seventh embodiment except that a reflection layer 10 is formed between the nonmagnetic intermediate layer 2 and the blocking layer 3 '. Have. By doing so, the reproduction layer 1
The light beam 5 transmitted through the reproducing layer 1 is reflected by the reflecting layer 10 even when the film thickness of the recording layer becomes as thin as 40 nm or less, thereby preventing the information of the adjacent recording bit signal of the recording layer 4 from being mixed into the reproduced signal. Thus, magnetic domain expansion reproduction by the reproduction layer 1 can be more complete.

Hereinafter, specific examples of the magneto-optical disk of the present embodiment will be described.
(2) The recording and reproducing characteristics will be described separately.

(1) Method of Forming Magneto-Optical Disk The magneto-optical disk of the present embodiment differs from the method of forming a magneto-optical disk of Embodiment 7 in that the non-magnetic intermediate layer 2 and the blocking layer 3 ' , Al, a reflective layer 10, a substrate 6, a transparent dielectric layer 7, a reproducing layer 1, a nonmagnetic intermediate layer 2, a blocking layer 3 ′, a recording layer 4, a protective layer 8, and an overcoat layer 9. In the same manner as in Example 2, the reproducing layer 1 was formed with a thickness of 25 nm.

Here, after forming the nonmagnetic intermediate layer 2, the Al reflecting layer 10 was again exposed to 1 × 10 ⁻⁶ T in the sputtering apparatus.
after evacuating to orr and introducing argon gas, A
l Supply power to the target and set the gas pressure to 4 × 10 ^-3 To
rr, a reflective layer 10 made of Al was formed on the nonmagnetic intermediate layer 2 with a thickness of 2 to 80 nm.

(2) Recording / Reproducing Characteristics Table 14 shows that the CNR (at 0.3 μm) measured with an optical pickup using a semiconductor laser having a wavelength of 680 nm by changing the thickness of the reflective layer 10 of the present embodiment. (Signal-to-noise ratio).

[0210]

[Table 14]

In Table 14, the thickness of the reflective layer of 0 nm indicates the result of Comparative Example 3 in which the reflective layer 10 was not formed. Even when the thickness of the reflective layer 10 is extremely thin, such as 2 nm, the effect of blocking information reproduction from the recording layer 4 is seen, and the CNR increases by 0.5 dB. By increasing the thickness of the reflective layer 10, the CNR gradually increases, and the CNR becomes maximum at the thickness of 20 nm. This is because the effect of blocking information reproduction from the recording layer 4 becomes more remarkable as the thickness of the reflective layer increases. Although the CNR is reduced at the film thickness of 20 nm or more, the magnetostatic coupling force acting between the recording layer 4 and the reproducing layer 1 is weakened by increasing the distance between them. From the above, in order to obtain a higher CNR than that of Comparative Example 3, the thickness of the reflective layer 10 is set to 2 to 4
It can be seen that it is necessary to set within the range of 0 nm.

In the above description, the reflection layer 10 is
Although the reproduction characteristics using Al are described, an alloy of Al and a metal other than Al may be used as the reflective layer 10.

Table 15 shows that the reflective layer 10 was formed of a 20 nm thick A
By changing the value of X (atom ratio) as l _1-x Fe _x , the CNR (signal-to-noise ratio) at 0.3 μm and the magnitude of the erasing magnetic field measured by an optical pickup using a semiconductor laser having a wavelength of 680 nm. Is shown.

[0214]

[Table 15]

From Table 15, it can be seen that as the Fe content increases, that is, as X becomes larger than 0.10, the CNR gradually decreases.
The NR is also larger than that of Comparative Example 3 described above, and the effect of forming the reflective layer 10 is seen. On the other hand, as for the erasing magnetic field, when the reflective layer 10 made of pure Al is used, a large erasing magnetic field of 50 kA / m is required, whereas X is set to 0.02.
By setting the value to 0.50 or less, it was possible to reduce the erasing magnetic field.

Next, Table 16 shows that the reflective layer 10 was formed to a film thickness of 20 n.
The CNR (signal-to-noise ratio) at 0.3 μm measured by an optical pickup using a semiconductor laser having a wavelength of 680 nm while changing the value of X (atom ratio) as Al _1-x Ni _x of m
And the magnitude of the erasing magnetic field.

[0219]

[Table 16]

From Table 16, it was found that the erasing magnetic field could be reduced by setting X to be 0.02 or more and 0.50 or less as in the case where Fe was contained.

In addition to Fe and Ni, Co, Gd, Tb, D
By similarly including magnetic metals such as y and Nd in Al, the erasing magnetic field can be reduced.

Next, a description will be given of an improvement in recording characteristics when a non-magnetic metal element is contained in Al as the reflective layer 10.

Table 17 shows that the reflective layer 10 was made of A having a thickness of 20 nm.
By changing the value of X (atom ratio) as l _1-x Ti _X , the CNR (signal-to-noise ratio) at 0.3 μm and the magnitude of the erasing magnetic field were measured with an optical pickup using a semiconductor laser having a wavelength of 680 nm. Is shown.

[0222]

[Table 17]

From Table 17, it can be seen that as the Ti content increases, that is, as X becomes greater than 0.10, the CNR gradually decreases.
The NR is also larger than that of Comparative Example 3, and the effect of forming the reflective layer 10 can be seen. On the other hand, when looking at the erasing magnetic field, when the reflective layer 10 made of pure Al is used, a large erasing magnetic field of 50 kA / m is required, whereas X is set to 0.02 or more and 0.2 to 0.2.
By setting it to 98 or less, it was possible to reduce the erasing magnetic field.

Next, Table 18 shows that the reflective layer 10 is made of Ti
The non-magnetic elements other than are those showing the erasing magnetic field reduction effect when the content of the Al, a reflective layer 10 Al _0.5 Z
_{When 0.5 is used} as the Z value, the CNR (signal-to-noise ratio) at 0.3 μm and the magnitude of the erasing magnetic field measured by an optical pickup using a semiconductor laser having a wavelength of 680 nm when Z is a nonmagnetic metal other than Ti are shown. ing.

[0225]

[Table 18]

From Table 18, it is found that Z is a nonmagnetic metal T
When a, Pt, Au, Cu, and Si were used, all of the CNRs were larger than those of Comparative Example 3 described above, and the reflection layer 1
The effect of forming 0 is seen. On the other hand, as for the erasing magnetic field, it was possible to reduce the erasing magnetic field as in the case where Ti was contained in Al.

Although the case where the reflection layer is applied to the magneto-optical disk described in the seventh embodiment has been described here, it goes without saying that the same result can be obtained by applying the eighth embodiment to the magneto-optical disk.

Incidentally, (a) the thicknesses of the reproducing layer and the blocking layer, and (c)
With respect to the Curie temperature of the blocking layer 3 'and (d) the compensation temperature of the blocking layer 3', the same results as those shown in the seventh and eighth embodiments were obtained.

(Embodiment 10) Embodiment 1 of the present invention
0 will be described below with reference to FIG. In the present embodiment, a case where a magneto-optical disk is applied as a magneto-optical recording medium will be described.

As shown in FIG. 11, the magneto-optical disk according to the tenth embodiment includes a substrate 6, a transparent dielectric layer 7, a reproducing layer 1, a non-magnetic intermediate layer 2, a blocking layer 3 ', a recording layer 4, The protective layer 8, the heat radiation layer 110, and the overcoat layer 9 have a disk body laminated in this order.

The magneto-optical disk of the tenth embodiment is the same as the magneto-optical disk of the seventh embodiment except that
The heat radiation layer 110 is formed between the heat dissipation layer 110 and the overcoat layer 9.

The following describes (1) a method for forming a magneto-optical disk and (2) recording / reproducing characteristics for a specific example of the present embodiment.

(1) Method of Forming Magneto-Optical Disk The magneto-optical disk of this embodiment is the same as the method of forming a magneto-optical disk described in Example 2 except that Al is formed between the protective layer 8 and the overcoat layer 9. The substrate 6, the transparent dielectric layer 7, the reproducing layer 1, the non-magnetic intermediate layer 2, the blocking layer 3 ', the recording layer 4, the protective layer 8, and the overcoat layer 9 are formed as follows. Similarly to the method described in Embodiment 7, the protective layer 8 was formed with a thickness of 5 nm.

Here, the heat dissipation layer 110 of Al is
Is formed, the inside of the sputtering apparatus is again set to 1 × 10 ⁻⁶ To.
After evacuating to rr, argon gas was introduced and Al
Power is supplied to the target and the gas pressure is 4 × 10 ⁻³ Torr
and a heat radiation layer 110 made of Al on the recording layer 4.
Was formed with a film thickness of 20 nm.

(2) Recording / reproducing characteristics The CNR (signal-to-noise ratio) at 0.3 μm was measured with an optical pickup using a semiconductor laser having a wavelength of 680 nm. As a result, the CNR was 42.5 dB, as compared with the case of the second embodiment. Further, it was improved by 1 dB.

As in this embodiment, A having a high thermal conductivity
If there is a heat dissipation layer 110 made of l, the spread of heat in the lateral direction can be released in the heat dissipation layer side, that is, in the thickness direction of the layer,
The spread of heat in the lateral direction can be reduced. Therefore, the temperature distribution in the light beam becomes steeper, and the effect of masking the magnetic field from the recording layer in the reproducing layer by the blocking layer can be enhanced, and the reproducing characteristics can be further improved.

Al, which is a material of the heat radiation layer 110, has a higher thermal conductivity than the rare earth transition metal alloy film used for the reproducing layer 2 and the recording layer 4, and is a material suitable for the heat radiation layer. It is also a very cheap material.

The material of the heat radiation layer 110 is the same as that of the above-described example.
In addition to l, any material having a higher thermal conductivity than the reproducing layer and the recording layer, such as Au, Ag, Cu, SUS, Ta, and Cr, may be used.

