JP2001209984A - Magneto-optical recording medium, and magneto-optical disk device or method for reproducing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magneto-optical recording which increases the power margin of laser light suitable for reproducing and to provide a magnet-optical disk device and a method of reproducing signals from that magneto-optical recording medium. SOLUTION: The magneto-optical recording medium 10 has a reproducing layer 3, nonmagnetic layer 4, recording layer 5 and auxiliary magnetic layer 6. As for the auxiliary magnetic layer 6, a magnetic material showing the maximum saturation magnetization at 150 deg.C is used. As for the recording layer 5, a magnetic material showing the maximum saturation magnetization at 180 deg.C is used. The magneto-optical recording medium 10 is irradiated through the reproducing layer 3 side with laser light having the power to raise the temperature of the magneto-optical recording medium to the range from 150 deg.C to 180 deg.C so as to reproduce the signals recorded in the recording layer 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical recording medium for recording a signal by forming a magnetic domain, and a magneto-optical disk apparatus or a reproducing method for reproducing a signal from the magneto-optical recording medium.

[0002]

2. Description of the Related Art Magneto-optical recording media have attracted attention as rewritable, large-capacity, and highly reliable recording media, and have begun to be put to practical use as computer memories and the like. Recently, the recording capacity is 6.0 Gby.
tes's magneto-optical recording medium is AS-MO (Advanced)
d Storage Magneto Optica
l disk) standard and is about to be put to practical use.

[0003] Further, a 14 Gbyte by magnetic domain expansion reproduction method for reproducing signals by enlarging and transferring magnetic domains of a recording layer to a reproduction layer.
A magneto-optical recording medium having a recording capacity of es has also been proposed. The magneto-optical recording medium according to the AS-MO standard and the magneto-optical recording medium according to the magnetic domain expansion reproducing method have a recording layer and a reproducing layer, and when reproducing a signal, the magnetic domain of the recording layer is interposed via a nonmagnetic layer. It is transferred to the reproducing layer by magnetostatic coupling and detected by laser light. The power margin of the laser beam applied to the magneto-optical recording medium at the time of signal reproduction is determined by the balance between the coercive force of the reproducing layer and the magnitude of the leakage magnetic field from the recording layer. That is, when the magnitude of the leakage magnetic field from the recording layer is larger than the coercive force of the reproducing layer, the magnetic domain of the recording layer is transferred to the reproducing layer by magnetostatic coupling, and the magnitude of the leakage magnetic field from the recording layer is determined by the temperature of the recording layer. In order to accurately transfer the magnetic domains of the recording layer to the reproducing layer by magnetostatic coupling, the magnitude of the leakage magnetic field from the recording layer is larger than the coercive force of the reproducing layer, and It is necessary to control the power so that the magnitude of the leakage magnetic field from the recording layer is maximized and irradiate the magneto-optical recording medium with laser light.

In a conventional magneto-optical recording medium,
No attempt is made to control the magnitude of the leakage magnetic field from the recording layer.

[0005]

Therefore, in order to accurately transfer the magnetic domains of the recording layer to the reproducing layer by magnetostatic coupling in the conventional magneto-optical recording medium, the magnitude of the leakage magnetic field from the recording layer must be maximized. As a result, the power of the laser beam must be accurately controlled to irradiate the magneto-optical recording medium with the laser beam, which causes a problem that the power margin of the laser beam suitable for reproduction is reduced.

Accordingly, the present invention solves such a problem and provides a magneto-optical recording medium having a large power margin of laser light suitable for reproduction, and a magneto-optical disk apparatus or a reproducing method for reproducing signals from the magneto-optical recording medium. The purpose is to provide.

[0007]

According to the first aspect of the present invention, there is provided a magneto-optical recording medium in which magnetic domains are transferred from a recording layer to a reproducing layer by magnetostatic coupling, the reproduction of the magnetic domains formed in the recording layer. A recording layer having a first temperature at which the saturation magnetization is maximum, and an auxiliary magnetic layer having a second temperature at which the saturation magnetization is maximum. A magneto-optical recording medium having a first temperature and a second temperature different from each other.

In the magneto-optical recording medium according to the present invention, when the temperature of the magneto-optical recording medium rises between the first temperature and the second temperature by irradiating a laser beam, the recording layer changes from the recording layer to the reproducing layer. The magnitude of the leakage magnetic field is substantially constant between the first temperature and the second temperature. As a result, transfer from the recording layer to the reproduction layer by magnetostatic coupling is most likely to occur between the first temperature and the second temperature.

Therefore, according to the first aspect of the present invention, a signal is emitted by irradiating a laser beam having an intensity that raises the temperature of the magneto-optical recording medium between the first temperature and the second temperature. Can be reproduced reliably. As a result, the margin of the intensity of the laser beam required for reproducing the signal can be increased. According to a second aspect of the present invention, in the magneto-optical recording medium according to the first aspect, the reproducing layer has a first magnetic layer having a first transition temperature that changes from an in-plane magnetization film to a perpendicular magnetization film; A second magnetic layer having a second transition temperature that changes from an in-plane magnetic film to a perpendicular magnetic film. The first magnetic layer is formed on the recording layer side, and the second magnetic layer is formed on the side opposite to the recording layer. The magneto-optical recording medium is formed in contact with the first magnetic layer and has a second transition temperature lower than the first transition temperature.

[0010] In the magneto-optical recording medium according to the second aspect, the transfer of magnetic domains by the magnetostatic coupling from the recording layer to the reproducing layer is most likely to occur between the first temperature and the second temperature. The magnetic domain transferred from the recording layer to the first magnetic layer of the reproducing layer by magnetostatic coupling is transferred to the second magnetic layer of the reproducing layer by exchange coupling. The area of the recording layer where the magnetic domains are transferred is wider in the second magnetic layer than in the first magnetic layer.

Therefore, according to the second aspect of the present invention, it is possible to irradiate only a laser beam having an intensity that raises the temperature of the magneto-optical recording medium between the first temperature and the second temperature. The signal can be reproduced by magnetic domain expansion without applying an external magnetic field. According to a third aspect of the invention, in the magneto-optical recording medium according to the first or second aspect, the recording layer has a compensation temperature in a range of -30 ° C to 60 ° C.
The auxiliary magnetic layer has a compensation temperature of −30 ° C. to 6 ° C.
This is a magneto-optical recording medium made of GdFeCo or GdFe in a temperature range of 0 ° C.

In the magneto-optical recording medium according to the third aspect, the first temperature and the second temperature are set to 120 to 210.
It can be set to ° C. Therefore, according to the third aspect of the present invention, the first temperature and the second temperature are made different in the above-mentioned temperature range, and the temperature of the magneto-optical recording medium is set between the first temperature and the second temperature. It is easy to raise the temperature in between. As a result, a signal can be reproduced using a laser beam having a power in a relatively wide range of 1.0 to 2.0 mW.

