JP2001195792A - Magneto-optical recording medium and reproducing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deficiency of resolution and the generation of noise factor in the reproduction which are caused by the generation of the transfer even in a zone unnecessary for the transfer of recording magnetic domain. SOLUTION: This magneto-optical recording medium is provided with a recording layer 5, on which information is recorded in the magnetization direction vertical to the film surface, a reproducing layer 3, on which the information recorded on the recording layer 5 is transferred to be formed as the reproducing magnetic domain in the magnetization direction vertical to the film surface by the magnetic coupling and a transfer control layer 6 magnetically coupled with the recording layer 5, the magnetization direction of the recording layer 5 is opposed to the magnetization direction of the transfer control layer 6 corresponding to the recording layer 5 in the temperature range below the temperature, at which the reproducing magnetic domain is transferred on the reproducing layer 3, and the temperature of the transfer control layer 6 is equal to or above the Curie temperature in the temperature range equal to or above the transferring temperature.

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 and reproducing information by a laser beam utilizing a magneto-optical effect, and a reproducing method therefor. The present invention relates to a magneto-optical recording medium and a reproducing method thereof.

[0002]

2. Description of the Related Art In magneto-optical recording, which is a high-density rewritable recording / reproducing method, a part of a laminated magnetic film (recording film structure) of a magneto-optical recording medium is locally cured by irradiating a laser beam. The information signal is recorded by heating to a temperature higher than the temperature or the compensating composition temperature, and forming a recording magnetic domain with an external magnetic field in a predetermined portion of the magnetic film included in the recording film structure, and reading this information using the magneto-optical effect. .

[0003] As one of the magneto-optical recording methods for such a magneto-optical recording medium, a laser beam of a constant intensity is irradiated by a semiconductor laser or the like to raise the temperature of the recording magnetic film as a whole, and then perform recording. There is a magnetic field modulation recording system in which thermomagnetic recording is performed on a predetermined portion using an external magnetic field whose direction is modulated according to a signal. Further, as another recording method, while applying an external magnetic field of a constant intensity, a laser beam intensity-modulated according to a recording signal is irradiated to raise the temperature of a predetermined portion of the recording magnetic film to thereby increase the external magnetic field. There is an optical modulation recording system that performs thermomagnetic recording in the direction of.

In reproducing a recording signal, when a laser beam (reproducing light) whose polarization direction is aligned in one direction is condensed on a magneto-optical recording medium, the magneto-optical effect of the magneto-optical recording medium causes the recording magnetic domain to be formed. The direction of the magnetization is detected as rotation of the polarization direction of the reflected light or transmitted light. Thereby, the recorded information signal is reproduced.

However, in the conventional magneto-optical recording medium, when the size of the recording magnetic domain becomes smaller than the size of the light spot (reproducing light spot) of the reproducing light on the magneto-optical recording medium, not only the recording magnetic domain to be reproduced but also the recording magnetic domain becomes small. The recording magnetic domains located before and after that are included in the reproduction light spot (that is, the detection range). For this reason, the reproduced signal becomes small due to interference from the recording magnetic domains, and S
Problems such as a decrease in the / N ratio or no output of the reproduction signal occur.

In order to solve this problem, a magneto-optical recording system using magnetic super-resolution has been proposed, in which a reproduction signal is read from a partial area of a reproduction light spot.

(I) A magneto-optical recording / reproducing method using a magnetic super-resolution called a double mask method, which is one of the magnetic super-resolution methods, will be briefly described below.

FIG. 12 shows a structure at the time of reproduction by the double mask system. FIG. 12A is a plan view showing a part of a track of the magneto-optical recording medium 60 in the conventional double mask system. b) shows the magneto-optical recording medium 60
FIG. 3 is a cross-sectional view showing the configuration (particularly, the direction of magnetization) of the recording film structure of FIG.

As shown in the sectional view of FIG.
The recording film structure of the magneto-optical recording medium 60 includes a reproducing layer 63, a reproducing auxiliary layer 64, an intermediate layer 65, and a recording layer 66 which are sequentially stacked on a substrate (not shown). FIG.
The arrow 160 shown in (b) is the moving direction along the track of the magneto-optical recording medium 60, and the arrows drawn in each of the layers 63 to 66 indicate the direction of magnetization at each location.

The conventional magneto-optical recording medium 60 comprises a reproducing magnetic field generating means 61 applied to a region of a reproducing light spot 67.
And the initialization magnetic field generation means 62 located in front of the reproduction magnetic field generation means 61 in the moving direction 160. In the following, reference numerals 61 and 62 are used for the reproducing magnetic field generated by the reproducing magnetic field generating means 61 and the initialization magnetic field generated by the initializing magnetic field generating means 62, respectively.

The reproduction operation of the double-mask type magneto-optical recording medium 60 thus configured will be described.

First, a signal (information) is thermomagnetically recorded in the recording layer 66 as a recording magnetic domain 69 in advance. Before the laser beam is applied during reproduction, the direction of magnetization of the reproduction layer 63 is aligned with the direction of the initialization magnetic field 62. During reproduction, as shown in FIG. 12A, a reproducing laser beam is irradiated to the rotating magneto-optical recording medium 60 to form a reproduction light spot 67, and the temperature of the recording film structure is raised. As a result, a temperature distribution as shown in FIG. 12A is generated on the magneto-optical recording medium 60, and a low-temperature region 71, a high-temperature region 72, and an intermediate temperature region 70 are formed.

The direction of magnetization of the reproducing layer 63 is determined by the intermediate layer 65 in the low-temperature region 71 near room temperature.
Since the exchange coupling between the magnetic field and the recording layer 66 is interrupted, they are aligned in the direction of the initialization magnetic field 62. In the intermediate temperature region 70, the coercive force of the reproducing layer 63 decreases as the temperature rises due to the irradiation of the reproducing laser beam, and the intermediate layer 65 moves from the in-plane magnetic film having in-plane magnetic anisotropy to the perpendicular magnetic field. The transition to the anisotropic perpendicular magnetization film makes the exchange coupling between the reproduction layer 63 and the recording layer 66 dominant, and the magnetization direction of the reproduction layer 63 is aligned with the magnetization direction of the recording layer 66.

Further, the Curie temperature Tc of the reproduction assisting layer 64
In the high temperature region 72 described above, since the magnetization of the reproduction auxiliary layer 64 disappears, the exchange coupling between the reproduction layer 63 and the intermediate layer 65 and the recording layer 66 is interrupted, and the reproduction layer 63 having a small coercive force is cut off. The magnetization is aligned with the direction of the reproducing magnetic field 61.
Therefore, both the low-temperature region 71 and the high-temperature region 72 inside the reproduction light spot 67 mask the recording magnetic domain 69, and information is reproduced only from the recording magnetic domain 69 existing in the intermediate temperature region 70 through reflected light. It can be read as a signal.

Here, the direction of the reproducing magnetic field 61 is opposite to the direction of the initializing magnetic field 62. Then, the reproduction light spot 67
, The temperature of the recording layer 66 decreases again, and the recording layer 66 and the reproducing layer 63 return to a state where they are cut off by the intermediate layer 65.

According to such a magneto-optical recording medium 60,
Even if the recording magnetic domain 69 is smaller than the reproducing light spot 67, it is possible to reproduce recorded information at high density without causing interference from the preceding and following recording magnetic domains 69.