When Au is used, it has excellent oxidation resistance, moisture resistance, and pitting resistance, so that long-term reliability can be improved.

When Ag is used, it has excellent oxidation resistance, moisture resistance, and pitting corrosion resistance, so that long-term reliability can be improved.

When Cu is used, it has excellent oxidation resistance, moisture resistance, and pitting resistance, so that long-term reliability can be improved.

If SUS, Ta, or Cr is used, these materials are extremely excellent in oxidation resistance, moisture resistance, and pitting resistance, so that it is possible to provide a magneto-optical disk with more excellent long-term reliability. it can.

Although the thickness of the heat radiation layer 10 is set to 20 nm in this embodiment, the heat radiation effect increases as the thickness increases, and the long-term reliability also increases. However, since it also affects the recording sensitivity of the magneto-optical disk, it is necessary to set the film thickness in accordance with the thermal conductivity and specific heat of the material.
A range of 200 nm is good. In particular, 10-100 nm
Is preferred. If the material has relatively high thermal conductivity and excellent corrosion resistance, the film thickness can be as thin as about 10 to 100 nm, and the time required for film formation can be shortened.

Although the case where the radiation layer is applied to the magneto-optical disk described in the seventh embodiment has been described here, the first to sixth, eighth, and ninth embodiments and the later-described embodiments 11 to 15 will be described. It goes without saying that a similar result can be obtained by applying the same.

In the tenth embodiment, (a) the thickness of the reproducing layer 1 and the blocking layer 3 ′, (b) the thickness of the nonmagnetic intermediate layer 2,
Regarding (c) the Curie temperature of the blocking layer 3 ′, (d) the compensation temperature of the blocking layer 3 ′, (e) the thickness of the reflective layer, and the material, the same results as those described in Embodiments 7 to 9 were obtained. Obtained.

In Embodiments 7 to 10 described above,
A magnetic layer that has an in-plane magnetization state at room temperature and a perpendicular magnetization state at a high temperature is used as a reproduction layer, but has a perpendicular magnetization state at least in a signal reproduction region (a region heated to a predetermined temperature or higher during reproduction). Can be used.

Embodiment 11 Hereinafter, Embodiment 11 of the present invention will be described in detail with reference to the drawings.

FIG. 12 shows the principle of magnetic domain expansion reproduction of this embodiment.

In the magneto-optical recording medium of the present embodiment, a transfer layer 3 ″ (magnetic mask layer in the claims) that is magnetostatically coupled to the reproduction layer 1 is provided between the reproduction layer 1 and the recording layer 4. The transfer layer 3 ″ exhibits in-plane magnetization at room temperature and perpendicular magnetization at a predetermined temperature or higher. Then, the transfer layer 3 "masks the magnetization of the portion 11 of the recording layer 4 that is not heated to a temperature equal to or higher than the predetermined temperature (hereinafter, referred to as a critical temperature). The transmission of the magnetization from the portion 11 to the reproducing layer 1 is prevented.

On the other hand, in the portion above the critical temperature, the transfer layer 3 ″
Indicates perpendicular magnetization, so that it is possible to remove the mask, and it is possible to reproduce information only in the range above the target critical temperature of the recording layer 4.

Therefore, the heating temperature of the transfer layer 3 ″ during reproduction is set such that only the magnetic flux from one recording bit in the recording layer 4 is leaked by the transfer layer 3 ″ and the magnetic flux from the other recording bits is masked. Is set, the effect of the adjacent bits 11 is suppressed even if the interval between the recording bits is narrowed, so that only information of one recording bit can be transferred to the reproducing layer 1, and good reproduction characteristics can be obtained. Can be.

Here, the transfer layer 3 ″ needs to have a Curie temperature above the critical temperature in order to effectively work the magnetostatic coupling between the recording layer 4 and the reproducing layer 1 in the range above the critical temperature. Further, by setting the temperature lower than the Curie temperature of the recording layer 4, there is no magnetic influence at the time of recording, so that stable recording can be performed.

When the reproducing layer 1 is reproduced by a laser beam, it is preferable that the size of the magnetic domain is large because the signal amount increases and the cause of noise is reduced. In addition, the domain wall needs to move in accordance with the magnetic field from the recording layer 4, and a characteristic having a small coercive force is advantageous.

When information is reproduced from the magneto-optical recording medium, once the magnetic domains formed in the reproducing layer 1 are erased, which leads to a smooth reproducing operation, the reproducing laser beam is pulsed. It is desirable to emit light. In this way, the magnetic domains are extinguished while the laser is extinguished, and the medium temperature is increased while the laser is emitting light, so that the recording magnetic domains of the recording layer 4 are transferred to the reproducing layer 1 and the signal is reproduced. Can be performed, and the quality of the reproduced signal can be made higher.

A specific example of the present embodiment will be described below with reference to FIG. Here, a case where a magneto-optical disk is applied as a magneto-optical recording medium will be described.

As shown in FIG. 13, the magneto-optical disk according to this embodiment has a substrate 6, a transparent dielectric layer 7, a reproducing layer 1, a non-magnetic intermediate layer 2, a transfer layer 3 ″, a recording layer 4, a protective layer The layer 8 and the overcoat layer 9 have a disk body laminated in this order.

In such a magneto-optical disk, a Curie temperature recording method is used as a recording method, and a light beam 5 emitted from a semiconductor laser is focused on the reproducing layer 1 by an objective lens, and is known as a polar Kerr effect. Information is recorded and reproduced by the magneto-optical effect. The polar Kerr effect is a phenomenon in which the direction of rotation of the polarization plane of reflected light is rotated by magnetization perpendicular to the incident surface.
This is a phenomenon in which the direction of rotation changes depending on the direction of magnetization.

The substrate 6 is made of a transparent base material such as polycarbonate, and is formed in a disk shape.

The transparent dielectric layer 7 is made of AlN, SiN, Al
It is desirable to use a material having a large refractive index such as SiN or TiO ₂ , and the film thickness is set so as to realize a good interference effect on the incident laser light and to increase the Kerr rotation angle of the medium. When the wavelength of the reproduction light is λ and the refractive index of the transparent dielectric layer 7 is n, the thickness of the transparent dielectric layer 7 is set to about (λ / 4n). For example, when the wavelength of the laser light is 680 nm, the thickness of the transparent dielectric layer 7 may be set to about 30 nm to 100 nm.

The reproducing layer 1 is a magnetic film made of a rare earth transition metal alloy, and its magnetic properties are in an in-plane magnetization state at room temperature, approach a compensation composition as the temperature rises, and the total magnetization becomes smaller. The composition is adjusted so that the effect of the magnetic field is weakened and a perpendicular magnetization state is obtained.

The non-magnetic intermediate layer 2 is made of AlN, SiN, Al
It consists of one layer of a dielectric such as SiN, one layer of a non-magnetic metal alloy such as Al, Ti, Ta, or two layers of a dielectric and a metal, and the reproducing layer 1 and the recording layer 4 are magnetostatically coupled. It is set to be.

The transfer layer 3 ″ is a rare earth transition metal alloy or a magnetic film containing a rare earth metal or a transition metal as a main component, exhibits in-plane magnetization at room temperature, and exhibits perpendicularity at a predetermined temperature (critical temperature) or higher. As shown in FIG. 12, the transfer layer 3 ″ masks the magnetic field generated from the perpendicular magnetization of the recording layer 4 with the in-plane magnetization at a temperature equal to or lower than the critical temperature, so that the transfer layer 3 ″ Prevent magnetic fields. At a temperature higher than the critical temperature, the composition is adjusted so that the mask effect is lost due to the perpendicular magnetization, and the magnetic field generated from the recording layer 4 is easily transmitted to the reproducing layer.

The recording layer 4 is made of a perpendicular magnetization film made of a rare earth transition metal alloy, and its thickness is set in the range of 20 to 80 nm.

The protection layer 8 is made of AlN, SiN, AlSi
It is made of a dielectric material such as N or SiC or a non-magnetic metal alloy such as Al, Ti or Ta, and is formed for the purpose of preventing the rare earth transition metal alloy used for the reproducing layer 1 and the recording layer 4 from being oxidized. And its film thickness is set in the range of 5 nm to 60 nm.

The overcoat layer 9 is formed by applying an ultraviolet curable resin or a thermosetting resin by spin coating, and irradiating ultraviolet rays or heating.

Hereinafter, a specific example of the magneto-optical disk of the present embodiment will be described with respect to (1) a forming method and (2) recording / reproducing characteristics.

(1) Forming Method A method of forming a magneto-optical disk having the above configuration will be described.

First, in a sputtering apparatus provided with an Al target, two types of GdFeCo alloy targets corresponding to the reproducing layer 1 and the transfer layer 3 ″, and a GdDyFeCo alloy target, a disc-shaped disk having pre-grooves and pre-pits was provided. Polycarbonate substrate 6 formed on
Is placed on the substrate holder. 1 × 10 inside the sputtering equipment
After evacuation to ^-6 Torr, a mixed gas of argon and nitrogen was introduced, power was supplied to the Al target, and a transparent dielectric layer made of AlN was formed on the substrate 6 under the conditions of a gas pressure of 4 × 10 ^-3 Torr. 7 was formed with a thickness of 80 nm.

Next, the inside of the sputtering apparatus is again set to 1 × 10 ^−6.
After evacuating to Torr, introducing argon gas,
Electric power is supplied to the GdFeCo alloy target, the gas pressure is set to 4 × 10 ⁻³ Torr, and G
A reproducing layer 1 made of d _0.30 (Fe _0.80 Co _0.20 ) _0.70 was formed with a thickness of 40 nm.

The reproducing layer 1 has a property of being in an in-plane magnetization state at room temperature, and having a property of being in a perpendicular magnetization state at a temperature of 120 ° C. The compensation temperature is 300 ° C., and the Curie temperature is 3
20 ° C.