According to a fourth aspect of the present invention, there is provided a magneto-optical disk drive for reproducing a signal from the magneto-optical recording medium according to the first aspect, wherein the magnetic head applies an alternating magnetic field to the magneto-optical recording medium; An optical head for irradiating the magneto-optical recording medium with laser light having an intensity at which the temperature of the magneto-optical recording medium is between the first temperature and the second temperature, and detecting the reflected light; It is.

According to a fourth aspect of the present invention, the temperature of the magneto-optical recording medium is raised between the first temperature and the second temperature by the laser beam emitted from the optical head, Magnetic domains are transferred from the recording layer to the reproducing layer by magnetostatic coupling. Then, the magnetic domain transferred to the reproducing layer is detected by being expanded by the alternating magnetic field applied by the magnetic head. The alternating magnetic field described in claim 4 is an alternating magnetic field applied from a direction perpendicular to the in-plane direction of the magneto-optical recording medium and a predetermined angle with respect to the in-plane direction of the magneto-optical recording medium. And an alternating magnetic field having

Therefore, according to the present invention, the margin of the power of the laser beam required for transferring the magnetic domain from the recording layer to the reproducing layer by magnetostatic coupling is widened, and the signal is expanded by the magnetic domain expansion. Can be played. According to a fifth aspect of the present invention, there is provided a magneto-optical disk drive for reproducing a signal from the magneto-optical recording medium according to the second aspect, wherein the temperature of the magneto-optical recording medium is set to a first temperature and a second temperature. This is a magneto-optical disk device including an optical head that irradiates a magneto-optical recording medium with a laser beam having an intensity between the two and detects the reflected light.

In the magneto-optical disk drive according to the present invention, the temperature of the magneto-optical recording medium is raised between the first temperature and the second temperature by the laser beam irradiated by the optical head, The magnetic domain of the recording layer is transferred to the first magnetic layer of the reproducing layer by magnetostatic coupling, and the magnetic domain transferred to the first magnetic layer is transferred to the second magnetic layer by exchange coupling and detected by a laser beam. The area occupied by the transfer magnetic domain in the second magnetic layer is larger than the area occupied by the transfer magnetic domain in the first magnetic layer.

Therefore, in the magneto-optical disk device according to the fifth aspect, signals can be reproduced from the magneto-optical recording medium by magnetic domain expansion using only laser light without applying a magnetic field from the outside. According to a sixth aspect of the present invention, there is provided a magneto-optical recording device including an auxiliary magnetic layer for transferring a magnetic domain from a recording layer to a reproducing layer by magnetostatic coupling and increasing a leakage magnetic field of the magnetic domain formed in the recording layer to the reproducing layer. A reproducing method for reproducing a signal from a medium, comprising: setting a magneto-optical recording medium between a first temperature at which the saturation magnetization of the recording layer is maximum and a second temperature at which the saturation magnetization of the auxiliary magnetic layer is maximum. A reproduction method characterized by reproducing a signal by irradiating a laser beam having an intensity for raising a temperature.

In the reproducing method according to the present invention, the temperature of the magneto-optical recording medium is raised between the first temperature and the second temperature by irradiating the magneto-optical recording medium with laser light. . Then, magnetic domains are transferred from the recording layer to the reproducing layer by magnetostatic coupling, and the transferred magnetic domains are detected by the laser beam. Therefore, according to the invention described in claim 6, the temperature of the magneto-optical recording medium is set to the first temperature and the second temperature.
Irradiating a laser beam having an intensity that raises the temperature to between the recording layer and the recording layer, the transfer of the magnetic domain due to the magnetostatic coupling from the recording layer to the reproducing layer easily occurs, and the signal margin can be reproduced by widening the power margin of the laser beam. .

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. Referring to FIG. 1, a magneto-optical recording medium 10 according to the present invention includes a light-transmitting substrate 1, an underlayer 2, a reproducing layer 3, an intermediate layer 4, a recording layer 5, and an auxiliary magnetic layer 6. , A protective layer 7. The translucent substrate 1 is made of glass, polycarbonate, or the like. The underlayer 2 is made of SiN, the reproducing layer 3 is made of GdFeCo, the intermediate layer 4 is made of SiN, the recording layer 5 is made of TbFeCo, the auxiliary magnetic layer 6 is made of GdFeCo, and the protective layer 7 is , SiN. Then, SiN constituting the underlayer 2 and the reproducing layer 3
GdFeCo, SiN constituting the intermediate layer 4,
TbFeCo forming the recording layer 5, GdFeCo forming the auxiliary magnetic layer 6, and SiN forming the protection layer 7
Is formed by a magnetron sputtering method.

The thickness of the underlayer 2 is 40 to 80 nm.
The thickness of the reproducing layer 3 is 20 to 40 nm, the thickness of the intermediate layer 4 is 2.5 to 20 nm, the thickness of the recording layer 5 is 30 to 100 nm, and the auxiliary magnetic layer 6, the protective layer 7 has a thickness of 10 to 100 nm.
８０80 nm. The function of the auxiliary magnetic layer 6 in the magneto-optical recording medium 10 will be described with reference to FIGS. FIG. 2 schematically shows a leakage magnetic field 51 in the reproducing layer 3 from the magnetic domain 50 of the recording layer 5 when the auxiliary magnetic layer 6 is not formed on the recording layer 5. In a magneto-optical recording medium in which the auxiliary magnetic layer 6 is not formed,
The leakage magnetic field 51 in the reproducing layer 3 is
The magnetic field 52 has the maximum distribution near the center of the magnetic domain, and the magnetic fields 53 and 54 in the direction opposite to the magnetic field 52 exist outside the magnetic domain.

On the other hand, when the auxiliary magnetic layer 6 is formed on the recording layer 5 as shown in FIG.
And the magnetic domain 60 of the auxiliary magnetic layer 6 are exchange-coupled, and the leakage magnetic field 61 from the magnetic domain 50 of the recording layer 5 in the reproducing layer 3 has the same direction as the magnetization of the magnetic domain 50 of the recording layer 5 and the magnetic domain 60 of the auxiliary magnetic layer 6. The magnetic field 62 has the maximum distribution near the center of the magnetic domain, and the magnetic fields 63 and 64 in the direction opposite to the magnetic field 62 exist outside the magnetic domain. And the magnetic field 62
Is larger than the magnetic field 52 shown in FIG.

Referring to FIG. 4, Tb forming recording layer 5
₂₀(Fe₇₅Co_{twenty five})₈₀Temperature dependence of saturation magnetization (Ms)
(○) indicates a temperature increase from room temperature to the compensation temperature of about 43 ° C.
As the temperature rises, the saturation magnetization decreases.
As the temperature rises, the saturation magnetization increases.
The sum magnetization becomes maximum. In this case, Tb₂₀(Fe₇₅C
o _{twenty five})₈₀Is the maximum saturation magnetism of 50 emu / cc at 180 ° C.
Having And, at temperatures above 180 ° C, the temperature rises
As the saturation magnetization decreases, the saturation magnetization decreases around 270 ° C.
Becomes zero. Gd constituting the auxiliary magnetic layer 6
_{twenty five}(Fe₇₅Co_{twenty five})₇₅Temperature dependence of saturation magnetization (Ms)
(●) indicates that the saturation magnetization increases as the temperature rises from room temperature.
Becomes larger, reaches a maximum around 150 ° C, and exceeds 150 ° C
At the temperature of, the saturation magnetization decreases as the temperature rises. This
Gd_{twenty five}(Fe₇₅Co_{twenty five})₇₅Is 10 at 150 ° C.
It has a maximum saturation magnetization of 2 emu / cc.