However, in the above-described magneto-optical recording medium 60,
There is a disadvantage that an initialization magnetic field 62 or a reproducing magnetic field 61 is required to align the magnetization direction of the reproducing layer 63 in one direction.

Therefore, a reproducing method using magnetic super-resolution for solving the above-mentioned disadvantage has been proposed.

Hereinafter, a method proposed in Japanese Patent Application Laid-Open No. 5-81717 will be described with reference to FIGS. 13A and 13B as one method that does not require an initializing magnetic field and a reproducing magnetic field. I do. FIG. 13A is a plan view showing a part of a track of the magneto-optical recording medium 80 disclosed in the above publication, and FIG. 13B is a diagram showing a configuration of a recording film structure of the magneto-optical recording medium 80 (particularly, FIG. FIG. 3 is a cross-sectional view illustrating a direction of magnetization).

As shown in the sectional view of FIG. 13B, the magneto-optical recording medium 80 has a recording film structure including a reproducing layer 83 and a recording layer 85 formed on a substrate (not shown). An intermediate layer 84 is provided between the reproducing layer 83 and the recording layer 85. An arrow 180 shown in FIG. 13A is a moving direction of the magneto-optical recording medium 80 along a track.
The arrows drawn in each of the layers 83 and 85 in FIG. 13B indicate the direction of magnetization at each location. In the magneto-optical recording medium 80, the magneto-optical recording medium 6 described above is used.
Unlike the recording layer 83, a magnetic film having in-plane magnetic anisotropy at room temperature is used as the reproducing layer 83.

Similarly to the magneto-optical recording medium 60, when reproducing information from the magneto-optical recording medium 80, a reproducing laser beam is irradiated to form a reproducing light spot 87. When the reproducing laser beam is applied to the rotating magneto-optical recording medium 80, the temperature distribution of the recording film structure including the reproducing layer 83 and the recording layer 85 is not rotationally symmetric with respect to the center of the circle of the reproducing light spot 87. However, the irradiated portion of the reproduction light spot 87 and the reproduction light spot 87
Is a high temperature region 90. A portion outside the high-temperature region 90 and included in the reproduction light spot 87 becomes a low-temperature region 91.

The magneto-optical recording medium 80 thus configured
Will be described.

The recording signal is recorded in the recording layer 85 in advance as a recording magnetic domain 89 smaller than the reproducing light spot 87 by thermomagnetic recording. The reproducing layer 83 is an in-plane magnetized film at room temperature, and has a high temperature region 90 inside the reproducing light spot 87.
Is a magnetic film having a characteristic of being a perpendicular magnetization film only in the portion. When the reproduction laser beam is applied, the temperature rises, and a high-temperature region 90 and a low-temperature region 91 are formed. High temperature area 9
0, the reproducing layer 83 changes to a perpendicular magnetization film and the intermediate layer 84
The magnetization direction of the recording layer 85 is aligned by the magnetic coupling through the. When the temperature decreases due to the movement of the magneto-optical recording medium 80, the reproducing layer 83 changes to an in-plane magnetic film again. Therefore,
The reproducing layer 83 (in-plane magnetic film) in the low-temperature region 91 inside the reproducing light spot 87 acts as a mask, and the recording magnetic domain 89 of the recording layer 85 is transferred only from the high-temperature region 90 of the reproducing light spot 87. For this, the light spot 87
A signal of a recording mark (recording magnetic domain 89) smaller than that can be detected.

As described above, in the magneto-optical recording medium 80, the reproducing light spot 8 is used without using the initialization magnetic field and the reproducing magnetic field.
The information of the recording magnetic domain 89 smaller than 7 can be reproduced.

[0025]

The reproducing layer 8 as described above.
The magneto-optical recording medium 80 using an in-plane magnetized film has the effect of eliminating the need for an initialization magnetic field or a reproducing magnetic field, but has the following disadvantages.

First, even in the masked low-temperature region 91, the magnetization of the reproducing layer 83 is oriented in the direction of the magnetization of the recording layer 85 due to the magnetic interaction between the reproducing layer 83 and the recording layer 85. Attracted. For this reason, an ideal in-plane magnetization direction cannot be maintained and a perpendicular component of magnetization is obtained. As a result, the transfer occurs even in a region where the transfer of the recording magnetic domain 89 is not required, and the resolution becomes insufficient or becomes a noise factor at the time of reproduction.

Second, since the critical temperature at which the reproducing layer 83 changes from an in-plane magnetic film to a perpendicular magnetic film is constant, when the power of the reproducing laser beam (reproducing power) fluctuates, the recording magnetic domain 8
The area where 9 is transferred changes, and the reproduction characteristics deteriorate due to the waveform interference of the transfer magnetic domain.

Further, when the environmental temperature such as the temperature in the drive changes, the setting of the reproducing power needs to be changed. In particular, when the environmental temperature rises, the reproducing power is reduced. The temperature difference between the critical temperature at which signals can be transferred and room temperature is reduced. As a result, the area (low-temperature area 91) masked by the reproducing layer 83, which is an in-plane magnetized film, becomes smaller, so that the reproduction signal is degraded due to a decrease in resolution, and the transfer of the signal of the recording layer 85 is not performed. There is a problem that it becomes insufficient.

In short, the high-temperature region fluctuates according to the fluctuation of the reproduction power and the fluctuation of the environmental temperature.

(II) On the other hand, in the magneto-optical recording medium using the above-described magnetic super-resolution method, a rare earth-transition metal alloy is mainly used for the magnetic layer.

FIG. 14 shows the perpendicular component of the transition metal sublattice magnetic moment at the time of reproduction in a magneto-optical recording medium using a magnetic super-resolution method according to the prior art. Arrow 130 in first magnetic layer 1100 and second magnetic layer 1200
0 and 1400 represent the perpendicular components of the sublattice magnetic moment of the transition metal element of the first magnetic layer 1100 and the second magnetic layer 1200, respectively.

The first magnetic layer 1100 is an in-plane magnetic film at room temperature, but transitions from an in-plane magnetic film to a perpendicular magnetic film as the temperature rises. The second magnetic layer 1200 is made of, for example, Tb.
This film is made of FeCo, DyFeCo, or the like and has a large perpendicular magnetic anisotropy at room temperature. The recorded information is held depending on whether the magnetic domain of the second magnetic layer 1200 is upward or downward with respect to the film surface.

When a light beam is irradiated from the substrate side to the magneto-optical recording medium having such a configuration, a temperature gradient occurs in the beam spot 1700, and a high-temperature region and a low-temperature region exist. At this time, even in the low temperature region in the beam spot 1700, the first magnetic layer 110
0 does not contribute to the polar Kerr effect because it becomes an in-plane magnetized film,
The recorded information held in the second magnetic layer 1200 is masked and becomes invisible.

On the other hand, in a high temperature area in the beam spot 1700, the first magnetic layer 1100 becomes a perpendicular magnetization film,
The information recorded on the second magnetic layer 1200 is transferred to the first magnetic layer 1100 to cause magnetostatic coupling with the second magnetic layer 1200.

Since there is a portion of the entire beam spot 1700 masked by the first magnetic layer 1100, the recording information of the second magnetic layer 1200 is transferred only to an area smaller than the size of the beam spot 1700. Therefore, magnetic super-resolution is realized.

The magneto-optical recording medium using such a magnetic super-resolution method can meet the demand for high density by narrowing the track. A transition region occurs as an intermediate state in which the in-plane magnetization film changes to the perpendicular magnetization film. That is, the entire film does not suddenly transition from the in-plane magnetization film to the perpendicular magnetization film at a predetermined temperature, but has a certain temperature range as the transition region.