Next, a mixed gas of argon and nitrogen was introduced, power was supplied to the Al target, and a gas pressure of 4 × 10
^Under the condition of ^-3 Torr, a nonmagnetic intermediate layer 2 of AlN was formed on the reproducing layer 1 to a thickness of 20 nm.

Next, power is supplied to the GdFeCo alloy target, the gas pressure is set to 4 × 10 ⁻³ Torr, and the transfer layer 3 ″ made of Gd _0.30 (Fe _0.85 Co _0.15 ) _{0.70 is formed} on the nonmagnetic intermediate layer 2. The transfer layer 3 ″ is in an in-plane magnetization state at room temperature and has a thickness of 120 ° C.
, And had a Curie temperature of 250 ° C.

Next, the inside of the sputtering apparatus is again set to 1 × 10 ^−6.
After evacuating to Torr, introducing argon gas,
A power is supplied to the GdDyFeCo alloy target, the gas pressure is set to 4 × 10 ⁻³ Torr, and on the transfer layer 3 ″,
A recording layer 4 of (Gd _0.50 Dy _0.50 ) _0.23 (Fe _0.80 Co _0.20 ) _0.77 was formed with a thickness of 40 nm. The recording layer 4 has a compensation temperature of 25 ° C. and a Curie temperature of 275.
° C.

Next, a mixed gas of argon and nitrogen was introduced, power was supplied to the Al target, and a gas pressure of 4 × 10
^Under the condition of ^-3 Torr, a protective layer 8 of AlN was formed on the recording layer 4 to a thickness of 20 nm.

Next, an ultraviolet curable resin was applied on the protective layer 8 by spin coating, and irradiated with ultraviolet rays to form an overcoat layer 9.

(2) Recording / Reproducing Characteristics FIG. 14 shows the mark length dependence of the CNR (signal to noise ratio) of the above disk measured by an optical pickup using a semiconductor laser having a wavelength of 680 nm. In this figure, the above-described magneto-optical disk of the present embodiment is shown as Example 4.

For comparison, the mark length dependence of the CNR of a magneto-optical disk having a structure without the transfer layer 3 ″ is also shown in FIG. The disk medium has a configuration in which the transfer layer 3 ″ is removed from the medium configuration described in the present embodiment. The mark length dependency of the CNR indicates that a recording magnetic domain having a length corresponding to the mark length is marked. It shows the signal-to-noise ratio when the recording magnetic domain pitch is twice as long as the recording magnetic domain pitch.

Comparing the CNRs of both of the mark lengths of 0.3 μm, the CNR of Comparative Example 1 is 34.0 dB, whereas the CNR of Example 4 is 41.0 dB and 7.0 dB.
An increase has been observed. This is due to the fact that the transfer layer 3 ″ makes the magnetization mask for the recording layer 4 effective and the reproduction resolution is increased.

Next, Table 19 shows that the film thickness of the reproducing layer 1 and the transfer layer 3 ″ in Example 4 was changed and the C at 0.3 μm was changed.
It shows the result of measuring NR.

[0280]

[Table 19]

In Table 19, the transfer layer thickness of 0 nm shows the result of Comparative Example 1 in which the transfer layer 3 ″ was not formed. Even when the thickness of the transfer layer 3 ″ was extremely thin, 2 nm. By realizing the strengthening of the in-plane magnetization mask, the CNR increases by 1.5 dB. As for the thickness of the transfer layer 3 ″, the CNR increases by realizing the strengthening of the in-plane magnetization mask up to 30 nm, but the CNR decreases when the thickness is further increased. And the in-plane magnetization mask is strengthened too much,
It is considered that this is due to the fact that the magnetic aperture becomes difficult to open, so that a perfect perpendicular magnetization state of the reproducing layer cannot be obtained. Here, from Table 19, it can be seen that the film thickness of the transfer layer 3 ″ in which the CNR is higher than that of Comparative Example 1 is in the range of 2 to 40 nm.

When the thickness of the reproducing layer 1 is set to 8 nm,
The reproduced signal becomes smaller, and its CNR becomes lower than that of Comparative Example 1. Further, the thickness of the reproducing layer 1 is set to 120 nm.
In this case, the domain wall energy generated in the reproducing layer 1 increases, and a complete perpendicular magnetization state cannot be obtained in a portion where the temperature is increased, and its CNR becomes lower than that in Comparative Example 1. From Table 19, it can be seen that the thickness of the reproducing layer 1 having a higher CNR than that of Comparative Example 1 is in the range of 10 to 80 nm.

Next, Table 20 shows the results of measuring the CNR at 0.3 μm and the magnetic field necessary for erasing (erasing magnetic field) by changing the thickness of the nonmagnetic intermediate layer 2 in Example 4. Things.

[0284]

[Table 20]

As can be seen from Table 20, the nonmagnetic intermediate layer 2
It can be seen that when the film thickness is 0.5 nm, the CNR is significantly reduced. This is presumably because the nonmagnetic intermediate layer 2 was too thin to obtain a good magnetostatic coupling state. The thickness of the nonmagnetic intermediate layer 2 is 1 nm
In this case, the maximum CNR is obtained, and as the film thickness of the nonmagnetic intermediate layer 2 increases, the magnetostatic coupling force decreases and the CNR decreases. In order to obtain a higher CNR than that of Comparative Example 1, the thickness of the nonmagnetic intermediate layer 2 is set to 1 to
It can be seen that it is necessary to set the range to 80 nm.

Further, it can be seen that by increasing the thickness of the non-magnetic intermediate layer 2, the magnetostatic coupling force between the reproducing layer 1 and the recording layer 4 is reduced, and the erasing magnetic field is reduced. In order to keep the erasing magnetic field within a practical range of 31 kA / m or less, it is desirable that the thickness of the nonmagnetic intermediate layer 2 be 4 nm or more.

(Embodiment 12) In this embodiment, an example in which a transfer layer 3 "having a different composition is used in the specific example of the magneto-optical disk shown in Embodiment 11 will be described.

In the eleventh embodiment, the temperature at which the transfer layer 3 ″ shifts from in-plane magnetization to perpendicular magnetization (hereinafter referred to as T
_trans ) Is 120 ° C and Gd _0.30 (Fe _0.85 Co
_0.15 ) The recording / reproducing characteristics when _0.70 is used are shown. In the present embodiment, the result of investigating the recording / reproducing characteristics by changing the composition of the transfer layer 3 ″ will be described.

Table 21 shows that the transfer layer 3 ″ was formed of a 30 nm-thick G layer.
As _x (Fe _0.80 Co _0.20 ) _1-X , X (atom ratio)
By changing the value, the T _trans of the transfer layer 3 ", the wavelength 680n
5 shows the result of measurement of the CNR (signal-to-noise ratio) at 0.3 μm measured by an optical pickup using a m semiconductor laser.

[0290]

[Table 21]

In Table 21, the CNR (34.0 dB) obtained in Comparative Example 1 in which the transfer layer 3 ″ was not formed.
CNR higher than 0.22 ≦ X ≦ 0.2.
It can be seen that the range is 35. The reproducing layer 1 used in the present embodiment is the same as that of the fourth embodiment.
At the temperature of ° C., the state becomes perpendicular magnetization. That is, the transfer layer 3 ″
It suffices if the in-plane magnetization mask of the reproducing layer 1 can be emphasized at a temperature of 120 ° C. or lower. However, if T _trans is too low, the mask effect is weakened, so that X ≧ 0.22 is preferable. Further, if T _trans is too high, transfer to the reproducing layer 1 can be performed to some extent, but if T _trans is too high, recorded information cannot be sufficiently transferred to the reproducing layer 1. Therefore, when the transfer layer 3 ″ becomes perpendicularly magnetized at a temperature higher than the temperature at which the reproducing layer 1 becomes a perpendicular magnetization film, the mask state is maintained. Therefore, it is desirable that the transfer layer 3 ″ be perpendicularly magnetized at the reproducing temperature.

Further, in Embodiments 11 and 12,
As for the transfer layer 3 ″, it is sufficient that T _trans satisfies the above condition, but by setting the Curie temperature to be equal to or lower than the Curie temperature of the recording layer, magnetic influence is not exerted at the time of recording, so that stable recording can be performed. Embodiment 11
And 12 describe the results using GdFeCo, but it is sufficient that T _trans satisfies the above conditions, and in addition, GdNdFe, GdNdFeCo, GdTbFe,
GdTbFeCo, GdDyFeCo, GdDyFe,
It is possible to use a transfer layer 3 ″ made of GdFe or the like.

The thickness of the reproducing layer 1 and the transfer layer and the thickness of the non-magnetic intermediate layer 2 were similar to those of the eleventh embodiment.

(Embodiment 13) Embodiment 1 of the present invention
3 will be described below with reference to FIG. In the present embodiment, a case where a magneto-optical disk is applied as a magneto-optical recording medium will be described. However, the description of the same parts as those in Embodiments 11 to 13 will be omitted.

The magneto-optical disk according to the thirteenth embodiment has a substrate 6, a transparent dielectric layer 7, a reproducing layer 1, a non-magnetic intermediate layer 2, a reflective layer 10, a transfer layer 3 ″, as shown in FIG. The recording layer 4, the protective layer 8, and the overcoat layer 9 have a disk body laminated in this order.

In the eleventh embodiment, when the film thickness of the transfer layer 3 ″ is smaller than 10 nm, the light beam 5 transmitted through the reproducing layer 1 and the non-magnetic intermediate layer 2 is reflected by the recording layer 4 and reproduced. Since the information of the recording layer 4 is mixed with the signal, the effect of the mask due to the in-plane magnetization of the reproduction layer 1 and the transfer layer 3 ″ is reduced.

The magneto-optical disk of the thirteenth embodiment has the same structure as that of the magneto-optical disk of the eleventh embodiment except that the reflection layer 10 is formed between the nonmagnetic intermediate layer 3 and the transfer layer 3 ″. This makes it possible to prevent the light beam 5 transmitted through the reproduction layer 1 from being reflected by the reflection layer 10 and mixing information of the recording layer 4 into a reproduction signal.