The temperature dependence of the saturation magnetization when the magnetization of the recording layer 5 and the magnetization of the auxiliary magnetic layer 6 are added is as follows.
The characteristics indicated by (□) are obtained, and the saturation magnetization becomes 120 emu / cc or more in a temperature range of 110 to 220 ° C. That is, the power of the laser beam applied to the magneto-optical recording medium fluctuates and the temperature of the magneto-optical recording medium becomes 110 to 220 ° C.
Of the saturation magnetization from the recording layer 5
mu / cc or more. This is due to the fact that the temperature at which the saturation magnetization of the recording layer 5 becomes maximum is 180 ° C. and the temperature at which the saturation magnetization of the auxiliary magnetic layer 6 becomes maximum is 150 ° C.

In general, the magnitude of the leakage magnetic field from the recording layer 5 to the reproducing layer 3 is proportional to the saturation magnetization from the recording layer 5, so that the magnitude of the leakage magnetic field is maximized at a temperature of 180 ° C. By forming the auxiliary magnetic layer 6 having the maximum saturation magnetization at a temperature different from 180 ° C., the leakage magnetic field from the recording layer 5 to the reproducing layer 3 can be increased over a wide temperature range of 110 to 220 ° C., and the power of the laser beam can be increased. Even if the temperature of the magneto-optical recording medium changes within the range of 110 to 220 ° C., each magnetic domain of the recording layer 5 can be stably transferred to the reproducing layer 3 by magnetostatic coupling. Further, since the reproduction temperature from the magneto-optical recording medium is usually in the range of 120 to 180 ° C., the above result shows that each magnetic domain of the recording layer 5 is stably transferred to the reproduction layer 3 by magnetostatic coupling at the reproduction temperature. It can be transferred.

Therefore, the auxiliary magnetic layer 6 not only increases the leakage magnetic field from the recording layer 5 to the reproducing layer 3 but also increases
It functions to increase the leakage magnetic field from the recording layer 5 to the reproducing layer 3 over a wide temperature range of 0 to 220 ° C. This means that magnetic domains are transferred from the recording layer to the reproducing layer by magnetostatic coupling,
AS-MO that detects the transferred magnetic domain by laser light
Not only standard magneto-optical recording media, but also magneto-optical recording media based on magnetic domain expansion and reproduction, in which magnetic domains are transferred from the recording layer to the reproducing layer by magnetostatic coupling, and the transferred magnetic domains are expanded by an external magnetic field and detected by laser light. Also means that a signal can be reproduced stably.

The temperature of the magneto-optical recording medium is 110 to 220 ° C.
, The saturation magnetization from the recording layer 5 is 120 em
u / cc or more, and the stray magnetic field strength from the recording layer 5 is stabilized, so that the magnetic domains of the recording layer 5 can be easily transferred to the reproducing layer 3 by magnetostatic coupling. The temperature of the medium is set to 150 ° C. at which the saturation magnetization of the auxiliary magnetic layer 6 becomes maximum, and 180 ° at which the saturation magnetization of the recording layer 5 becomes maximum.
The magneto-optical recording medium 10 is irradiated with a laser beam having a power such that the temperature is within the range of ° C. This ensures that the recording layer 5
This is because the saturation magnetic field from the source can be increased. The power of the laser beam for setting the temperature of the magneto-optical recording medium 10 in the range of 150 to 180 ° C. is such that the rotational speed of the magneto-optical recording medium 10 is 2.0.
In the case of m / s, it is 1.0 to 2.0 mW.

In the present application, the recording layer 5 is used.
TbFeCo is Tb₂₀(Fe₇₅Co _{twenty five})₈₀Not limited to T
b_x(Fe₇₅Co_{twenty five})_1-x(17 ≦ X ≦ 23at.%)
I just want it. TbFeCo having a composition in this range is:
The compensation temperature is in the range of −30 ° C. to 60 ° C .;
Has a temperature at which the saturation magnetization is maximum in the temperature range of 220 ° C
Magnetic material.

The magnetic material used for the auxiliary magnetic layer 6 in the present application is not limited to Gd ₂₅ (Fe ₇₅ Co ₂₅ ) ₇₅ ,
Gd _x (Fe ₇₅ Co ₂₅ ) _1-x (22 ≦ X ≦ 28 at.%)
Alternatively, it may be Gd _x Fe _1-x (22 ≦ X ≦ 28 at.%). GdFeCo or GdFe having a composition in this range is a magnetic material having a compensation temperature in the range of −30 ° C. to 60 ° C. and a temperature at which the saturation magnetization becomes maximum in a temperature range of 110 ° C. to 220 ° C.

Tb _x (Fe ₇₅ Co ₂₅ ) _1-x (17 ≦ X ≦ 2
3 at. _{%), Gd x (Fe 75} Co 2 5) 1-x (22 ≦ X ≦
28 at. %), And Gd _x Fe _1-x (22 ≦ X ≦ 28
at. %) By magnetron sputtering method
It is formed by changing the content of Tb or Gd mainly by controlling the RF power applied to the Tb or Gd target.

Referring to FIG. 5, a process of reproducing a signal from magneto-optical recording medium 10 using only laser light will be described. Before the laser beam irradiation, the magneto-optical recording medium 10
The reproducing layer 3 is magnetized in a fixed direction, and each magnetic domain of the recording layer 5 and each magnetic domain of the auxiliary magnetic layer 6 are magnetized in a direction based on a recording signal (see FIG. 5A). In such a state, when the laser beam LB is irradiated from the reproducing layer 3 side, the magnetic domains 50 and 60 of the recording layer 5 and the auxiliary magnetic layer 6 are irradiated.
Is the temperature (1) at which the saturation magnetization of the auxiliary magnetic layer 6 is maximized.
50 ° C.) and the temperature (18) at which the saturation magnetization of the recording layer 5 is maximized.
0 ° C.), and the leakage magnetic field 70 from the magnetic domain 50 of the recording layer 5 to the reproducing layer 3 increases. Then, a magnetic domain 30 having a magnetization 31 in the same direction as the magnetization of the magnetic domain 50 is formed in a region of the reproducing layer 3 to which the leakage magnetic field 70 reaches,
The magnetic domains 50 of the recording layer 5 are transferred to the reproducing layer 3 via the non-magnetic layer 4. Then, the transferred magnetic domain 30 is converted into a laser beam LB.
, The signal recorded on the recording layer 5 is reproduced (see FIG. 5B). Then, the laser light L
B moves, and the temperature of the domain of the magnetic domain 50 of the recording layer 5 and the domain of the magnetic domain 60 of the auxiliary magnetic layer 6 decreases, and returns to the initial state (see FIG. 5C). Therefore, the signal is reproduced from the magneto-optical recording medium 10 by using only the laser beam through the steps (A) to (C) of FIG.