In the transition region, the first magnetic layer is no longer a complete in-plane magnetic film, so that the recorded information held by the second magnetic layer cannot be completely masked. Conversely, since the first magnetic layer in this transition region is not a complete perpendicular magnetization film, the magnetostatic coupling force with the second magnetic layer is small, and it is difficult to obtain a large signal.

Therefore, the first magnetic layer in the transition region cannot sufficiently mask the recording information of the second magnetic layer, so that the crosstalk from the adjacent track increases. In addition, the first magnetic layer in the transition region has a weak magnetostatic coupling force with the second magnetic layer, so that the recorded information from the second magnetic layer cannot be sufficiently transferred.

Further, in general, a high-cost rare earth metal is often used as a material for the first magnetic layer. However, when the magnetic layer is a thick film, the material cost increases and the productivity is deteriorated. In addition, it is difficult to provide an inexpensive magneto-optical recording medium.

[0040]

(I) The present invention has been made in view of the problem that the high-temperature region fluctuates in accordance with the fluctuation of the reproduction power and the fluctuation of the environmental temperature. The objectives are as follows: (1) It is possible to simultaneously improve two characteristics, that is, stable magnetic super-resolution mask characteristics and transferability of a recording signal to a reproduction layer even when the environmental temperature changes. To provide a magneto-optical recording medium having high-resolution and high-performance reproduction characteristics, and
(2) To provide a method for reproducing a magneto-optical recording medium suitable for high-density recording using the above-described magneto-optical recording medium.

According to the present invention, there is provided a recording layer having a recording magnetic domain in which information is recorded by a magnetization direction perpendicular to the film surface, and information recorded in the recording layer is magnetically coupled with the magnetization direction perpendicular to the film surface. A reproducing layer transferred and formed as a reproducing magnetic domain, and a transfer control layer magnetically coupled to the recording layer, wherein at least a part of a temperature range lower than a temperature at which the reproducing magnetic domain is transferred to the reproducing layer, The direction of magnetization of the recording layer and the direction of magnetization of the transfer control layer corresponding to the recording layer are opposite to each other, and in at least a part of a temperature range equal to or higher than the transfer temperature, the transfer control layer is not cured. This is a magneto-optical recording medium whose temperature becomes higher than the temperature.

According to the present invention, there is provided a recording layer having a recording magnetic domain in which information is recorded in a magnetization direction perpendicular to the film surface, and information recorded on the recording layer is magnetized perpendicularly to the film surface by magnetic coupling. And a transfer control layer magnetically coupled to the recording layer, and at least a part of a temperature range lower than a temperature at which the read magnetic domain is transferred to the read layer. The direction of magnetization of the recording layer and the direction of magnetization of the transfer control layer corresponding to the recording layer are opposite directions, and at least a part of the temperature range equal to or higher than the transferred temperature, A magneto-optical recording medium in which the direction of magnetization is the same as the direction of magnetization of the transfer control layer corresponding to the recording layer.

Alternatively, in the present invention, in a temperature range lower than the transfer temperature, the direction of magnetization of the recording layer is opposite to the direction of magnetization of the transfer control layer corresponding to the recording layer. It is a magneto-optical recording medium.

Alternatively, according to the present invention, there is provided a method comprising:
Any of the above magneto-optical recording media, wherein the magnetic domain enlarging layer having a shrink function is formed.

In particular, according to this configuration, the magneto-optical recording medium is constituted by a magnetic domain expansion layer having a characteristic of shrinking a reproducing magnetic domain (transfer magnetic domain) or moving a domain wall in a region near a transfer temperature during a reproducing operation. However, transfer of the reproduction signal can be performed smoothly, and reproduction reproduction can be performed by forming a reproduction magnetic domain (transfer magnetic domain) that is larger than the recording magnetic domain of the recording layer.

The Curie temperature of the transfer control layer may be at least lower than the Curie temperature of either the recording layer or the reproducing layer. Thereby, the magnitude of the static magnetic field for transferring the signal of the recording layer to the reproduction layer can be sharply increased.

Alternatively, the Curie temperature of the transfer control layer may be lower than the compensation composition temperature of the reproducing layer. Further, the compensation composition temperature of the transfer control layer may be lower than the compensation composition temperature of the reproduction layer. This makes it possible to stably detect the reproduction magnetic domain transferred to the reproduction layer.

Alternatively, the transfer control layer may be provided farther from the light incident surface than the recording layer.

Alternatively, an intermediate layer made of a non-magnetic material may be further provided between the reproducing layer and the recording layer.

Alternatively, a layer made of a dielectric material may be provided as the intermediate layer made of the nonmagnetic material.
As a result, it is possible to effectively transfer and reproduce the recorded magnetic domains by the static magnetic field from the recording layer to the reproducing layer.

Alternatively, an intermediate layer made of a magnetic material having a Curie temperature lower than both the Curie temperature of the reproducing layer and the Curie temperature of the recording layer is provided between the reproducing layer and the recording layer. You may. Thereby, the mask effect of the reproducing layer or the transfer characteristic of the recording magnetic domain can be improved by utilizing the magnetic exchange coupling force between the recording layer and the reproducing layer.

Alternatively, the recording layer may have a compensation composition temperature between room temperature and the transfer temperature.

Alternatively, a heat absorbing layer made of a metal may be further provided. This makes it possible to control the temperature distribution in the recording film, and obtain a transferred and reproduced signal with higher signal quality.

Also, the present invention provides a recording layer having a recording magnetic domain in which information is recorded by a magnetization direction perpendicular to a film surface, and information recorded in the recording layer being a reproduction magnetic domain by a magnetization direction perpendicular to the film surface. A reproducing layer to be transferred, and a transfer control layer magnetically coupled to the recording layer, and when reproducing the recorded information, in a light spot of reproduced light to be irradiated, magnetization of the recording layer, The magneto-optical recording medium is configured so that there is a region where the magnetization of the transfer control layer corresponding to the recording layer has a critical temperature in which the directions are opposite to each other and the magnitudes match. .

Preferably, in a temperature region not lower than room temperature and not higher than the critical temperature, the magnitude of the added magnetization obtained by adding the magnetization of the recording layer and the magnetization of the transfer control layer is 10
0 emu / cc or less. Accordingly, a reproducing layer which exhibits a mask effect as a magnetic film having magnetic anisotropy in a film plane direction in a reproducing light spot can obtain sufficient mask characteristics.

Also, the present invention provides a recording layer having a recording magnetic domain in which information is recorded in a magnetization direction perpendicular to the film surface, and a recording magnetic domain in which information recorded in the recording layer is formed as a reproducing magnetic domain in a magnetization direction perpendicular to the film surface. A reproducing method for a magneto-optical recording medium comprising at least a reproducing layer to be transferred and a transfer control layer magnetically coupled to the recording layer, wherein when reproducing information recorded on the magneto-optical recording medium, A reproduction light spot is formed by emitting reproduction light to the magneto-optical recording medium, and the directions of the magnetization of the recording layer and the magnetization of the transfer control layer corresponding to the recording layer in the reproduction light spot are mutually opposite. A region having a critical temperature in the opposite direction and having the same size is formed, and a magneto-optical recording medium for reproducing a signal of a transfer magnetic domain formed in the reproducing layer in a temperature region higher than the critical temperature is reproduced. It is a method.