Hereinafter, a specific example of the magneto-optical disk of the present embodiment will be described with respect to (1) the forming method and (2) the recording / reproducing characteristics.

(1) Forming Method The magneto-optical disk of the present embodiment is the same as the magneto-optical disk forming method of Embodiment 11, except that the reflection layer made of Al is provided between the nonmagnetic intermediate layer 2 and the transfer layer 3 ″. Layer 10, a substrate 6, a transparent dielectric layer 7, a reproducing layer 1, a non-magnetic intermediate layer 2, a transfer layer 3 ″, a recording layer 4, a protective layer 8, and an overcoat layer 9 were formed as in Example 4. Similarly, the thickness of the reproducing layer 1 is set to 2
The transfer layer 3 ″ was formed to have a thickness of 20 nm.

Here, after forming the nonmagnetic intermediate layer 2, the Al reflecting layer 10 was again exposed to 1 × 10 ⁻⁶ T in the sputtering apparatus.
after evacuating to orr and introducing argon gas, A
l Supply power to the target and set the gas pressure to 4 × 10 ^-3 To
rr, a reflective layer 10 made of Al was formed on the nonmagnetic intermediate layer 2 with a thickness of 2 to 80 nm.

(2) Recording / Reproducing Characteristics Table 22 shows the CNR (signal to noise) at 0.3 μm measured by an optical pickup using a semiconductor laser having a wavelength of 680 nm while changing the thickness of the reflective layer 10 in Example 3. ratio)
It shows.

[0302]

[Table 22]

In Table 22, the thickness of the reflective layer of 0 nm indicates the result of Comparative Example 4 in which the reflective layer 10 was not formed. Even when the thickness of the reflective layer 10 is extremely thin, such as 2 nm, the effect of blocking information reproduction from the recording layer 4 is observed, and the CNR increases by 1.0 dB. By increasing the thickness of the reflective layer 10, the CNR gradually increases, and the CNR becomes maximum at the thickness of 20 nm. This is because the effect of blocking information reproduction from the recording layer 4 becomes more remarkable as the thickness of the reflective layer increases. Although the CNR is reduced when the film thickness is 30 nm or more, the magnetostatic coupling force acting between the recording layer 4 and the reproducing layer 1 becomes weaker as the distance between the recording layer 4 and the reproducing layer 1 increases. From the above, in order to obtain a higher CNR than that of Comparative Example 4, the thickness of the reflective layer 10 is set to 2 to 5
It can be seen that it is necessary to set within the range of 0 nm.

(Embodiment 14) In Embodiment 13, the reproduction characteristics using Al as the reflection layer 10 are described. In this embodiment, however, the reflection characteristics are improved in order to improve the recording characteristics. The result of using an alloy of Al and a metal other than Al as the layer 10 will be described.

Table 23 shows that the reflective layer 10 was made of A having a thickness of 20 nm.
By changing the value of X (atom ratio) as l _1-x Fe _x , the CNR (signal-to-noise ratio) at 0.3 μm and the magnitude of the erasing magnetic field measured by an optical pickup using a semiconductor laser having a wavelength of 680 nm. Is shown.

[0306]

[Table 23]

From Table 23, it can be seen that as the Fe content increases, that is, as X becomes greater than 0.10, the CNR gradually decreases.
The NR is also larger than that of Comparative Example 4, and the effect of forming the reflective layer 10 can be seen. On the other hand, when looking at the erasing magnetic field, when the reflective layer 10 made of pure Al is used, a large erasing magnetic field of 50 kA / m is required, whereas X is set to 0.02 or more and 0.2 to 0.2.
By setting it to 50 or less, it was possible to reduce the erasing magnetic field.

Next, Table 24 shows that the reflective layer 10 was formed to a thickness of 20 n.
The CNR (signal-to-noise ratio) at 0.3 μm measured by an optical pickup using a semiconductor laser having a wavelength of 680 nm while changing the value of X (atom ratio) as Al _1-x Ni _x of m
And the magnitude of the erasing magnetic field.

[0309]

[Table 24]

[0310] From Table 24, it is possible to reduce the erasing magnetic field by setting X to be 0.02 or more and 0.50 or less, as in the case where Fe is contained.

In addition to Fe and Ni, Co, Gd, Tb, D
By similarly including magnetic metals such as y and Nd in Al, the erasing magnetic field can be reduced.

(Embodiment 15) In this embodiment, a case where a different material is used as the reflection layer 10 in the specific example of Embodiment 13 will be described.

[0313] In the fourteenth embodiment, the result in which a magnetic metal element is contained in Al as the reflection layer 10 is described. However, in the present embodiment, the case where a nonmagnetic metal element is contained in Al is described. This section describes the improvement of recording characteristics.

Table 25 shows that the reflective layer 10 was formed of a 20 nm thick A
By changing the value of X (atom ratio) as l _1-x Ti _X , the CNR (signal-to-noise ratio) at 0.3 μm and the magnitude of the erasing magnetic field were measured with an optical pickup using a semiconductor laser having a wavelength of 680 nm. Is shown.

[0315]

[Table 25]

As can be seen from Table 25, as the Ti content increases, that is, as X becomes larger than 0.10, the CNR gradually decreases.
The NR is larger than that of Comparative Example 4, and the effect of forming the reflective layer 10 can be seen. On the other hand, when looking at the erasing magnetic field, when the reflective layer 10 made of pure Al is used, a large erasing magnetic field of 50 kA / m is required, whereas X is set to 0.02 or more and 0.2 to 0.2.
By setting it to 98 or less, it was possible to reduce the erasing magnetic field.

Next, Table 26 shows that the reflective layer 10 is made of Ti
The non-magnetic elements other than are those showing the erasing magnetic field reduction effect when the content of the Al, a reflective layer 10 Al _0.5 Z
_{When 0.5 is used} as the Z value, the CNR (signal-to-noise ratio) at 0.3 μm and the magnitude of the erasing magnetic field measured by an optical pickup using a semiconductor laser having a wavelength of 680 nm when Z is a nonmagnetic metal other than Ti are shown. ing.

[0318]

[Table 26]

From Table 26, it is found that Z is a nonmagnetic metal T
In the case where a, Pt, Au, Cu, and Si were used, all of the CNRs were larger than Comparative Example 4, and the effect of forming the reflective layer 10 was observed. On the other hand, looking at the erasing magnetic field,
It was possible to reduce the erasing magnetic field in the same manner as in the case where Ti was contained in the steel.

In the thirteenth to fifteenth embodiments, the same results as in the eleventh and twelfth embodiments were obtained with respect to the thicknesses of the reproducing layer 1 and the transfer layer, and the thickness of the non-magnetic intermediate layer 2.

In the above embodiments 11 to 15, the reproducing layer 1
Although a magnetic layer that is in an in-plane magnetization state at room temperature and becomes a perpendicular magnetization state at a high temperature state is used, at least a signal reproduction region (a region heated to a predetermined temperature (reproduction temperature) or more during reproduction) has a perpendicular magnetization state. Can be used.

In Embodiments 11 to 15, the transfer layer 3 ″ is adjacent to the recording layer 4, but may be magnetostatically coupled to the recording layer 4 (see Embodiment 17). .
By providing a non-magnetic intermediate layer between the transfer layer 3 ″ and the recording layer 4, the mask effect can be enhanced.

In the first to fifteenth embodiments described above, a recording auxiliary layer may be provided between the recording layer 4 and the protective layer 5. For example, a material that exhibits perpendicular magnetization in the recording auxiliary layer, has a higher Curie temperature than the recording layer, and reverses magnetization at a lower magnetic field than the recording layer is used. In this case, the recording can be performed with a lower magnetic field by first reversing the magnetization of the recording auxiliary layer during recording and reversing the magnetization of the recording layer by the exchange coupling force.

In the first to fifteenth embodiments, a laminated film of Co and Pt may be used as the reproducing layer 1. For example, a layer in which a total of 30 layers of a 0.4 nm Co layer and a 0.9 nm Pt layer are alternately laminated can be used (total film thickness is 1 layer).
9.5 nm, Curie temperature 300 ° C). As described above, when the laminated film of Co and Pt is used, the Kerr rotation angle can be increased when short-wavelength light is used, and the reproduction signal quality can be further improved.

(Embodiment 16) An embodiment of the present invention is described below with reference to FIG.
In the present embodiment, a case where a magneto-optical disk is applied as a magneto-optical recording medium will be described.

As shown in FIG. 17, the substrate 6, the transparent dielectric layer 7, the reproducing layer 1, the first non-magnetic intermediate layer 20, the in-plane magnetic layer 3, the second non-magnetic intermediate layer 30, the recording layer 4, the protective layer The layer 7 and the overcoat layer 8 have a disk body laminated in this order. The basic characteristics of each layer other than the second nonmagnetic intermediate layer 30 are the same as those described in the first to sixth embodiments.

The second non-magnetic intermediate layer 30 is made of AlN,
It consists of one layer of a dielectric such as SiN, AlSiN, SiO ₂ , one layer of a non-magnetic metal alloy such as Al, Ti, Ta, or a combination of two or more layers of the above-mentioned dielectric and the above-mentioned metal. The layer 3 and the recording layer 4 are set to be magnetostatically coupled.

Hereinafter, specific examples of the magneto-optical disk having the above-described configuration will be described with respect to (1) a forming method and (2) recording / reproducing characteristics.

(1) Forming Method The forming method is substantially the same as the above-described forming method, and only different points will be described. The method of forming the transparent dielectric layer 7, the reproducing layer 1, the first non-magnetic intermediate layer 20, and the in-plane magnetic layer 3 is the same as in the previous embodiments. The method of forming the second non-magnetic intermediate layer 30 is as follows.