A technique for reproducing a signal by using a laser beam alone to heat a predetermined area of a recording layer to a predetermined temperature or higher and transferring magnetic domains to the reproducing layer only from the heated area. Resolution reproduction method (MSR (Magnetic Su
per Resolution)), but AS-M
The magneto-optical recording medium according to the O standard reproduces signals by this method, and the magneto-optical recording medium 10 is also useful as a magneto-optical recording medium that reproduces signals by the MSR method.

With reference to FIG. 6, a description will be given of the process of the magnetic domain expansion reproduction system for reproducing a signal from the magneto-optical recording medium 10 using a laser beam and an alternating magnetic field. The process before laser beam irradiation and before the laser beam is irradiated from the reproduction layer 3 side until the magnetic domain 50 of the recording layer 5 is transferred to the reproduction layer 3 by the magnetostatic coupling via the nonmagnetic layer 4 are as follows: FIG. 5A,
This is the same as (B) (see FIGS. 6A and 6B). An alternating magnetic field Hex is applied from the outside in a state where the magnetic domain 50 of the recording layer 5 is transferred to the reproducing layer 3, and the magnetic domain of the reproducing layer 3 is applied at a timing when a magnetic field in the same direction as the magnetization of the magnetic domain 50 is applied. 30 is expanded into a magnetic domain 300, and the expanded magnetic domain 300 is detected by the laser beam LB, and a signal recorded on the recording layer 5 is reproduced. And magnetic domain 5
When the magnetic domain 300 enlarged at the timing when the magnetic field in the direction opposite to the magnetization of 0 is applied disappears and the laser beam LB also moves, the temperature of the region of the magnetic domains 50 and 60 decreases, and the initial state (FIG. 6A) Return to). Therefore, FIG.
The signal is reproduced from the magneto-optical recording medium 10 through the process of FIG.

In the above description, the temperature at which the saturation magnetization of the recording layer 5 is maximum is 180 ° C., and the temperature at which the saturation magnetization of the auxiliary magnetic layer 6 is maximum is 150 ° C. Shift the maximum temperature to a lower temperature,
By further shifting the temperature at which the saturation magnetization of the recording layer 5 becomes maximum to a higher temperature side, the temperature range at which the saturation magnetization from the recording layer 5 to which the saturation magnetization of the auxiliary magnetic layer 6 is added becomes maximum is further widened. It goes without saying that you can do it. Since the temperature at which the saturation magnetization from the magnetic material becomes maximum is determined by the composition of the magnetic material, shifting the temperature at which the saturation magnetization becomes maximum to the high temperature side or the low temperature side is performed by controlling the composition. .

The magneto-optical recording medium according to the present invention is not limited to the magneto-optical recording medium 10 shown in FIG. 1, but may be a magneto-optical recording medium 20 shown in FIG. The magneto-optical recording medium 20 corresponds to the magneto-optical recording medium 10 shown in FIG. The reproducing layer 30 includes a first magnetic layer 31 and a second magnetic layer 32. First magnetism 31 and second magnetism 31
The magnetic layer 32 is made of rare earth-rich GdFeCo, and is formed by a magnetron sputtering method. Also,
The thickness of the first magnetic layer 31 is 50 to 200 nm, and the thickness of the second magnetic layer 32 is 50 to 200 nm.

Referring to FIG. 8, the principle of reproducing a signal from the magneto-optical recording medium 20 will be described. The first magnetic layer 31 of the reproducing layer 3 is an in-plane magnetized film at room temperature and has a temperature T4 (= 1
(100 to 150 ° C.) or more, the film changes to a perpendicular magnetization film. Also,
The second magnetic layer 32 is an in-plane magnetized film at room temperature and has a temperature T2
(= 140 to 190 ° C.) or more, the film changes to a perpendicular magnetization film.
When the laser beam LB is irradiated from the reproduction layer 30 side of the magneto-optical recording medium 20, the temperature distribution becomes steep on the front side with respect to the traveling direction DR1 from the optical axis LB0 of the laser beam LB.
A broad temperature distribution is provided on the rear side of the traveling direction DR1 from B0. Then, the leakage magnetic field 70 from the magnetic domains 50 and 60 existing in the region where the temperature reaches the maximum temperature Tmax in the recording layer 5 and the auxiliary magnetic layer 6 becomes large, and the leakage magnetic field 70 becomes the second magnetic layer 32 of the reproducing layer 30. Range. Further, since the second magnetic layer 32 changes from an in-plane magnetization film to a perpendicular magnetization film at a temperature of T3 or more, a region where the temperature is T3 or more (reference numeral 321)
To 323) have a magnetization in the same direction as the magnetization of the magnetic domain 50 due to the influence of the leakage magnetic field 70 from the magnetic domain 50 of the recording layer 5. The region irradiated with the laser beam LB among the regions from 321 to 323 is denoted by 321.
To 322, the area that can be detected by the laser beam LB is the magnetic domain 320 that is the area from 321 to 322. Since the first magnetic layer 31 and the second magnetic layer 32 are exchange-coupled, the magnetic domains 320 are transferred to the first magnetic layer 31 by exchange coupling. In this case, since the temperature T4 at which the first magnetic layer 31 changes from an in-plane magnetization film to a perpendicular magnetization film and the temperature T3 at which the second magnetic layer 32 changes from an in-plane magnetization film to a perpendicular magnetization film, the magnetic domains 320 have the same sign. The image is enlarged and transferred to the area from 311 to 313. Of the regions from 311 to 313, the region irradiated with the laser beam LB is the region from 311 to 312, and the regions that can be detected by the laser beam LB are 311 and 312. The magnetic domain 310 is enclosed. Therefore, the magnetic domains 320 are enlarged and transferred to the magnetic domains 310. Then, the magnetic domain 310 has the laser light L
The signal recorded on the recording layer 5 is reproduced by being detected by B.

Referring to FIG. 9, a process of reproducing a signal from the magneto-optical recording medium 20 will be described. Before the laser beam irradiation, the first magnetic layer 31 and the second magnetic layer 32 of the reproducing layer 30 maintain the in-plane magnetization, and each magnetic domain of the recording layer 5 and each magnetic domain of the auxiliary magnetic layer 6 are based on a recording signal. (See FIG. 9A). In such a state, when the laser beam LB is irradiated from the reproduction layer 30 side, as shown in FIG.
The magnetic domain 50 of the recording layer 5 is enlarged and transferred as the magnetic domain 310 to the first magnetic layer 31 of the reproducing layer 30 according to the principle described with reference to FIG. 9, and the magnetic domain 310 is detected by the laser beam LB (see FIG. 9B). ). Thus, the signal recorded on the recording layer 5 is reproduced. After that, the laser beam LB moves, and the temperature of the magnetic domain 50 of the recording layer 5 and the temperature of the domain of the magnetic domain 60 of the auxiliary magnetic layer 6 decrease, thereby returning to the initial state (see FIG. 9C). Therefore, a signal is reproduced from the magneto-optical recording medium 20 through the steps (A) to (C) of FIG.