(II) Further, the present invention has been made in view of the problem that the crosstalk from the adjacent track becomes large, and a magneto-optical recording medium aiming at high density by narrowing the track and a reproducing method thereof. Is provided.

To achieve the above object, the present invention provides
A magneto-optical recording medium comprising: a first magnetic layer which becomes an in-plane magnetic film at least at room temperature and becomes a perpendicular magnetic film at a predetermined high temperature higher than the room temperature; and a second magnetic layer having perpendicular magnetic anisotropy. The first magnetic layer has a thickness small enough to transmit a light beam, and the second magnetic layer is disposed so as to be magnetically coupled to the first magnetic layer. When the light beam is incident from the first magnetic layer side, the rotation of the polarization plane of the light beam reflected by the first magnetic layer and the light transmitted through the first magnetic layer and reflected by the second magnetic layer This is a magneto-optical recording medium characterized in that the rotation of the polarization plane of the beam is compensated and canceled out with each other.

Further, according to the present invention, a magneto-optical recording medium is irradiated with a light beam so that information recorded in the second magnetic layer is
A reproducing method for a magneto-optical recording medium for performing reproduction by magnetically coupling the first magnetic layer and the second magnetic layer, wherein the high-temperature region in the beam spot includes the first magnetic layer.
Transferring the information recorded on the second magnetic layer to the first magnetic layer by magnetically coupling the first magnetic layer and the second magnetic layer with the magnetic layer being a perpendicular magnetization film; , In a low temperature region in the beam spot, the first
Rotating the plane of polarization of the light beam reflected by the magnetic layer;
The rotation of the polarization plane of the light beam transmitted through the magnetic layer and reflected by the second magnetic layer compensates for each other and cancels each other,
Reproducing the information.

According to the present invention, in the magneto-optical recording medium using the magnetic super-resolution method, by reducing the thickness of the first magnetic layer, the transition region from the in-plane magnetization film to the perpendicular magnetization film can be formed. Offset the rotation angle of the polarization plane, sufficiently mask the recording information of the second magnetic layer at a temperature from room temperature to the high temperature region in the beam spot, and sufficiently record the information in the high temperature region in the beam spot. Make it reproducible.

[0061]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to specific embodiments. (I) (First Embodiment) First, a first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view schematically showing the structure of a magneto-optical recording medium 100 according to the first embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a polycarbonate optical disk substrate provided with a guide groove for tracking a light spot. On the optical disc substrate 1,
A dielectric layer 2 made of SiN for enhancement is formed, and a GdFeCo reproducing layer 3, a SiN intermediate layer 4, a TbFeCd recording layer 5, and a TbFe transfer control layer 6 are further formed thereon.
Are sequentially laminated to provide a recording film structure having a four-layer structure. Further thereon, a SiN protective layer 7 and an overcoat layer 8 of epoxy acrylate are provided.

Here, the recording film structure composed of the respective layers 3 to 6 has a CAD (Centeraperturedtec) for detecting recording information only from a high-temperature region of a reproduction light spot.
magnetic super-resolution method (hereinafter referred to as CAD)
This method realizes a recording / reproducing method for increasing the recording density using a method having a domain diameter of 0.5 during reproduction.
It has a magnetically-coupled multilayer film structure to increase the amount of read signals in the case of high-density recording and reproduction of μm or less.

The magneto-optical recording medium 100 having the configuration shown in FIG.
In forming the first, a direct current magnetron sputtering apparatus is used to reactively sputter an Si target in a mixed atmosphere of an argon gas and a nitrogen gas to have a pre-groove which is a guide groove for tracking guide of a light spot. An 80 nm SiN film 2 is formed on a polycarbonate substrate 1. Furthermore, GdFeC
After a GdFeCo film 3 was formed in a thickness of 20 nm in an argon gas using a target, a SiN film 4 was formed in a thickness of 15 nm by reactive sputtering, and a TbFeC
o 35 nm for the recording layer 5 and 35 n for the TbFe transfer control layer 6
m, respectively. Further, the SiN protective layer 7 is
m, followed by spin-coating an ultraviolet-curable resin of epoxy acrylate by 6 μm, and then irradiating with ultraviolet light to cure it to form an overcoat layer 8, and the magneto-optical recording medium 100 according to the first embodiment of the present invention. Is obtained.

FIG. 2 shows a magneto-optical recording medium 10 according to this embodiment.
0 shows a configuration at the time of reproduction by the CAD method.
2A is a plan view showing a part of a track of the magneto-optical recording medium 100, and FIG. 2B is a cross-sectional view showing a configuration of a recording film structure of the magneto-optical recording medium 100 (particularly, a direction of magnetization).

The playback principle of the CAD system will be briefly described.

As shown in FIG. 2B, the recording film structure of the magneto-optical recording medium 100 comprises a reproducing layer 3, an intermediate layer 4, a recording layer 5, and a transfer control layer 6. FIG.
9A, reference numeral 9 denotes a reproduction laser beam spot, 12 denotes a mask area, and 10 denotes a reproduction area. The arrow 110 shown in FIG. 2A is a moving direction along the track of the magneto-optical recording medium 100, and each of the layers 3, 5, and 6 in FIG.
The arrows drawn inside indicate the direction of magnetization at each location.

FIGS. 3A to 3C show the magnetic properties of the GdFeCo reproducing layer 3 used in the magneto-optical recording medium 100 of the present invention in a single-layer state by changing the intensity of the reproducing laser beam. 2 shows the results of measuring the car hysteresis loop. Specifically, FIGS. 3 (a), (b) and (c)
In each case, the temperature is around room temperature (the intensity of the reproduction laser beam = 0.
8 mW), 100 ° C. (reproduction laser beam intensity = 1.4 m)
W) and 170 ° C. (intensity of reproduction laser beam = 2.2 m)
It is a measurement result in the case of W).

As shown in FIGS. 3A to 3C, the magnetic anisotropy of the reproducing layer 3 in the direction perpendicular to the film surface increases as the temperature increases. That is, comparing FIGS. 3A to 3C, at a low temperature near room temperature shown in FIG. 3A, the reproducing layer 3 is a magnetic film having magnetic anisotropy in the in-plane direction of the film. As shown in (b) and (c), the magnetic anisotropy in the direction perpendicular to the film surface is induced as the temperature rises with the increase in the reproducing power. In particular, as shown in (c), at a certain temperature or higher, It becomes a perpendicular magnetization film.

As described above, when the reproducing layer 3 becomes a perpendicular magnetization film due to the temperature rise, as shown in FIG.
Due to magnetic interaction from the side of the recording layer 5, the recording layer 5
Can be transferred to the reproducing layer 3 via the intermediate layer 4 and reproduced. The reproducing layer 3 has a large in-plane magnetic anisotropy in the in-plane direction of the film in a range from room temperature to a temperature region 11 lower than the reproducing temperature at which the magnetic domain of the recording layer 5 is transferred. Information recorded as perpendicular magnetization characteristics on the recording layer 5 is not transferred to the reproducing layer 3, and as a result, a mask function is realized.