After the in-plane magnetization layer 3 was formed, the inside of the sputtering apparatus was again evacuated to 1 × 10 ^-6 Torr, a mixed gas of argon and nitrogen was introduced, power was supplied to the Al target, and the gas pressure was changed to 4 × 10 ⁻⁶ Torr. Under the condition of × 10 ^-3 Torr, the in-plane magnetization layer 3
A second non-magnetic intermediate layer 30 made of AlN was formed thereon.

Subsequently, the inside of the sputtering apparatus was again set to 1 × 10
After evacuating to ^-6 Torr, the recording layer 4 and the protective layer 7 made of AlN were formed on the second nonmagnetic intermediate layer 30 in the same manner as in the above-described embodiment.

Next, an ultraviolet curable resin was applied on the protective layer 7 by spin coating, and irradiated with ultraviolet rays to form an overcoat layer 8.

(2) Recording / reproducing characteristics The disk was measured with an optical pickup using a semiconductor laser having a wavelength of 680 nm. Table 27 shows the result of measuring the CNR at 0.3 μm by changing the thickness of the second nonmagnetic intermediate layer 30.

[0334]

[Table 27]

In Table 27, the thickness of the second non-magnetic intermediate layer 30 of 0 nm indicates the result when the second non-magnetic intermediate layer 20 was not formed. As you can see here, the second
By providing the nonmagnetic intermediate layer 20 up to a thickness of 80 nm, a high CNR is obtained.

This will be described below. When the second non-magnetic intermediate layer 30 is not provided, the magnetization of the in-plane magnetization layer 3 is in a state where the magnetization is easily oriented in the vertical direction due to the exchange coupling force from the recording layer 4. If the temperature rises during regeneration,
When the magnetization of the in-plane magnetic layer 3 decreases, the magnetization of the in-plane magnetic layer 3 is oriented in the perpendicular direction due to the exchange coupling force from the recording layer 4. Therefore, the magnetization from the recording layer 4 is leaked to the reproducing layer 1 even in a region which functions as a mask layer at a predetermined temperature or lower.

On the other hand, when the second non-magnetic intermediate layer 30 is provided, the in-plane magnetic layer 3 and the recording layer 4 do not undergo exchange coupling. Therefore, even if the temperature rises during reproduction, the magnetization of the in-plane magnetic layer 3 remains in the in-plane direction in a region below the predetermined temperature. For this reason, a mask effect can be further obtained in a region below a predetermined temperature.

However, if the thickness of the second non-magnetic intermediate layer 30 is too large, the magnetostatic coupling force with the reproducing layer 1 will be weak, and the information on the recording layer 4 will not be transferred to the reproducing layer 1. Therefore, the thickness of the second nonmagnetic intermediate layer 30 is
The thickness is preferably 2 nm or more and 80 nm or less.

As the second non-magnetic intermediate layer 30, any material may be used as long as it can block the exchange coupling force between the in-plane magnetic layer 3 and the recording layer 4, but the transparent dielectric layer 7 or the first non-magnetic intermediate layer can be used. If one or both of the layers 20 is the same (for example, if it is unified to AlN as in the present embodiment), the manufacturing process can be simplified.

(Embodiment 17) The embodiment of the present invention is described below with reference to FIG.
In the present embodiment, a case where a magneto-optical disk is applied as a magneto-optical recording medium will be described.

As shown in FIG. 17, the substrate 6, the transparent dielectric layer 7, the reproducing layer 1, the first non-magnetic intermediate layer 20, the transfer layer 3 ″,
The second non-magnetic intermediate layer 30, the recording layer 4, the protective layer 7, and the overcoat layer 8 have a disk body laminated in this order.

The basic characteristics of each layer other than the second nonmagnetic intermediate layer are the same as those described in the above-described embodiments 11 to 15.

The second non-magnetic intermediate layer 30 is made of AlN,
The transfer layer 3 is made of one layer of a dielectric such as SiN, AlSiN, SiO ₂ , one layer of a non-magnetic metal alloy such as Al, Ti, Ta, or a combination of two or more layers of the above dielectric and the above metal. And the recording layer 4 are set to be magnetostatically coupled.

Hereinafter, specific examples of the magneto-optical disk having the above configuration will be described with respect to (1) a forming method and (2) recording / reproducing characteristics.

(1) Forming method The forming method is substantially the same as the above-described forming method, and only different points will be described. The method of forming the transparent dielectric layer 7, the reproducing layer 1, the first non-magnetic intermediate layer 20, and the transfer layer 3 ″ is the same as that of the previous embodiment. The method of forming the second non-magnetic intermediate layer 30 is as follows. It is on the street.

After the transfer layer 3 ″ was formed, the inside of the sputtering apparatus was again evacuated to 1 × 10 ⁻⁶ Torr, a mixed gas of argon and nitrogen was introduced, and power was supplied to the Al target.
Under the condition of a gas pressure of 4 × 10 ⁻³ Torr, A
A second non-magnetic intermediate layer 30 of 1N was formed.

Subsequently, the inside of the sputtering apparatus was again set to 1 × 10
After evacuating to ^-6 Torr, the recording layer 4 and the protective layer 7 made of AlN were formed on the second nonmagnetic intermediate layer 30 in the same manner as in the above-described embodiment. Next, on the protective layer 7,
The overcoat layer 8 was formed by applying an ultraviolet curable resin by spin coating and irradiating ultraviolet rays.

(2) Recording / Reproducing Characteristics The disc was measured with an optical pickup using a semiconductor laser having a wavelength of 680 nm. Table 28 shows the result of measuring the CNR at 0.3 μm by changing the thickness of the second nonmagnetic intermediate layer 30.

[0349]

[Table 28]

In Table 28, the thickness of the second non-magnetic intermediate layer 30 of 0 nm shows the result when the second non-magnetic intermediate layer 30 was not formed. As can be seen from this table, a high CNR is obtained by providing the second non-magnetic intermediate layer 30 to a thickness of 80 nm.

This will be described below. When the second non-magnetic intermediate layer 30 is not provided, the magnetization of the transfer layer 3 ″ tends to be oriented in the vertical direction due to the exchange coupling force from the recording layer 4. When the magnetization of the transfer layer 3 ″ decreases, the magnetization of the transfer layer 3 ″ is oriented in the vertical direction due to the exchange coupling force from the recording layer 4. Is leaked to the reproducing layer 1.

On the other hand, when the second nonmagnetic intermediate layer 30 is provided, the transfer layer 3 "and the recording layer 4 are not exchange-coupled. Therefore, even if the temperature rises during reproduction, the transfer layer 3" The magnetization remains in the in-plane direction, and shifts to perpendicular magnetization at a predetermined temperature or higher. For this reason, a mask effect can be further obtained in a region below a predetermined temperature.

However, if the thickness of the second non-magnetic intermediate layer 30 is too large, the magnetostatic coupling force with the reproducing layer 1 will be weak, and the information on the recording layer 4 will not be transferred to the reproducing layer 1. Therefore, the thickness of the second nonmagnetic intermediate layer 30 is
The thickness is preferably 2 nm or more and 80 nm or less.

As the second non-magnetic intermediate layer 30, any material may be used as long as it can block the exchange coupling force between the transfer layer 3 ″ and the recording layer 4, but the transparent dielectric layer 7 or the first non-magnetic intermediate layer 30 can be used. If one or both of the layers 20 is the same (for example, if it is unified to AlN as in the present embodiment), the manufacturing process can be simplified.

[0355]

【The invention's effect】

(1) In the magneto-optical recording medium of the present invention, since the leakage magnetic flux from the recording layer can be suppressed from being transmitted to the reproducing layer at least at room temperature, the influence of the magnetization of the adjacent recording magnetic domain at the time of reproduction is eliminated, and the desired recording is performed. Only information from the magnetic domains can be extracted, and an increase in recording density can be realized. This enables recording and reproduction with a smaller bit diameter and a smaller recording bit interval.

(2) By forming a magnetic domain larger than the recording magnetic domain of the recording layer in the reproducing layer, in addition to the effect of (1), the reproduction signal amount can be increased and the signal quality can be improved.

(3) Further, when the in-plane magnetic layer is used as a magnetization mask, the in-plane magnetic layer can absorb the magnetic field generated from the recording layer at room temperature and cut off the magnetic field from the recording layer in the reproducing layer. On the other hand, when the laser beam for reproduction is heated by irradiation, the magnetization of the in-plane magnetic layer decreases, so that the above-mentioned magnetic field blocking effect is lost, and the magnetic flux from the recording layer leaks to the reproduction layer in the heated region. Thus, the reproducing layer can be made to have perpendicular magnetization according to the recorded information. here,
Since information only from the heated minute area is transmitted to the reproduction layer, a sufficient reproduction signal can be obtained even when recording and reproduction are performed with a small recording bit length and a small recording bit interval.

(4) If the magnetization of the in-plane magnetization layer at room temperature is made larger than the magnetization of the recording layer at room temperature, the above-mentioned magnetic field blocking effect can be ensured.

(5) Further, by heating during reproduction, the in-plane magnetic layer becomes higher than the Curie temperature and the magnetization disappears, and the recording layer is preferably kept at the Curie temperature or lower in order to retain information recorded at that time. That is, it is desirable to set the Curie temperature of the recording layer lower than the Curie temperature of the in-plane magnetic layer.

(6) Since the reproducing layer is required to have reproducing characteristics, it is advantageous that the Curie temperature is higher than that of the recording layer.

(7) A transparent dielectric layer, a reproducing layer,
If a non-magnetic intermediate layer, an in-plane magnetic layer, a recording layer, and a protective layer are sequentially formed, a part of the bit information recorded in the recording layer is selected by a magnetic mask using the in-plane magnetic layer, and the magnetic domain of the reproducing layer is selected. Can be reproduced in large scale, and even in high-density recording,
A sufficiently large signal strength can be obtained. Further, the exchange coupling between the reproducing layer and the in-plane magnetic layer is completely cut off by the non-magnetic intermediate layer,
Good magnetostatic coupling between the reproducing layer and the recording layer can be realized.