As is apparent from FIG. 9, the magneto-optical recording medium 20 reproduces each magnetic domain of the recording layer 5 by controlling the temperature distribution of each layer by the laser beam LB without applying an alternating magnetic field from the outside. This is a magneto-optical recording medium capable of reproducing a signal by being enlargedly transferred to the layer 30. With reference to FIG. 10, a description will be given of a magneto-optical disk device that reproduces signals from the magneto-optical recording media 10 and 20. The magneto-optical disk device 200 includes an optical head 100, a reproduction signal amplification circuit 110, an external synchronization signal generation circuit 120, a servo circuit 130, a servo mechanism 140, a spindle motor 150, a comparator 160, a demodulation circuit 170 , A control circuit 180, a drive signal generation circuit 190, and a laser drive circuit 220.

The optical head 100 irradiates a laser beam to the magneto-optical recording media 10 and 20, and detects the reflected light. The reproduction signal amplification circuit 110 amplifies the focus error signal, the tracking error signal, the optical signal, and the magneto-optical signal detected by the optical head 100 to predetermined levels, and outputs the focus error signal and the tracking error signal to the servo circuit 130. And outputs the optical signal to the external synchronization signal generation circuit 1.
20 and the magneto-optical signal to the comparator 160.

The external synchronizing signal generation circuit 120 generates an external synchronizing signal based on the input optical signal, and outputs the generated external synchronizing signal to the servo circuit 130 and the comparator 16.
0 and output to the demodulation circuit 170. Here, the optical signal is an optical signal obtained by detecting a shape formed at a constant period on the magneto-optical recording medium 10 or 20, and when the magneto-optical recording medium 10 or 20 is a land / groove type magneto-optical recording medium. Is an optical signal that detects a wobble formed on a groove wall, and in the case of a magneto-optical recording medium having a servo area, is an optical signal that detects a pit formed in the servo area at a constant period. The external synchronizing signal generation circuit 120 of the present application includes an external synchronizing signal based on not only the optical signal based on the wobbles and pits described above but also all the optical signals that detect the shape formed on the magneto-optical recording medium at a constant period. Is intended to be included.

The servo circuit 130 includes the reproduction signal amplification circuit 1
The servo mechanism 140 is controlled to perform focus servo and tracking servo of an objective lens (not shown) in the optical head 100 based on the focus error signal and the tracking error signal input from the external synchronization signal generation circuit 120. The spindle motor 150 is rotated at a predetermined rotation speed based on the external synchronization signal thus generated. The servo mechanism 140 performs focus servo and tracking servo of an objective lens (not shown) in the optical head 100 based on control from the servo circuit 130. The spindle motor 150 rotates the magneto-optical recording medium 10 or 20 at a predetermined rotation speed under the control of the servo circuit 130.

The comparator 160 synchronizes the magneto-optical signal input from the reproduction signal amplifying circuit 110 at a predetermined level in synchronization with the external synchronizing signal input from the external synchronizing signal generating circuit 120. The demodulation circuit 170 demodulates the compared magneto-optical signal in synchronization with the external synchronization signal input from the external synchronization signal generation circuit 120, and outputs the demodulated magneto-optical signal to the external output device as reproduction data.

The control circuit 180 includes the drive signal generation circuit 19
Control 0. The drive signal generation circuit 190 generates a drive signal for causing the optical head 100 to irradiate the magneto-optical recording medium 10 or 20 with laser light of a predetermined intensity, and outputs the generated drive signal to the laser drive circuit 220. The laser drive circuit 220 drives a semiconductor laser (not shown) in the optical head 100 based on a drive signal from the drive signal generation circuit 190. The optical head 100 irradiates the magneto-optical recording medium 10 or 20 with laser light having a predetermined intensity.

When the magneto-optical recording media 10 and 20 are mounted on the magneto-optical disk device 200, the control circuit 180 controls the servo circuit 130 to rotate the spindle motor 150 at a predetermined rotation speed. The spindle motor 150 is rotated at a predetermined rotation speed. Further, the control circuit 180 determines that the magneto-optical recording media 10 and 20 are
Drive signal generation circuit for generating a drive signal LBGS for generating a laser beam having a power whose temperature is increased between a temperature at which the saturation magnetization of the recording layer 5 becomes maximum and a temperature at which the saturation magnetization of the recording layer 5 becomes maximum. 190 to control the driving signal generation circuit 1
90 generates LBGS for the drive signal, and outputs the laser drive circuit 2
Output to 20. The laser drive circuit 220 drives a semiconductor laser (not shown) in the optical head 100 based on the drive signal LBGS from the drive signal generation circuit 190, and the optical head 100 outputs the laser beam having the above power to the magneto-optical recording medium 10. Or 20 is irradiated, and the reflected light is detected. The focus error signal and the tracking error signal detected by the optical head 100 are transmitted to the servo circuit 1 via the reproduction signal amplifier circuit 110 as described above.
The focus servo and tracking servo of an objective lens (not shown) in the optical head 100 are performed. The optical signal detected by the optical head 100 is transmitted to the reproduction signal amplification circuit 11 as described above.
0 to the external synchronization signal generation circuit 120, the external synchronization signal generation circuit 120 generates an external synchronization signal based on the optical signal, and outputs the generated external synchronization signal to the servo circuit 130, the comparator 160, and the demodulation circuit. Output to 170. Then, the servo circuit 130 rotates the spindle motor 150 at a predetermined rotation speed in synchronization with the input external synchronization signal.

The magneto-optical signal detected by the optical head 100 from the data areas of the magneto-optical recording media 10 and 20 is supplied to the comparator 16 via the reproduction signal amplifying circuit 110.
The signal is input to 0 and is binarized by the comparator 160 in synchronization with the external synchronization signal, and is input to the demodulation circuit 170. In the demodulation circuit 170, the binarized magneto-optical signal is demodulated in synchronization with the external synchronization signal input from the external synchronization signal generation circuit 120, and is output to the external output device as reproduction data.

With the above operation, the signal is reproduced from the magneto-optical recording medium 10 using only the laser light, and the signal is reproduced from the magneto-optical recording medium 20 using only the laser light in a magnetic domain enlarged reproduction. With reference to FIG. 11, a description will be given of a magneto-optical disk device for reproducing signals from the magneto-optical recording medium 10 by the magnetic domain expansion reproduction method. FIG.
19, a magnetic head drive circuit 210 and a magnetic head 230 are added to the magneto-optical disk device 200 shown in FIG.