To reiterate, the magneto-optical recording medium 100
Is rotated in the direction of arrow 110 and the recording layer 5 passes through the reproducing laser beam spot 9, the temperature of the recording layer 5 gradually increases. In a low-temperature region 12 in front of the reproducing laser beam spot 9, the reproducing film 3 functions as a mask while keeping the in-plane magnetic film, but in a high-temperature region 10 at which the reproducing layer 3 becomes a perpendicular magnetic film or higher, recording is performed. A reproduction magnetic domain 13 corresponding to the direction of magnetization of the layer 5 is transferred and formed. Then, after the reproduction laser beam spot 9 has passed, the temperature of the recording film structure decreases again, the recording magnetic domains of the recording layer 6 are not transferred, and the reproduction layer 3 returns to the state of the in-plane magnetic film.

In the magneto-optical recording medium 100 of the present embodiment using such a principle of reproduction, as described with reference to FIGS. 2A and 2B without using a bias magnetic field at the time of reproduction. The temperature region 1 in front of the reproduction laser beam spot 9
1 and the surrounding temperature region 12 function as a mask. Then, transfer and reproduction are performed by the signal of the recording magnetization of the recording layer 5 by the action of the magnetic coupling force with the recording layer 5 at the temperature at which the magnetic anisotropy of the reproducing layer 3 in the direction perpendicular to the film surface increases. be able to.

That is, the information recorded on the recording layer 5 can be read only from the high-temperature area 10.

Therefore, in the magneto-optical recording medium 100 having the structure of the present embodiment, it is possible to reproduce a signal from an area smaller than the reproduction light spot 9, and specifically, to record / reproduce data at a domain length of 0.4 μm. Reproduction becomes possible. Further, in this reproducing method, the reproducing layer 3 is an in-plane magnetized film and functions as a mask (that is, the low-temperature region 1 which is masked).
Since the temperature difference between 1 and 12 and the high-temperature region 10 to which a signal is transferred is used, reproduction is performed with a laser power of 2.5 mW, which is higher than usual.

In the first magnetic layer 101, the temperature region where the transition from the in-plane magnetization film to the perpendicular magnetization film can be set by changing the ratio of each element constituting the first magnetic layer. Generally, when the ratio of rare earth elements is increased,
The temperature region where the transition from the in-plane magnetization film to the perpendicular magnetization film is increased. Conversely, when the temperature region where the in-plane magnetization film transitions to the perpendicular magnetization film is reduced, the ratio of the rare earth element may be reduced.

FIG. 17 shows that the first magnetic layer 1 becomes an in-plane magnetic film at room temperature as described above and becomes a perpendicular magnetic film at high temperature.
FIG. 4 is a diagram showing a relationship between perpendicular magnetic anisotropy energy Ku and demagnetizing field energy 2πMs ² of No. 01 and temperature. In general, when the perpendicular magnetic anisotropy energy is Ku and the saturation magnetization is Ms in the case of the magnetic layer as described above, the following equation is satisfied at room temperature.

[0078]

Ku <2πMs ² where 2πMs ² is the demagnetizing field energy. Ku is 2
If it is smaller than πMs ² , the magnetic layer becomes an in-plane magnetized film.
Assuming that the temperature at which Ku and 2πMs ² coincide with each other is Tm, such a first magnetic layer 101 becomes an in-plane magnetized film in a low-temperature region lower than Tm. As shown in FIG. 17, as the temperature of the magnetic layer increases, the magnitude of Ku and 2πMs ² approaches, and when it exceeds Tm, the following equation is obtained.

[0079]

## EQU2 ## The Ku> 2πMs ² magnetic layer becomes a perpendicular magnetization film when this equation is satisfied.

The first magnetic layer 101 is the second magnetic layer 10
2 is a layer that plays the role of reproducing the information recorded in 2, the larger the Kerr rotation angle is, the better. FIG. 18 is a diagram showing the relationship between the Kerr rotation angle and the Curie temperature. As shown in FIG. 18, the Kerr rotation angle increases as the Curie temperature increases.

Here, the magneto-optical recording medium 10 of the present embodiment
In the recording film structure at 0, the GdFeCo reproducing layer 3 has a rare earth-rich composition at room temperature, a Curie temperature of 300 ° C., and a compensation composition temperature of 270 ° C. Further, since the intermediate layer 4 is a SiN film, an interaction between the intermediate layer 4 and the recording layer 5 is caused by a static magnetic field. The TbFeCo recording layer 5 has a transition metal-rich composition at room temperature, and has a Curie temperature of 280 ° C.
It is. Further, the transfer control layer 6 made of TbFe has a rare-earth-rich composition at room temperature, has a Curie temperature of 160 ° C., and is exchange-coupled to the recording layer 5.

FIG. 4 shows the temperature dependence of the magnetization of the recording layer 5 and the transfer control layer 6. 4, the broken line indicates the temperature dependence of the magnetization of the recording layer 5, and the dotted line indicates the temperature dependence of the magnetization of the transfer control layer 6. Further, the solid line indicates the recording layer 5
It shows the magnitude of the magnetization obtained by adding the two magnetizations obtained when the transfer control layer 6 and the transfer control layer 6 are stacked, that is, the temperature dependence of the magnetic field for transfer (transfer magnetic field).

From this, it is found that the magnitude of the transfer magnetic field, which is the magnitude of the added magnetization of the laminated recording layer 5 and transfer control layer 6, suddenly increases from around 80 ° C.
Therefore, when the recording magnetic domain 13 of the recording layer 5 is transferred to the reproducing layer 3 using the static magnetic field, the magnitude of the static magnetic field changes sharply with respect to the temperature, so that the detection of the reproduction signal is facilitated. .

Actually, the magneto-optical recording medium 10 of the present embodiment
FIG. 5 shows a carrier level characteristic of a reproduction signal with respect to reproduction power at room temperature 25 ° C. of a signal recorded by optical pulse magnetic field modulation recording with a pulse width of 30% of an irradiation laser by applying a recording modulation magnetic field of 300 Oe to 0. Shown in At this time, the NA of the objective lens of the optical head was 0.55, and the laser wavelength of the light source was 680 nm. The rotating velocity of the rotating magneto-optical recording medium is 3.5 m / s, and the recording power is 8 m / s.
Recording was performed by setting the modulation frequency of the recording magnetic field so that the mark length was 0.47 μm at ９9 mW. For comparison, the characteristics (measurement conditions are the same as above) with respect to the reproduction power of the reproduction signal of the magneto-optical recording medium using the conventional magnetic super-resolution without using the transfer control layer 6 of the present invention are also shown. FIG.
It is shown in

In the magneto-optical recording medium having the conventional configuration, the magnitude of the magnetization of the recording layer increases gradually with respect to the temperature, and the transition from the in-plane magnetic film to the perpendicular magnetic film of the reproducing layer also moderates. It is. For this reason, as shown in FIG. 5 as a comparative example (dotted line), even if the reproducing power is 1.0 mW,
A signal of -30 dB or more has been transferred to the maximum value of the carrier level, and the carrier level to be transferred gradually increases as the temperature rises with an increase in the reproduction power. As a result, in the conventional configuration, the critical temperature between the region masked by the reproducing layer and the region to which the magnetic domain of the recording layer is transferred is not clear, and when the environmental temperature changes, the temperature of the in-plane masked region increases. The range is narrowed, or the recording magnetic domain of the recording layer is transferred even with a small laser power. For this reason, in the conventional configuration having no transfer control layer as in the present invention, the magnetic super-resolution operation becomes unstable or the reproduced signal is deteriorated.

On the other hand, the change in the carrier level with respect to the reproducing power of the magneto-optical recording medium 100 of the present embodiment is almost up to the reproducing power of about 1.1 mW.
Is not transferred, and the read power is 1.2 mW.
The carrier level sharply increases from around. This is for the following reason.