(8) If the thickness of the in-plane magnetic layer is set to 2 nm or more and 40 nm or less in (7), the mask effect of the recording layer by the in-plane magnetic layer is set to a favorable state. In addition, stable magnetic domain expansion reproduction can be performed.

(9) In the above (7) and (8), the magnetic mask layer is made of a GdFe alloy, a GdFeAl alloy, a GdFe alloy.
Ti alloy, GdFeTa alloy, GdFePt alloy, Gd
FeAu alloy, GdFeCu alloy, GdFeAlTi alloy, or GdFeAlTa alloy,
It is possible to stably form a magnetic domain in the reproducing layer, to correctly react to a magnetic field coming out of the recording layer, and to realize a good magnetic domain expansion reproduction.

(10) In (7) and (8) above,
(Gd_0.11Fe_0.89) _XAl_1-XAnd X
If the (atom ratio) is 0.30 or more and 1.00 or less, magnetic
That the magnetic properties of the magnetic mask layer (in-plane magnetic layer) are optimized.
Good exchange coupling between the recording layer and the in-plane magnetization layer
State can be realized, and good magnetic domain expansion reproduction can be realized.
it can.

(11) In the above (7) to (10),
If the Curie temperature of the magnetic mask layer is 60 ° C. or more and 220 ° C. or less, the Curie temperature of the magnetic mask layer is optimized. The magnetic layer is shielded from the reproducing layer by (magnetic mask), and at a temperature equal to or higher than the Curie temperature of the magnetic mask layer, the magnetostatic coupling between the recording layer and the reproducing layer is kept good, and stable magnetic domain expansion reproduction can be realized. It becomes possible.

(12) If a magnetic mask layer whose total magnetization is in the opposite direction to that of the recording layer is used, the magnetic field generated from the recording layer and affecting the reproducing layer can be reduced. The magnetization direction is determined by the influence of only the recording bits existing in the central portion of, and reproduction can be performed with a minute recording bit interval and a minute recording bit width.

(13) In the above (12), if the magnetic field generated from the recording layer in the low-temperature region at the time of information reproduction is reduced by the rare earth metal-rich magnetic mask layer adjacent to the transition metal-rich recording layer, the reproduction can be performed. The magnetization direction of the layer is determined only by the recording bit existing at the center of the light beam spot, and reproduction can be performed at a minute recording bit interval and a minute recording bit width.

(14) In the above (12) and (13), if the magnetic mask layer is one whose magnetization is reduced by heating at the time of reproducing information, magnetic flux leaks from the recording layer to the reproducing layer in a low temperature region. On the other hand, in the high temperature region, the magnetic flux from the recording layer can leak to the reproducing layer, and the magnetization direction of the reproducing layer can be reliably determined by information from a single recording bit in the recording layer. Thus, the quality of the reproduced signal can be improved.

(15) In the above (12) to (14), by making the magnetization of the magnetic mask layer at room temperature substantially the same as the magnetization of the recording layer at room temperature, a magnetic field from the recording layer in the low temperature region is applied to the reproducing layer. It can be made not to act, and the reproduction signal quality can be improved.

(16) In the above (12) to (15), if the Curie temperature of the magnetic mask layer is lower than the Curie temperature of the recording layer, the magnetic mask layer is heated to near the Curie temperature during reproduction to reduce its magnetization. The recording layer can hold the information recorded at that time.

(17) In the above (12) to (16), if the compensation temperature of the magnetic mask layer is lower than the Curie temperature of the recording layer, the interruption layer is heated to near the compensation temperature during reproduction to reduce its magnetization. The recording layer can hold the information recorded at that time.

(18) In the above items (12) to (17), a transparent dielectric layer, a reproducing layer,
By adopting a structure in which a non-magnetic intermediate layer, a magnetic mask layer, a recording layer, and a protective layer are sequentially formed, only a part of the bit information recorded in the recording layer in a small size is selected with a magnetization mask by a blocking layer, and the reproducing layer is A stable reproducing operation can be performed by forming a large enlarged magnetic domain. Further, the non-magnetic intermediate layer completely shuts off exchange coupling between the reproducing layer, the magnetic mask layer, and the recording layer, and realizes good magnetostatic coupling between the reproducing layer, the magnetic mask layer, and the recording layer. It becomes possible.

(19) In the above (18), by setting the thickness of the magnetic mask layer to 10 nm or more and 60 nm or less, it is possible to emphasize the effect of the shielding layer on the magnetic field from the recording layer in the reproducing layer. In addition, by optimizing the thickness of the reproducing layer, it becomes possible to obtain a good reproducing signal.

(20) In the above (12) to (17), a transparent dielectric layer, a reproducing layer, a non-magnetic intermediate layer,
With the configuration in which the recording layer, the blocking layer, and the protective layer are sequentially formed, only a part of the bit information recorded small in the recording layer is selected with the magnetic mask by the magnetic mask layer, and the enlarged magnetic domain is formed in the reproducing layer. Thus, a stable reproducing operation can be performed. Further, the non-magnetic intermediate layer completely shuts off exchange coupling between the reproducing layer, the magnetic mask layer, and the recording layer, and realizes good magnetostatic coupling between the reproducing layer, the magnetic mask layer, and the recording layer. It becomes possible. Further, the magnetic domain transfer from the recording layer to the reproducing layer in the signal reproducing region is easily caused, and the selection range of the thickness of the blocking layer can be widened.

(21) In the above (20), by setting the thickness of the magnetic mask layer to 10 nm or more and 80 nm or less, it is possible to emphasize the effect of the magnetic mask layer on the magnetic field from the recording layer in the reproducing layer. Yes, a good reproduced signal can be obtained.

(22) In the above (18) to (21), the magnetic mask layer is made of a GdDyFe alloy, a TbFe alloy,
DyFe alloy, GdFe alloy, GdTbFe alloy, Dy
With a configuration made of an alloy containing either the FeCo alloy or the TbFeCo alloy, the magnetic mask layer can enhance the effect of masking the magnetic field from the recording layer in the reproduction layer, and a good reproduction signal can be obtained. .

(23) The Curie temperature of the magnetic mask layer is set to 8
When the temperature is set to 0 ° C. to 220 ° C., it is possible to enhance the mask effect of the magnetic field from the recording layer in the reproducing layer by the blocking layer in a low temperature region, and to apply the magnetic field from the recording layer to the reproducing layer in a high temperature (near the reproducing temperature). Leakage can be obtained, and a good reproduced signal can be obtained.

(24) In the above (18) to (23), if the compensation temperature of the magnetic mask layer is set to 80 ° C. to 220 ° C., the effect of the magnetic mask layer to mask the magnetic field from the recording layer in the reproducing layer in the low temperature region. Can be emphasized, and at a high temperature (near the reproduction temperature), the magnetic field from the recording layer can be leaked to the reproduction layer, and a good reproduction signal can be obtained.

(25) Since a magnetic layer that exhibits in-plane magnetization at room temperature and exhibits perpendicular magnetization at a predetermined temperature or higher at room temperature is used as the magnetic mask layer, the magnetic mask layer causes a magnetic field generated from the recording layer at room temperature. To absorb the magnetic field from the recording layer in the reproducing layer. In addition, since the portion heated by the laser beam irradiation for reproduction becomes near the compensation composition and exhibits perpendicular magnetization, the magnetic field blocking effect is lost, and the magnetic flux from the recording layer leaks to the reproduction layer in the heated region,
The reproduction layer can be made to have perpendicular magnetization according to the recorded information. Here, since information only from the heated minute area is transmitted to the reproduction layer, a sufficient reproduction signal can be obtained even when recording and reproduction are performed with a small recording bit length and a small recording bit interval. .

(26) In the above (25), by setting the Curie temperature of the magnetic mask layer to be equal to or lower than the Curie temperature of the recording layer, the magnetic mask layer does not affect the recording layer at the time of recording information, so that it is ensured. Can record.

(27) In the above (25) and (26), since the reproducing layer is required to have reproducing characteristics, it is advantageous that the Curie temperature is higher than that of the recording layer.

(28) In the above (25) to (27), a transparent dielectric layer, a reproducing layer, a non-magnetic intermediate layer,
If a magnetic mask layer, a recording layer, and a protective layer are sequentially formed, a portion of bit information recorded in a small size on the recording layer can be selected by using a magnetic mask formed by the magnetic mask layer, and can be greatly enlarged and reproduced by the magnetic domain of the reproducing layer. Even in high-density recording, a sufficiently large signal intensity can be obtained. Further, the exchange coupling between the reproducing layer and the magnetic mask layer is completely cut off by the non-magnetic intermediate layer, and good magnetostatic coupling between the reproducing layer and the magnetic mask layer and the recording layer can be realized.

(29) In the above (28), when the thickness of the magnetic mask layer is 2 nm or more and 40 nm or less, the effect of masking the recording layer by the in-plane magnetic layer is set to a favorable state. In addition, stable magnetic domain expansion reproduction can be performed.

(30) In the above (28) and (29), the magnetic mask layer is made of GdFeCo, GdNdFe, Gd
NdFeCo, GdTbFe, GdTbFeCo, Gd
If any alloy of DyFeCo, GdDyFe, and GdFe is used, stable magnetic domains of the reproducing layer can be achieved, and the magnetic layer coming out of the recording layer can correctly react to the magnetic field, and excellent magnetic domain expansion reproduction can be realized. Becomes possible.

(31) In the above (28) and (29), if the magnetic mask layer is Gd _x (Fe _0.80 Co _0.20 ) _1-X and X (atom ratio) is 0.10 or more and 0.35 or less, By optimizing the magnetic characteristics of the magnetic mask layer, a good exchange coupling state between the recording layer and the magnetic mask layer can be realized, and good magnetic domain expansion reproduction can be realized.