In the magneto-optical disk device 400, the drive signal generation circuit 190 generates a drive signal HEX for the magnetic head 230 to apply an alternating magnetic field to the magneto-optical recording medium 10.
GS and the magneto-optical recording media 10 and 20 generate laser light having a power that is raised between the temperature at which the saturation magnetization of the auxiliary magnetic layer 6 is maximized and the temperature at which the saturation magnetization of the recording layer 5 is maximized. Drive signal LBGS to output the drive signal HEXGS to the magnetic head drive circuit 210 and the drive signal LBGS to the laser drive circuit 220. The operation in which the laser drive circuit 220 drives the semiconductor laser (not shown) in the optical head 100 based on the drive signal LBGS is the same as that described in FIG. The magnetic head drive circuit 210 receives the drive signal H from the drive signal generation circuit 190.
The magnetic head 230 is driven based on EXGS, and the magnetic head 230 applies an alternating magnetic field to the magneto-optical recording medium 10.

The magneto-optical recording medium 10 is mounted on the magneto-optical disk device 400, and the rotation of the magneto-optical recording medium 10, the irradiation of laser light having the above power from the optical head 100,
The operation until the focus servo and tracking servo of the objective lens (not shown) in the optical head 100 are performed is the same as that described with reference to FIG. After that, the control circuit 180 controls the drive signal generation circuit 190 to generate the drive signal HEXGS, and the drive signal generation circuit 190
Generates a drive signal HEXGS. Then, it outputs the generated drive signal HEXGS to the magnetic head drive circuit 210. Then, the magnetic head drive circuit 210 outputs the drive signal H
The magnetic head 230 is driven based on EXGS, and the magnetic head 230 applies an alternating magnetic field to the magneto-optical recording medium 10. Then, a magneto-optical signal is detected from the magneto-optical recording medium 10 by magnetic domain expansion reproduction through the process described with reference to FIG. The detected magneto-optical signal is input to the comparator 160 via the reproduction signal amplification circuit 110,
The data is binarized by the comparator 160 in synchronization with the external synchronization signal from the external synchronization signal generation circuit 120. Then, the binarized magneto-optical signal is input to the demodulation circuit 170, demodulated by the demodulation circuit 170, and output to an external output device as reproduction data. This completes the operation of magnetic domain expansion reproduction from the magneto-optical recording medium 10 using the laser light and the alternating magnetic field.

Magnetic head 2 of magneto-optical disk drive 400
The alternating magnetic field applied to the magneto-optical recording medium 10 from 30 includes an alternating magnetic field perpendicular to the in-plane direction of the magneto-optical recording medium 10 and a predetermined magnetic field in the in-plane direction of the magneto-optical recording medium 10. An alternating magnetic field having an angle. FIG. 12, 1
With reference to FIG. 3, a description will be given of a mechanism in which an alternating magnetic field having a predetermined angle with respect to the in-plane direction of the magneto-optical recording medium 10 is applied and the magnetic domain is enlarged and reproduced from the magneto-optical recording medium 10.
Referring to FIG. 12, magnetic domains having magnetizations in directions opposite to each other are formed in recording layer 5 and auxiliary magnetic layer 6.
Are initialized to have a certain direction of magnetization. At one edge 513 of the magnetic domain 50 of the recording layer 5, a leakage magnetic field 509 including an in-plane component exists, and the magnetic domain 50
A leakage magnetic field 510 including a component in the in-plane direction exists at the other edge 514 of. A first alternating magnetic field Hex1 is applied to one edge 513, and a second alternating magnetic field Hex1 is applied to the other edge 514.
The magnetic domain expansion reproduction is performed by applying the alternating magnetic field Hex2 of FIG. In this case, the laser light LB is applied to one edge 513 or the other edge 514. First alternating magnetic field Hex
1 comprises a magnetic field component 501 and a magnetic field component 502, and a second alternating magnetic field Hex2 comprises a magnetic field component 505 and a magnetic field component 5
06.

The magnetic field component 501 further includes a component 504 in a direction perpendicular to the recording layer 5 and a component 5 in a direction horizontal to the recording layer 5.
03, and the direction of the component 503 is
Is the same as the direction of the in-plane component. Therefore, the magnetic field component 50
Reference numeral 1 denotes a magnetic field component including a component that increases the intensity of the in-plane component of the leakage magnetic field 509. The magnetic field component 505 further includes a component 508 in a direction perpendicular to the recording layer 5 and a component 507 in a direction horizontal to the recording layer 5, and the direction of the component 507 is the direction of the in-plane component of the leakage magnetic field 510. Is the same as Therefore, the magnetic field component 505 is a magnetic field component that includes a component that increases the strength of the in-plane component of the leakage magnetic field 510.

Accordingly, by applying the first alternating magnetic field Hex1 to one edge 513 and applying the second alternating magnetic field Hex2 to the other edge 514, the transfer of the magnetic domain from both ends of the magnetic domain 50 to the reproducing layer 3 is performed. Enlargement can be caused, and a reproduced signal corresponding to the domain length of the magnetic domain 50 can be obtained. In this case, by applying the alternating magnetic field Hex1, not only the in-plane component of the leakage magnetic field 509 but also the vertical component of the leakage magnetic field 509 can be increased. Further, by applying the alternating magnetic field Hex2, not only the in-plane component of the leakage magnetic field 510 but also the vertical component of the leakage magnetic field 510 can be increased. As a result, the transfer and expansion of magnetic domains from the recording layer 5 to the reproducing layer 3 are likely to occur.

Referring to FIG. 13, a first alternating magnetic field Hex
The principle that each magnetic domain of the recording layer 5 is easily transferred to the reproducing layer 3 when the first and second alternating magnetic fields Hex2 are applied will be described. As shown in FIG. 13A, when a signal is reproduced, the magnetization of the reproduction layer 3 is initialized in a fixed direction. In the recording layer 5, signals are recorded, and the magnetic domains 50, 51,
52 exist. In this case, the intensity distribution of the leakage magnetic field in the direction perpendicular to the magnetic domain 50, that is, in the direction toward the reproducing layer 3, is shown in FIG.
3 (B). On the other hand, the intensity distribution of the leakage magnetic field in the in-plane direction of the magnetic domain 50 is as shown in FIG. That is, there is a stray magnetic field having the same strength in opposite directions at both ends of the magnetic domain 50, and the magnetic domain 51 and the magnetic domain 50 are present.
If the leakage magnetic field at the boundary between the magnetic domain 50 and the magnetic domain 51 is directed toward the magnetic domain 51, the leakage magnetic field at the boundary between the magnetic domain 50 and the magnetic domain 52 is directed from the magnetic domain 50 to the magnetic domain 52. Therefore, the leakage magnetic field acting on the reproducing layer 3 in the in-plane direction from the magnetic domain 50 is:
Since the directions are opposite and the strengths are the same, the magnetic force acting to reverse the magnetization of the reproducing layer 3 to the direction of the magnetization of the magnetic domain 50 is balanced at both ends of the magnetic domain 50. As a result, magnetic domain 5
No preferential transfer of magnetic domains to the reproducing layer 3 from one end of 0 occurs.