In the magneto-optical recording medium 100 of this embodiment,
As shown in FIG. 4, when the reproducing power is small and the temperature of the recording film structure is low, the recording layer 5 and the transfer control layer 6 having different magnetization directions are combined. The recording domain No. 5 is not transferred. However, the recording layer 3
In the high temperature region where the recording magnetic domain is transferred, the transfer control layer 6 has a Curie temperature or higher, so that the transfer is reproduced by the magnetization from only the recording layer 3 side. In particular, near the critical temperature at which a signal is transferred to the reproducing layer 3, a sharp change in magnetization is obtained due to the disappearance of the magnetization of the transfer control layer 6 and the increase in the magnetization of the recording layer 5. Without this, the transfer signal can be detected.

As described above, if the magneto-optical recording medium 100 of the present embodiment is used, even in the case of the magnetic super-resolution using the reproducing layer 3 of the in-plane magnetic film, the reproduction power is transferred by the static magnetic field. It is possible to change the magnetization characteristics sharply,
A magneto-optical recording medium having a large reproduction power margin with respect to a change in environmental temperature can be realized. In addition, a magneto-optical recording medium capable of excellent high-density recording and reproduction, in which deterioration of a reproduction signal due to crosstalk in a magnetic super-resolution mask area is reduced,
And a good information reproducing method can be provided.

Further, the magneto-optical recording medium 100 of the present embodiment
According to the configuration described above, since the transfer control layer 6 has a magnetization characteristic in a direction opposite to that of the recording layer 5, when recording is performed on the recording layer, the influence of the stray magnetic field due to the recording layer 5 around the recording mark is also reduced. Since the magnetic field can be reduced by the magnetization characteristics in the opposite direction, the recording magnetic field characteristics can be improved.

(Second Embodiment) Next, a second embodiment of the present invention will be described.

The magneto-optical recording medium according to the present embodiment has the same configuration as that of the first embodiment shown in FIG. 1. Specifically, on the optical disk substrate 1 made of a plastic material, It has a recording film structure in which a dielectric layer 2 for enhancement is formed, and a reproducing layer 3, an intermediate layer 4, a recording layer 5, and a transfer control layer 6 are sequentially laminated respectively. Further, a protective layer 7 and an overcoat layer 8 are formed thereon. Further, on the transfer control layer 6, A
You may add a heat control absorption layer with large thermal conductivity, such as 1 and Cu.

Here, the recording film structure composed of the respective layers 3 to 6 realizes a recording / reproducing method for increasing the recording density using the CAD system, similarly to the first embodiment, and has a domain diameter at the time of reproduction. It has a magnetically coupled multilayer structure to increase the amount of read signals in the case of high-density recording and reproduction of 0.5 μm or less. In the present embodiment, the intermediate layer 4
In the case where a magnetic film of GdDyFe is used, an in-plane mask is formed in a low temperature region by exchange coupling between the reproducing layer 3 and the intermediate layer 4 and the intermediate layer 4 has a high temperature higher than the Curie temperature. Only the recorded magnetic domains 13 of the recording layer 5 are transferred and reproduced. Since the characteristics of the reproduction layer 3 and the operation principle at the time of reproduction are almost the same as those of the first embodiment, detailed description is omitted here.

Referring to FIG. 1, the magneto-optical recording medium according to the present embodiment will be described. An optical disk substrate 1 made of polyolefin having meandering prepits for tracking a light spot is used. 80 nm thick ZnS as a dielectric layer 2 for
The film is formed by RF sputtering. The recording film structure thereon has a GdFeCo reproducing layer 3, 25 nm of 30 nm.
GdDyFe intermediate layer 4, 50 nm TbFeCo
Cr recording layer 5, 35 nm DyFeCo transfer control layer 6
Are sequentially formed by DC sputtering. Furthermore, a ZnS.SiO ₂ protective layer 7 is further
A film is formed to a thickness of 10 nm by F sputtering.
An AlTi heat absorbing layer having a thickness of 40 nm is formed by DC sputtering. And, on top of that, an epoxy-based UV curable resin is applied by spin coating and cured,
An overcoat layer 8 is formed.

Here, in the recording film of this embodiment, G
The dFeCo reproducing layer 3 has a rare-earth-rich composition at room temperature, and has a Curie temperature of 310 ° C. and a compensation composition temperature of 280 ° C. The GdDyFe intermediate layer 4 has a transition metal rich composition having magnetic anisotropy in the in-plane direction of the film, and has a Curie temperature of 140 ° C. Further, the TbFeCoCr recording layer 5 provided with the intermediate layer 4 interposed therebetween has a transition metal-rich composition at room temperature, and has a Curie temperature of 270 ° C. The transfer control layer 6 made of DyFeCo has a rare-earth-rich composition at room temperature, a Curie temperature of 200 ° C., and a compensation composition temperature of 110 ° C., and has a configuration in which it is exchange-coupled to the recording layer 5.

FIG. 6 shows the temperature dependence of the magnetization of the recording layer 5 and the transfer control layer 6 as described above. 4, the broken line indicates the temperature dependence of the magnetization of the recording layer 5, and the dotted line indicates the temperature dependence of the magnetization of the transfer control layer 6. Further, the solid line indicates the recording layer 5
It shows the magnitude of the magnetization obtained by adding the two magnetizations obtained when the transfer control layer 6 and the transfer control layer 6 are stacked, that is, the temperature dependence of the magnetic field for transfer (transfer magnetic field).

As shown, the magnetization of the recording layer and the magnetization of the transfer control layer are equal to the compensation composition temperature of the transfer control layer 6.
Up to around 0 ° C., the directions of magnetization are opposite to each other, so that the two layers cancel each other. However, when the temperature is equal to or higher than the compensation composition temperature, the transfer control layer 6 also has a transition metal-rich composition, and its magnetization direction matches the magnetization direction of the recording layer 5. 5, the transfer magnetic field sharply increases.

At this time, if the intermediate layer 4 is kept at the Curie temperature or higher, magnetic extinction occurs and stable transfer becomes possible.

The intermediate layer 4 is an in-plane magnetic film at a temperature lower than the Curie temperature and assists the in-plane magnetization component of the magnetization of the reproducing layer 3, so that the mask characteristics are also improved. As a result, short marks (recorded magnetic domains) are obtained. In this case, the detection of the reproduced signal is facilitated.

As a result, the carrier level changes with respect to the reproducing power of the magneto-optical recording medium in this embodiment, as in the case of the first embodiment, the signal of the recording magnetic domain of the recording layer 5 is almost unchanged up to the reproducing power of 1.2 mW. No transfer is performed, and the carrier level sharply increases from around 1.4 mW of reproduction power.

Further, in the present embodiment, the transfer magnetic field at a low temperature can be reduced by the configuration using the transfer control layer 6, and the directions of the magnetization of the recording layer 5 and the transfer control layer 6 are opposite. However, in a temperature range of 80 ° C. or less, which is a temperature at which the sizes match (also referred to as a critical temperature), the magnitude of the added magnetization (transfer magnetic field) of the laminated recording layer 5 and transfer control layer 6 Is less than 100 emu / cc (see FIG. 6). Therefore, near the critical temperature, the transfer magnetic field is almost canceled.