(32) The above (7), (18), (2)
In (0) and (28), when the thickness of the reproducing layer is 10 nm or more and 80 nm or less, it is possible to stabilize the magnetic domain in the reproducing layer, and to obtain a good reproducing signal by increasing the light interference effect. Becomes possible.

(33) The thickness of the non-magnetic intermediate layer is 1 nm
When the thickness is 80 nm or less, a favorable magnetostatic coupling state is realized by optimizing the thickness of the non-magnetic intermediate layer, magnetic super-resolution reproduction can be realized, and the optical interference effect also increases. .

(34) The above (7), (18), (2)
In (0) and (28), if a reflection layer is formed adjacent to the nonmagnetic intermediate layer on the recording layer side, the thickness of the reproduction layer becomes thin, and the light beam for reproduction transmitted through the reproduction layer is reflected. Information reproduction from the recording layer, which is reflected by the layer and is unnecessary for signal reproduction, can be optically completely blocked, and the signal reproduction characteristics are improved.

(35) In the above (34), if the reflection layer is made of Al and the film thickness is set to 2 nm or more and 40 nm or less, the thickness of the reflection layer made of Al is optimized, so that the light beam for reproduction is Is reflected by the reflection layer, the magnetic super-resolution reproduction signal reproduction characteristics are improved, and the magnetostatic coupling force acting between the reproduction layer and the recording layer can be maintained in a good state.

(36) In the above (34), if the reflection layer is made of an alloy of Al and a magnetic metal, the reflection layer alloy is made of Al
Because the thermal conductivity is lower than that of the recording layer, the temperature distribution of the medium during heating by the laser beam becomes sharper, which makes it possible to realize good magnetic amplification and reproduction, and the magnetic properties of the recording layer formed on the reflective layer. Characteristics can be improved, and a magneto-optical recording medium that can be erased with a smaller erasing magnetic field can be provided.

(37) In the above (36), if the reflection layer is made of Al _1-x Fe _x and X (atom ratio) is set to 0.02 or more and 0.50 or less, excellent magnetic amplification reproduction can be realized. And the magnetic characteristics of the recording layer formed on the reflective layer are optimized, so that a magneto-optical disk erasable with a smaller erasing magnetic field can be provided.

(38) In the above (36), if the reflection layer is made of Al _1-x Ni _x and X (atom ratio) is set to 0.02 or more and 0.50 or less, excellent magnetic amplification reproduction can be realized. And the magnetic characteristics of the recording layer formed on the reflective layer are optimized, and a magneto-optical recording medium erasable with a smaller erasing magnetic field can be provided.

(39) In the above (34), if the reflective layer is made of an alloy of Al and a non-magnetic metal, good magnetic amplification reproduction can be realized, and the recording layer formed on the reflective layer can be realized. Has improved magnetic characteristics, and it is possible to provide a magneto-optical disk erasable with a smaller erasing magnetic field.

(40) In the above (39), if the non-magnetic metal is any one of Ti, Ta, Pt, Au, Cu, and Si, excellent magnetic amplification reproduction can be realized. In addition, the magnetic characteristics of the recording layer formed on the reflective layer are improved, and a magneto-optical disk erasable with a smaller erasing magnetic field can be provided.

(41) In the above (39), when the nonmagnetic metal is Al _1-x Ti _x , X (atom ratio) is 0.02.
When the ratio is not less than 0.98, good magnetic amplification and reproduction can be realized, and the magnetic characteristics of the recording layer formed on the reflective layer are optimized. It is possible to provide a magnetic disk.

(42) The above (7), (18), (2)
In (0) and (28), if a heat radiation layer is formed on the opposite side of the substrate with respect to the protective layer, the temperature distribution in the light beam irradiated on the magneto-optical recording medium becomes steeper, and the magnetic mask The effect of masking the magnetic field from the recording layer in the reproducing layer can be enhanced, and the reproducing characteristics are further improved.

(43) In the above (1) to (42),
If the reproducing layer is in the in-plane magnetization state at room temperature, it is advantageous that unnecessary signals need not be reproduced. Everything outside the magnetic domain generated in the reproducing layer may be a noise component,
By using the reproducing layer exhibiting the in-plane magnetization at room temperature, only the magnetic domains transferred from the recording layer become perpendicular magnetization, and the signal can be reproduced only in the vertical region.

(44) The above (1), (2), (3),
In (12) and (25), if the reproducing layer is a multilayer film of Co and Pt, a good C / N ratio can be obtained even when a short wavelength laser is used.

(45) When information is reproduced from the magneto-optical recording medium of the above (1) to (44), erasing the magnetic domains formed in the reproducing layer once leads to a smooth reproducing operation. When the laser beam for pulse emission is used, the magnetic domains are extinguished while the laser is extinguished, and the medium temperature is increased while the laser is emitting to transfer the recording magnetic domains of the recording layer to the reproducing layer. Signal reproduction, and the reproduction signal quality can be made higher.

(46) When reproducing information from the magneto-optical recording medium of the above (3) or (14), if the magnetic mask layer is heated above the Curie temperature, the magnetization of the magnetic mask layer can be eliminated. It is possible to smoothly transfer the magnetization from the recording layer to the reproduction layer during reproduction.

(47) When reproducing information from the magneto-optical recording medium of the above (25), if the magnetic mask layer is heated to a temperature higher than the temperature at which the magnetic mask layer becomes perpendicularly magnetized, the magnetization from the recording layer to the reproducing layer during reproduction is increased. Transfer can be performed smoothly.

(48) In the above (1) to (7), if the magnetic mask layer is to be magnetostatically coupled to the recording layer, the exchange coupling between the magnetic mask layer and the recording layer can be cut off. The effect can be obtained, and further excellent signal strength can be obtained.

(49) In the above (25) to (28), if the magnetic mask layer is magnetostatically coupled to the recording layer, the exchange coupling between the magnetic mask layer and the recording layer can be cut off, so that a higher mask The effect can be obtained, and further excellent signal strength can be obtained.

(50) In the above (48) to (49), the film thickness between the magnetic mask layer and the recording layer is 2 to 80 nm.
If the non-magnetic intermediate layer is disposed, the effects (48) and (49) can be obtained appropriately.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the principle of reproducing a magneto-optical disk according to Embodiments 1 to 6 of the present invention.

FIG. 2 is a diagram illustrating a conventional magneto-optical disk.

FIG. 3 is a diagram showing a film configuration of the magneto-optical disk according to the first embodiment of the present invention.

FIG. 4 is a diagram showing recording / reproducing characteristics of the magneto-optical disk according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a film configuration of a magneto-optical disk according to a fourth embodiment of the present invention.

FIG. 6 is a diagram for explaining a principle of reproducing a magneto-optical disk according to the seventh to tenth embodiments of the present invention.

FIG. 7 is a diagram showing a film configuration of a magneto-optical disk according to a seventh embodiment of the present invention.

FIG. 8 is a diagram showing recording / reproducing characteristics of a magneto-optical disk according to a seventh embodiment of the present invention.

FIG. 9 is a diagram showing a film configuration of a magneto-optical disk according to an eighth embodiment of the present invention.

FIG. 10 is a diagram showing a film configuration of a magneto-optical disk according to a ninth embodiment of the present invention.

FIG. 11 is a diagram showing a film configuration of a magneto-optical disk according to a tenth embodiment of the present invention.

FIG. 12 is a diagram illustrating a principle of reproducing a magneto-optical disk according to Embodiments 11 to 15 of the present invention.

FIG. 13 is a diagram showing a film configuration of a magneto-optical disk according to Embodiment 11 of the present invention.

FIG. 14 is a diagram showing recording / reproducing characteristics of a magneto-optical disk according to Embodiment 11 of the present invention.

FIG. 15 is a diagram showing a film configuration of a magneto-optical disk according to Embodiment 13 of the present invention.

FIG. 16 is a diagram illustrating the principle of reproduction of a conventional super-resolution recording medium.

FIG. 17 is a diagram showing a film configuration of a magneto-optical disk according to Embodiments 16 and 17 of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 reproducing layer 2 non-magnetic intermediate layer 3 in-plane magnetic layer 3 ′ shielding layer 3 ″ transfer layer 4 recording layer 5 light beam 6 substrate 7 transparent dielectric layer 8 protective layer 9 overcoat layer 10 reflective layer 20 first non-magnetic intermediate Layer 30 Second non-magnetic intermediate layer 110 Heat dissipation layer

 ──────────────────────────────────────────────────続 き Continuation of the front page (31) Priority claim number Japanese Patent Application No. 9-232227 (32) Priority date Hei 9 (1997) August 28 (33) Priority claim country Japan (JP) (72) Inventor Go Mori, 22-22 Nagaikecho, Abeno-ku, Osaka, Osaka, Japan (72) Inventor Junsaku Nakajima 22-22 Nagaikecho, Abeno-ku, Osaka, Osaka, Japan Sharp Corporation (72) Inventor, Yoshiteru Murakami (22) Inventor Junji Hirokane 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Japan

Claims (50)