However, when a magnetic field including a magnetic field component in the in-plane direction is applied to the magnetic domain 50, the intensity distribution of the leakage magnetic field in the in-plane direction from the magnetic domain 50 becomes a distribution as shown in FIG. When a magnetic field directed from the magnetic domain 50 toward the magnetic domain 51 is applied, the leakage magnetic field 5 at the boundary between the magnetic domain 50 and the magnetic domain 51 is increased.
17 is stronger than the leakage magnetic field 518 at the other boundary. Accordingly, the leakage magnetic field 515 acts on the magnetic domain 516 of the reproducing layer 3 corresponding to the end of the magnetic domain 50 on the magnetic domain 51 side, and the magnetic domain 516
Is easily reversed in the same direction as the magnetization of the magnetic domain 50. As a result, the transfer of the magnetic domain 50 to the reproducing layer 3 is performed by the magnetic domain 51.
A seed domain having a magnetization in the same direction as the magnetization of the magnetic domain 50 is generated in the magnetic domain 516 of the reproducing layer 3 in a direction perpendicular to the reproducing layer 3 and in the same direction as the magnetization of the magnetic domain 50. The seed magnetic domain is expanded by applying the magnetic field of.

As described above, when a magnetic field including a magnetic field component in the in-plane direction is applied, transfer to the reproducing layer is promoted. Referring again to FIG. 12, the first alternating magnetic field Hex1 is
09, 512 are applied to the boundary of the magnetic domain where the leakage magnetic field having the same polarity exists, and the second alternating magnetic field Hex2 is applied to the leakage magnetic field 51.
A magnetic domain expansion reproduction is performed by applying the magnetic field to the boundary of the magnetic domain in which the leakage magnetic field having the same polarity as that of 0, 511 exists.

Referring to FIG. 14, transfer of magnetic domains from both ends of each magnetic domain formed on recording layer 5 of magneto-optical recording medium 10 is performed.
A specific mode of signal detection resulting from the enlargement will be described. The magnetic head 230 includes a core 231 and a coil 232 wound around the core 231, and can generate a first alternating magnetic field Hex1 from the edge 233 of the core 231 by changing the direction of a current flowing through the coil 232. The second alternating magnetic field Hex2 can be generated from the edge 234 of the core 231.

At the edge 520 of the magnetic domain 519, a leakage magnetic field 521 containing an in-plane component exists, and at the edge 523, a leakage magnetic field 522 containing an in-plane component exists. In addition, a leakage magnetic field 526 including an in-plane component exists at an edge 525 of the magnetic domain 524, and a leakage magnetic field 528 including an in-plane component exists at the edge 527. And FIG.
As described with reference to FIG. 2, the first alternating magnetic field Hex1
Contains a magnetic field component that increases the strength of the in-plane components of the leakage magnetic fields 522 and 526, and the second alternating magnetic field Hex2
21 and 528 include a magnetic field component for increasing the intensity of the in-plane component. Therefore, the first alternating magnetic field Hex1 and the laser beam LB1
Thus, the magnetic domain 519 can be transferred and expanded from the edge 523 side to the reproducing layer 3 via the nonmagnetic layer 4 and detected.
Is transferred from the edge 525 side to the reproducing layer 3 via the nonmagnetic layer 4 and detected. Also, the second alternating magnetic field Hex
2 and the laser beam LB2 to form a magnetic domain 519 at an edge 520.
The magnetic domain 524 can be transferred and expanded from the edge 527 to the reproducing layer 3 via the non-magnetic layer 4 and detected.

In the present application, first, a laser beam LB1 is applied to a region to which the first alternating magnetic field Hex1 is applied.
Each magnetic domain is transferred and expanded to the reproducing layer 3 from an edge where a leakage magnetic field having the same polarity as the leakage magnetic fields 522 and 526 is generated, and a magneto-optical signal is detected. Thereafter, the laser beam LB1 is moved to a region to which the second alternating magnetic field Hex2 is applied (referred to as "LB2" in the sense of the moved laser beam), and the laser beam LB2 is leaked by the second alternating magnetic field Hex2 and the laser beam LB2. Magnetic field 521,
Each magnetic domain is transferred and expanded to the reproducing layer 3 from the edge where a leakage magnetic field having the same polarity as 528 occurs, and a magneto-optical signal is detected. Therefore, the magneto-optical signal from the edge of each magnetic domain is detected independently.

In this case, the laser beam LB1 is irradiated so that the optical axis L01 of the laser beam LB1 coincides with an edge that generates a leakage magnetic field having the same polarity as the leakage magnetic fields 522 and 526, and the optical axis of the laser beam LB2 is The laser beam LB2 is irradiated so as to coincide with an edge that generates a leakage magnetic field having the same polarity as that of the laser beam LB2. Therefore, the distance L for moving the laser light in the track direction DR2 is an integral multiple of the unit magnetic domain length. This is because each magnetic domain length is an integral multiple of the unit magnetic domain length. The length CL of the core 231 of the magnetic head 230 in the track direction DR2 is shorter than the distance L for moving the laser beam in the track direction DR2, and the first alternating magnetic field H
When ex1 is applied to the edge where the leakage magnetic field 522 exists, the length is such that the second alternating magnetic field Hex2 is applied to the edge where the leakage magnetic field 522 exists.

A first alternating magnetic field Hex1 having a predetermined angle with respect to the in-plane direction of the magneto-optical recording medium 10;
The magneto-optical disk device 400 shown in FIG. 11 is also used in the case of applying the alternating magnetic field Hex2 to the magneto-optical recording medium 10 to perform magnetic domain expansion reproduction. Referring to FIG. 15, magneto-optical recording medium 10 in magneto-optical disk device 200 shown in FIG.
Alternatively, the flowchart of the signal reproduction from 20 will be described. When signal reproduction starts (step S1),
When the temperature of the magneto-optical recording medium 10 or 20 is between the temperature T1 at which the saturation magnetization of the auxiliary magnetic layer 6 becomes maximum and the temperature T2 at which the saturation magnetization of the recording layer 5 becomes maximum, magneto-optical recording is performed. The medium 10 or 20 is irradiated (step S2), a magneto-optical signal is detected from the magneto-optical recording medium 10, a magneto-optical signal is detected from the magneto-optical recording medium 20 by magnetic domain expansion (step S3), and the reproduction is completed (step S3). Step S4).