Further, in this embodiment, although the integrated magnetization (transfer magnetic field) is relatively increased near the room temperature and in the opposite direction, in the temperature range around room temperature, the in-plane of the reproducing layer Since the magnetic anisotropy becomes larger and there are sufficient mask characteristics, the reverse characteristic of the integrated magnetization does not matter.

Therefore, according to the configuration of the present embodiment, in the low temperature region, the recording magnetic domains of the recording layer 5 are not transferred, so that the in-plane mask characteristics of the reproducing layer 3 are improved, while the recording magnetic domains of the recording layer 3 are transferred. In a high temperature region, the transfer control layer 6 has a temperature equal to or higher than the compensation composition temperature, so that stable transfer is performed by magnetization from the recording layer 3 side and reproduction is performed. As a result, in the magneto-optical recording medium of the present embodiment, recording / reproduction with a domain length of 0.4 μm becomes possible.

As described above, in the present embodiment, the information signal of 0.5 μm or less can be stably recorded / reproduced by the configuration in which the recording layer and the transfer control layer are laminated in the CAD system using magnetic super-resolution. And an excellent magneto-optical recording medium can be realized.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to the drawings.

FIG. 7 is a sectional view schematically showing the configuration of the magneto-optical recording medium 300 according to the present embodiment.

In FIG. 7, a dielectric layer 22 for enhancement made of SiN is formed on a polycarbonate optical disk substrate 21 having a guide groove for tracking a light spot, and a GdFeC layer is further formed thereon.
o Magnetic domain expansion layer 23, GdFeCoCr reproduction layer 24, Al
N intermediate layer 25, TbFeCo recording layer 26, DyTbFe
A recording film structure having a five-layer structure in which Co transfer control layers 27 are sequentially stacked is provided. On such a recording film structure, an AlCrN heat control layer 28, an AlCr heat absorption layer 29,
An overcoat layer 30 of an epoxy-based ultraviolet curable resin is provided.

As a method of forming the magneto-optical recording medium 300 of this embodiment, first, a Si target is reactively sputtered by a DC magnetron sputtering apparatus in a mixed atmosphere of argon gas and nitrogen gas to form a light spot. An 80 nm-thick SiN film 22 is formed on a polycarbonate substrate 21 having a configuration capable of performing recording on a land portion and a groove portion for tracking guide. Further, after forming a GdFeCo film 23 to a thickness of 20 nm by sputtering in an argon gas using a GdFeCo target, sputtering is performed in an argon gas using a GdFeCoCr tergate to form a GdFeCoCr film 24 having a thickness of 15 nm. Formed. Further, an AlN film 25 is formed to a thickness of 25 nm by DC sputtering of an Al target in a mixed atmosphere of an argon gas and a nitrogen gas. On top of that, Tb
Using the respective targets of FeCo and DyTbFeCo, the TbFeCo recording layer 26 is
The FeCo transfer control layer 27 is laminated to a thickness of 30 nm. Further, using an AlCr target, an AlCrN heat control layer 28 was formed to a thickness of 20 nm by reactive sputtering in a mixed atmosphere of argon gas and nitrogen gas.
The heat absorption layer 29 is formed to a thickness of 50 nm by C sputtering. Then, an ultraviolet-curable epoxy resin is applied thereon by spin coating to a thickness of 6 μm, and then cured by irradiating ultraviolet rays to form an overcoat layer 30. Thus, the magneto-optical recording medium 300 of the present embodiment is obtained.

Here, the recording film structure of the magneto-optical recording medium 300 of the present embodiment composed of the layers 23 to 27 has a multi-layer film structure utilizing magnetic domain expansion using the shrink type magnetic domain expansion layer 23, thereby reducing the recording density. It can realize a method of increasing the size, and has a multilayer structure magnetically coupled in order to increase the amount of read signals in the case of high-density recording / reproduction with a domain diameter of 0.4 μm or less during reproduction.

FIG. 8 is a diagram showing a configuration at the time of reproduction of the magneto-optical recording medium 300 using the shrink type magnetic domain enlarging layer 23 which is one type of the magnetic domain enlarging system of the present embodiment. FIG. 3B is a plan view showing a part of a track of the magneto-optical recording medium 300, and FIG. Note that an arrow 310 shown in FIG. 8A is a moving direction along a track of the magneto-optical recording medium 300.
Arrows drawn in each of the layers 23, 24, 26 and 27 in (b) indicate the direction of magnetization at each location.

With reference to FIG. 8, a brief description will be given of the reproduction principle of this embodiment.

As shown in FIG. 8B, the recording film structure of the magneto-optical recording medium 300 according to the present embodiment includes a magnetic domain expansion layer 23, a reproducing layer 24, an intermediate layer 25, a recording layer 26, and a transfer control layer 27. It has a five-layer structure. In FIG. 8A, reference numeral 35 denotes a reproduction laser beam spot, reference numerals 31 and 32 denote mask regions (specifically, 31 denotes a low-temperature region and 32 denotes a high-temperature region), and 33 denotes a reproducible temperature region. The recording magnetic domains 34 are recorded on the recording layer 26. here,
The recording layer 26 and the transfer control layer 27 have magnetizations in opposite directions at room temperature, the reproducible temperature region 33 is higher than the Curie temperature of the transfer control layer 27, and the Curie temperature of the recording layer 26 is , The temperature must be higher than the temperature of the reproducible temperature region 33.

In the recording film structure of the magneto-optical recording medium 300 of the present embodiment, the GdFeCo magnetic domain expansion layer 23 has a rare-earth-rich composition at room temperature, and has a Curie temperature of 310.
° C and the compensating composition temperature is 100 ° C. Also, the reproduction layer 24
Is the transition metal rich composition of the in-plane magnetic film at room temperature,
It is formed from GdFeCoCr having a Curie temperature of 190 ° C. Further, the AlN intermediate layer 25 is a layer that blocks exchange coupling, and the TbFeCo recording layer 26 laminated via the intermediate layer 25 has a rare-earth metal-rich composition at room temperature, a Curie temperature of 300 ° C., and a compensation composition temperature. 110 ° C. The transfer control layer 27 made of DyTbFeCo has a transition metal-rich composition at room temperature, and has a Curie temperature of 140 ° C.
In this configuration, the recording layer 26 is exchange-coupled.

Here, FIGS. 10 (a) to 10 (c) show the magnetic characteristics (Kerr hysteresis loop) at different temperatures when the magnetic domain expansion layer 23 in the magneto-optical recording medium 300 of this embodiment is provided as a single layer. And directions of magnetization). Specifically, FIG. 10A shows 50 ° C., and FIG.
10 ° C., (c) is a graph at 160 ° C.

Taking the Kerr hysteresis loop of FIG. 10A as an example, when a magnetic field H is applied to the magnetic domain expansion layer 23 from the plus side to the minus side, a magnetic field of about -180 Oe is obtained.
The magnetization state of A in FIG. Further, when the magnetic field H is applied from the magnetization state of B to the magnetic domain enlarging layer 23 toward the plus side, the magnetic domain enlarging layer 23 reappears around the magnetic field enlarging layer A at about -70 Oe, which is a magnetic field on the negative side of 0. Invert to state. As described above, the Kerr hysteresis loop of the magnetic domain enlarging layer 23 included in the magneto-optical recording medium 300 of the present embodiment causes the applied magnetic field to shift in the negative direction as shown in FIGS. In particular, when the temperature shown in FIG. 10A or 10B is low, the direction of magnetization is uniform in one direction in the absence of an external magnetic field. Is masked by

The function of the reproducing layer 24 is the same as in the first and second embodiments.