[Claims] 1. A magneto-optical recording medium having at least a reproducing layer in which a signal reproducing region is in a perpendicular magnetization state and a recording layer made of a perpendicular magnetic film magnetically coupled to the reproducing layer. And a magnetic mask layer for suppressing magnetic coupling between the recording layer and the reproducing layer at least at room temperature. 2. A recording medium comprising: a reproducing layer in which at least a signal reproducing region is in a perpendicular magnetization state; and a recording layer made of a perpendicular magnetization film magnetically coupled to the reproducing layer. A magneto-optical recording medium in which a magnetic domain larger than a magnetic domain is formed in the reproducing layer, further comprising a magnetic mask layer disposed apart from the reproducing layer and suppressing magnetic coupling between the recording layer and the reproducing layer at least at room temperature. A magneto-optical recording medium, comprising: 3. The magneto-optical recording medium according to claim 1, wherein the magnetic mask layer comprises an in-plane magnetic layer whose magnetization decreases at a high temperature. 4. The magneto-optical recording medium according to claim 3, wherein at room temperature, the magnetization of the magnetic mask layer is larger than the magnetization of the recording layer. 5. The magneto-optical recording medium according to claim 3, wherein the Curie temperature of the magnetic mask layer is lower than the Curie temperature of the recording layer. 6. The magneto-optical recording medium according to claim 3, wherein a Curie temperature of the recording layer is lower than a Curie temperature of the reproducing layer. 7. The magneto-optical recording medium according to claim 3, wherein a transparent dielectric layer, said reproducing layer, a non-magnetic intermediate layer,
A magneto-optical recording medium, wherein the magnetic mask layer, the recording layer, and the protective layer are sequentially formed. 8. The magneto-optical recording medium according to claim 7, wherein the thickness of the magnetic mask layer is 2 nm or more and 40 nm or less. 9. The magneto-optical recording medium according to claim 7, wherein the magnetic mask layer is made of a GdFe alloy, a GdFeAl alloy,
GdFeTi alloy, GdFeTa alloy, GdFePt alloy, GdFeAu alloy, GdFeCu alloy, GdFeA
A magneto-optical recording medium comprising one of an alloy of 1Ti and a alloy of GdFeAlTa. 10. The magneto-optical recording medium according to claim 7, wherein the magnetic mask layer is represented by a composition formula of (Gd _0.11 Fe _0.89 ) _X Al _{1 -X} , and X ( atom ratio) is 0.30 or more and 1.
A magneto-optical recording medium having a diameter of 00 or less. 11. The magneto-optical recording medium according to claim 7, wherein the Curie temperature of the magnetic mask layer is 60 ° C. or more and 220 ° C.
A magneto-optical recording medium characterized by the following. 12. The magneto-optical recording medium according to claim 1, wherein the magnetic mask layer is formed of a magnetic layer whose total magnetization direction is opposite to that of the recording layer at least at room temperature. Characteristic magneto-optical recording medium. 13. The magneto-optical recording medium according to claim 12, wherein the recording layer is made of a transition metal-rich rare earth transition metal alloy film from room temperature to the Curie temperature, and the magnetic mask layer is made of a rare earth metal at least at room temperature. The magnetic mask layer is a perpendicular magnetization film made of a rare earth transition metal alloy formed such that the direction of the transition metal sublattice magnetization of the magnetic mask layer follows the direction of the transition metal sublattice magnetization of the recording layer. Magneto-optical recording medium. 14. The magneto-optical recording medium according to claim 12, wherein the magnetic mask layer is made of a magnetic film whose magnetization decreases at a high temperature. 15. The magneto-optical recording medium according to claim 12, wherein a total magnetization of the magnetic mask layer at room temperature is substantially the same as a total magnetization of the recording layer at room temperature. Characteristic magneto-optical recording medium. 16. The magneto-optical recording medium according to claim 12, wherein the Curie temperature of the magnetic mask layer is lower than the Curie temperature of the recording layer. . 17. The magneto-optical recording medium according to claim 12, wherein a compensation temperature of the magnetic mask layer is lower than a Curie temperature of the recording layer. Medium. 18. The magneto-optical recording medium according to claim 12, wherein a transparent dielectric layer, said reproducing layer, a non-magnetic intermediate layer,
A magneto-optical recording medium, wherein the magnetic mask layer, the recording layer, and the protective layer are sequentially formed. 19. The magneto-optical recording medium according to claim 18, wherein the thickness of the magnetic mask layer is 10 nm or more and 60 nm or less. 20. The magneto-optical recording medium according to claim 12, wherein a transparent dielectric layer, said reproducing layer, a non-magnetic intermediate layer,
A magneto-optical recording medium, comprising: the recording layer, the magnetic mask layer, and the protective layer sequentially formed. 21. The magneto-optical recording medium according to claim 20, wherein the thickness of the magnetic mask layer is 10 nm or more and 80 nm or less. 22. The magneto-optical recording medium according to claim 18, wherein the magnetic mask layer comprises a GdDyFe alloy, a TbFe alloy, a DyFe alloy, a GdFe alloy, a GdTbFe alloy,
A magneto-optical recording medium comprising an alloy containing either a DyFeCo alloy or a TbFeCo alloy. 23. The magneto-optical recording medium according to claim 18, wherein the Curie temperature of the magnetic mask layer is 80 ° C. or higher and 220 ° C. or higher.
A magneto-optical recording medium having a temperature of at most ℃. 24. The magneto-optical recording medium according to claim 18, wherein the compensation temperature of the magnetic mask layer is 80 ° C. or more and 220 ° C. or less. . 25. The magneto-optical recording medium according to claim 1, wherein the magnetic mask layer is a magnetic film having an in-plane magnetization state at room temperature and a perpendicular magnetization state at a predetermined temperature or higher. Characteristic magneto-optical recording medium. 26. The magneto-optical recording medium according to claim 25, wherein the Curie temperature of the magnetic mask layer is lower than the Curie temperature of the recording layer. 27. The magneto-optical recording medium according to claim 25, wherein the Curie temperature of the recording layer is lower than the Curie temperature of the reproducing layer. 28. The magneto-optical recording medium according to claim 25, wherein a transparent dielectric layer, the reproducing layer, a non-magnetic intermediate layer,
A magneto-optical recording medium, wherein the magnetic mask layer, the recording layer, and the protective layer are sequentially formed. 29. The magneto-optical recording medium according to claim 28, wherein the thickness of the magnetic mask layer is 2 nm or more and 40 nm or less. 30. The magneto-optical recording medium according to claim 28, wherein the magnetic mask layer is made of GdFeCo, GdNdFe, G
dNdFeCo, GdTbFe, GdTbFeCo, G
A magneto-optical recording medium comprising an alloy of dDyFeCo, GdDyFe, and GdFe. 31. The magneto-optical recording medium according to claim 28, wherein the magnetic mask layer is represented by a composition formula of Gd _x (Fe _0.80 Co _0.20 ) _1-X , wherein X ( atom ratio) is 0.10 or more and 0.1.
A magneto-optical recording medium having a diameter of 35 or less. 32. The magneto-optical recording medium according to claim 7, wherein the thickness of the reproduction layer is 10 nm or more and 80 nm or less. recoding media. 33. The magneto-optical recording medium according to claim 7, wherein the non-magnetic intermediate layer has a thickness of 1 nm or more and 80 nm or less. Magneto-optical recording medium. 34. The magneto-optical recording medium according to claim 7, 18 or 20, wherein a reflective layer is provided on the non-magnetic intermediate layer on the recording layer side of the non-magnetic intermediate layer. A magneto-optical recording medium formed adjacently. 35. The magneto-optical recording medium according to claim 34, wherein the reflection layer is made of Al and has a thickness of 2 nm or more and 40 nm or more.
nm or less. 36. The magneto-optical recording medium according to claim 34, wherein the reflection layer is made of an alloy of Al and a magnetic metal. 37. The magneto-optical recording medium according to claim 36, wherein the reflective layer is represented by a composition formula of Al _1-x Fe _x ,
A magneto-optical recording medium having an (atom ratio) of 0.02 or more and 0.50 or less. 38. The magneto-optical recording medium according to claim 36, wherein the reflective layer is represented by a composition formula of Al _{1 -X} Ni _X ,
A magneto-optical recording medium having an (atom ratio) of 0.02 or more and 0.50 or less. 39. The magneto-optical recording medium according to claim 34, wherein the reflection layer is made of an alloy of Al and a non-magnetic metal. 40. The magneto-optical recording medium according to claim 39, wherein the non-magnetic metal is Ti, Ta, Pt, Au, Cu, Si.
A magneto-optical recording medium, characterized by being any one of the above elements. 41. The magneto-optical recording medium according to claim 39, wherein the non-magnetic metal is represented by a composition formula of Al _{1 -X} Ti _X ,
A magneto-optical recording medium having an (atom ratio) of 0.02 or more and 0.98 or less. 42. The magneto-optical recording medium according to claim 7, 18 or 20, wherein a heat radiation layer is formed on a side opposite to the substrate with respect to the protective layer. A magneto-optical recording medium characterized by the following. 43. The magneto-optical recording medium according to claim 1, wherein the reproducing layer has an in-plane magnetization state at room temperature and a perpendicular magnetization state at high temperature. Magneto-optical recording medium. 44. The magneto-optical recording medium according to claim 1, wherein the reproducing layer comprises a multilayer film in which Co and Pt are alternately laminated. A magneto-optical recording medium characterized by the above-mentioned. 45. A reproducing method for reproducing information from a magneto-optical recording medium according to claim 1, wherein a light beam is radiated to the magneto-optical recording medium in a pulsed manner during signal reproduction. A method for reproducing a magneto-optical recording medium. 46. A reproducing method for reproducing information from a magneto-optical recording medium according to claim 3 or 14, wherein the reproducing method comprises irradiating the magneto-optical recording medium with a light beam at the time of reproducing, thereby reproducing the magnetic mask layer. A method for reproducing a magneto-optical recording medium, comprising heating the medium to a temperature near the Curie temperature or higher. 47. A reproducing method for reproducing information from a magneto-optical recording medium according to claim 25, wherein the reproducing is performed by irradiating the magneto-optical recording medium with a light beam so that the magnetic mask layer is at or above the predetermined temperature. A method for reproducing a magneto-optical recording medium, comprising: 48. The magneto-optical recording medium according to claim 1, wherein the magnetic mask layer is magnetostatically coupled to the recording layer. 49. The magneto-optical recording medium according to claim 25, wherein the magnetic mask layer is magnetostatically coupled to the recording layer. 50. The magneto-optical recording medium according to claim 48, wherein a non-magnetic intermediate layer is formed between the magnetic mask layer and the recording layer, and the film thickness of the non-magnetic intermediate layer Is 2 nm or more and 80 nm or less.