Referring to FIG. 16, a flowchart of magnetic domain expansion reproduction from magneto-optical recording medium 10 in magneto-optical disk device 400 shown in FIG. 11 will be described. When the signal reproduction is started (step S1), the power of the magneto-optical recording medium 10 is changed between the temperature T1 at which the saturation magnetization of the auxiliary magnetic layer 6 becomes maximum and the temperature T2 at which the saturation magnetization of the recording layer 5 becomes maximum. Is irradiated on the magneto-optical recording medium 10 (step S2), and an alternating magnetic field is applied to the magneto-optical recording medium 10 (step S3).
Signal is detected by the magnetic domain expansion (step S
4), the reproduction ends (step S5). In step S3, if an alternating magnetic field having a predetermined angle with respect to the in-plane direction of the magneto-optical recording medium 10 is applied to the magneto-optical recording medium 10, the above-described first alternating magnetic field Hex
1 and the second alternating magnetic field Hex2
0 is applied.

[Brief description of the drawings]

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

FIG. 2 is a diagram schematically showing a leakage magnetic field from a single recording layer of the magneto-optical recording medium shown in FIG.

FIG. 3 is a diagram schematically showing a leakage magnetic field from a recording layer and an auxiliary magnetic layer of the magneto-optical recording medium shown in FIG.

FIG. 4 is a diagram showing the temperature dependence of the saturation magnetization of GdFeCo, the saturation magnetization of TbFeCo, and the sum thereof.

FIG. 5 is a diagram showing a process of reproducing a signal from the magneto-optical recording medium shown in FIG. 1 using only a laser beam.

FIG. 6 is a diagram showing a process of reproducing a signal from the magneto-optical recording medium shown in FIG. 1 using a laser beam and an alternating magnetic field.

FIG. 7 is another sectional structural view of the magneto-optical recording medium according to the present invention.

FIG. 8 is a diagram for explaining the principle of signal reproduction from the magneto-optical recording medium shown in FIG.

9 is a diagram for explaining a process of reproducing a signal from the magneto-optical recording medium shown in FIG.

FIG. 10 is a block diagram of a magneto-optical disk drive according to the present invention.

FIG. 11 is another block diagram of the magneto-optical disk drive according to the present invention.

FIG. 12 is a diagram for explaining the principle of performing magnetic domain expansion reproduction by applying an alternating magnetic field having a predetermined angle with respect to the in-plane direction of the magneto-optical recording medium.

FIG. 13 is a diagram for explaining that when an alternating magnetic field having a predetermined angle with respect to the in-plane direction of the magneto-optical recording medium is applied, magnetic domains in the recording layer are easily transferred to the reproducing layer.

FIG. 14 is a diagram illustrating a specific mode in the case where an alternating magnetic field having a predetermined angle with respect to the in-plane direction of the magneto-optical recording medium is applied to perform magnetic domain expansion reproduction.

15 is a flowchart of a signal reproducing method in the magneto-optical disk device shown in FIG.

16 is a flowchart of a signal reproducing method in the magneto-optical disk device shown in FIG.

[Explanation of symbols]

Reference Signs List 1 translucent substrate, 2 underlayer, 3, 30 reproducing layer, 4
Non-magnetic layer, 5 recording layer, 6 auxiliary magnetic layer, 7 protective layer, 10, 20 magneto-optical recording medium, 30, 50, 60,
300, 310, 320 magnetic domains, 51, 52, 53, 5
4, 61, 62, 63, 64, 70, 509, 510,
511, 512 Leakage magnetic field, 31 magnetization, 100 optical head, 110 reproduction signal amplification circuit, 120 external synchronization signal generation circuit, 130 servo circuit, 140 servo mechanism, 150 spindle motor, 160 comparator, 170 demodulation circuit, 180 control circuit, 190 Drive signal generation circuit, 200 magneto-optical disk drive, 210
Magnetic head drive circuit, 220 laser drive circuit, 23
0 magnetic head, 231 core, 232 coil, 23
3, 234 edge, 400 magneto-optical disk drive, 5
13, 514 edge

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) G11B 11/105 586 G11B 11/105 586K 586M (72) Inventor Hiroki Ishida 2-chome Keihanhondori, Moriguchi-shi, Osaka 5-5 Sanyo Electric Co., Ltd. (72) Inventor ▲ Naoyuki Taka 2-5-5 Keihanhondori, Moriguchi City, Osaka Prefecture Sanyo Electric Co., Ltd. (72) Inventor Kenichiro Mitani Moriguchi City, Osaka Prefecture 2-5-5 Keihanhondori Sanyo Electric Co., Ltd. F-term (reference) 5D075 AA03 CC11 CD11 FF04 FF12

Claims (6)

[Claims] 1. A magneto-optical recording medium for transferring magnetic domains from a recording layer to a reproducing layer by magnetostatic coupling, comprising: an auxiliary magnetic layer for increasing a leakage magnetic field of the magnetic domains formed in the recording layer to the reproducing layer; The recording layer has a first temperature at which the saturation magnetization is maximum, the auxiliary magnetic layer has a second temperature at which the saturation magnetization is maximum, and the first temperature and the second temperature. A magneto-optical recording medium characterized by different temperatures. 2. The reproducing layer has a first magnetic layer having a first transition temperature that changes from an in-plane magnetization film to a perpendicular magnetization film, and a second transition temperature that changes from an in-plane magnetization film to a perpendicular magnetization film. A second magnetic layer, wherein the first magnetic layer is formed on the recording layer side, and the second magnetic layer is formed on the opposite side to the recording layer and in contact with the first magnetic layer; 2. The magneto-optical recording medium according to claim 1, wherein the second transition temperature is lower than the first transition temperature. 3. The recording layer has a compensation temperature of −30 ° C. to 6 ° C.
2. The auxiliary magnetic layer is made of GdFeCo or GdFe having a compensation temperature in a range of −30 ° C. to 60 ° C. 3.
Alternatively, the magneto-optical recording medium according to claim 2. 4. A magneto-optical disk device for reproducing a signal from a magneto-optical recording medium according to claim 1, wherein: a magnetic head for applying an alternating magnetic field to the magneto-optical recording medium; and a temperature of the magneto-optical recording medium. Are the first temperature and the second
An optical head for irradiating the magneto-optical recording medium with a laser beam having an intensity between the above-mentioned temperatures and detecting reflected light thereof. 5. A magneto-optical disk device for reproducing a signal from the magneto-optical recording medium according to claim 2, wherein the temperature of the magneto-optical recording medium is equal to the first temperature and the second temperature.
A magneto-optical disc device including an optical head for irradiating the magneto-optical recording medium with a laser beam having an intensity between the above-mentioned temperatures and detecting reflected light. 6. A signal from a magneto-optical recording medium including an auxiliary magnetic layer that transfers a magnetic domain from a recording layer to a reproducing layer by magnetostatic coupling and increases a leakage magnetic field of the magnetic domain formed in the recording layer to the reproducing layer. And reproducing the magneto-optical recording medium between a first temperature at which the saturation magnetization of the recording layer is maximum and a second temperature at which the saturation magnetization of the auxiliary magnetic layer is maximum. A reproducing method characterized by reproducing a signal by irradiating a laser beam having an intensity for raising a temperature.