Therefore, in the low-temperature region 31 within the reproducing light spot 35, the reproducing layer 24 has magnetic anisotropy in the in-plane direction of the film.
And is masked by the shrink operation of the magnetic domain expansion layer 23 described above.

The high-temperature area 32 of the reproduction light spot 35
In this case, since the reproducing layer 24 has a Curie temperature or higher, the recording magnetic domains 34 of the recording layer 26 are slightly transferred to the magnetic domain enlarging layer 23.

For this reason, the recording magnetic domain 34 is transferred to the magnetic domain enlarging layer 23 via the reproducing layer 24 only from the intermediate temperature region 33 in the reproducing light spot 35. At this time, since the reproducing layer 24 has a Curie temperature or higher, the magnetic domain expanding layer 23
In this case, the domain wall is likely to move in the direction of the high-temperature area 32, and an area 344 larger than the recording magnetic domain 34 is transferred and formed on the magnetic domain expansion layer 23.

That is, the portion S of the magnetic domain expansion layer 23 formed on the portion of the reproduction layer 24 where the magnetization is annihilated (hatched portion) is at an intermediate temperature of the reproduction layer 24 due to the influence of the recording layer 26. Since the influence from the portion P of the magnetic domain expansion layer 23 formed on the perpendicularly magnetized portion is greater, the magnetic domain expands toward that portion.

As a result, the transfer signal of the recording magnetic domain 34 is reproduced as the reproducing magnetic domain 344 enlarged by the domain wall movement. In addition, in the shrink type reproduction method of the present embodiment, in order to satisfy the above-described reproduction operation, 2.
Reproduction is performed with a laser power of 5 mW.

The magneto-optical recording medium 3 of this embodiment as described above
FIG. 9 shows the temperature dependence of the magnetizations of the recording layer 26 and the transfer control layer 27 included in 00. 9, the broken line indicates the temperature dependence of the magnetization of the recording layer 26, and the dotted line indicates the transfer control layer 2.
7 shows the temperature dependence of the magnetization of No. 7. Further, the solid line indicates the recording layer 2
6 shows the magnitude of the magnetization obtained by adding the magnetizations obtained when the transfer control layer 6 and the transfer control layer 27 are stacked, that is, the temperature dependence of the magnetic field for transfer (transfer magnetic field).

In the recording film structure of the present embodiment, TbFeC
The o recording layer 26 has a rare earth metal-rich composition at room temperature, and has a Curie temperature of 300 ° C and a compensation composition temperature of 110 ° C. The transfer control layer 27 made of DyTbFeCo
Has a transition metal rich composition at room temperature and a Curie temperature of 14
The temperature is 0 ° C. and the recording layer 26 is exchange-coupled. Looking at the magnitude of the added magnetization (transfer magnetic field) of the laminated recording layer 26 and transfer control layer 27, in the temperature range of 100 ° C. or less, the magnetization directions of the recording layer and the transfer control layer are different. Since the directions are opposite to each other, the magnetizations of the two cancel each other. However, when the temperature exceeds about 100 ° C., the magnetizations of the two coincide with each other.
Rapidly increases. Accordingly, when the magnetic layer is transferred to the magnetic domain enlarging layer 23 by using the magnetic coupling via the intermediate layer 25, the magnitude of the magnetic interaction in the state where the reproducing layer 24, the recording layer 26, and the transfer control layer 27 are stacked. Changes sharply with respect to the temperature, and the formation of the reproducing magnetic domain 34 by the transfer in the intermediate temperature region 33 in the reproducing light spot 35 becomes easy. Then, in the magnetic domain expansion layer 23, the recording magnetic domain by transfer is formed in an enlarged state (reference numeral 34 in FIG. 8).
4).

In practice, the magneto-optical recording medium 30 of the present embodiment
0, a recording magnetic field of 300 Oe is applied and a pulse width of 4
The carrier level of the reproduction signal with respect to the reproduction power of the signal having the mark length of 0.27 μm recorded by the optical pulse magnetic field modulation recording of 0% is 1.0 m as in the first embodiment.
The carrier level sharply increases at a reproduction power of W or more. Moreover, in the magneto-optical recording medium 300 of the present embodiment,
As shown in the characteristic diagram of the signal amplitude of the reproduction signal with respect to the mark length (the size of the recording magnetic domain) in FIG. 11, the decrease in the signal amplitude is small even when the mark length is reduced.

Here, FIG. 11 shows the relative signal amplitude (relative signal) normalized by the amplitude when the mark length is 3 μm.
It is the figure plotted with respect to mark length. Thus, in the configuration of the present embodiment, even if the mark length is 0.3 μm or less, an amplitude of 50% or more of the amplitude level at the mark length of 3 μm can be obtained. Therefore, according to the present embodiment, the short recording domain 3
4, it is confirmed that the recording magnetic domain 34 is reproduced while being formed as the magnetic domain 344 enlarged at the time of transfer. FIG. 11 also shows, for comparison, data in the magneto-optical recording medium according to the related art and the magneto-optical recording medium according to the first embodiment of the present invention.

As described above, by using the magneto-optical recording medium 300 of this embodiment, the shrink type magnetic domain enlarging layer 2 can be used.
3, the transfer characteristics can be sharply changed with respect to the reproduction power, and a magneto-optical recording medium having a large reproduction power margin with respect to a change in environmental temperature can be realized.

Further, it is possible to reduce the crosstalk due to the enlargement of the transfer magnetic domain and the mask characteristic, and the mark length is 0.3 μm.
It is possible to provide a magneto-optical recording medium capable of excellent recording and reproduction even in the case of high-density recording of m or less, and a good information reproducing method.

In the recording / reproducing method of the magneto-optical recording medium according to each embodiment of the present invention, the optical magnetic recording medium of the present invention described above can be reproduced with a higher reproducing power than usual. A signal (recorded information) is detected using a magnetic recording / reproducing device.

In such a recording / reproducing apparatus for a magneto-optical recording medium, recording, reproducing, and erasing of information are performed by using a laser beam. However, at the time of reproducing a signal, a part of a reproducing laser beam spot irradiated on the magneto-optical recording medium is irradiated. In the region, the magnitude of the magnetization of the recording layer matches the magnitude of the magnetization of the transfer control layer in the opposite direction (the temperature becomes such a temperature, that is, the critical temperature). In such a region having a temperature higher than the critical temperature where the magnitudes of the magnetizations match, the recording magnetic domain of the recording layer is transferred to the reproducing layer having the property of transitioning from the in-plane direction to the magnetic film in the vertical direction. Is done. Thus, it is possible to reproduce a signal from an area smaller than the reproduction light spot. As a result, an excellent magneto-optical recording medium in which the transfer area can be easily controlled, and the transition from the low-temperature mask area to the high-temperature transfer area is steep, so that a reproduction margin for a change in environmental temperature can be increased. The recording / reproducing apparatus and the reproducing method described above are realized.

Further, according to another aspect of the present invention, in a reproduction temperature range near a temperature at which the saturation magnetization obtained by adding the magnetization of the stacked recording layer and the magnetization of the transfer control layer is maximized,
By transferring the magnetic domain recorded on the recording layer to the reproducing layer, the magnetic coupling force between the recording layer and the intermediate layer and the reproducing layer via the reproducing auxiliary layer is larger than the domain wall contraction force of the reproducing layer. , And reproduces signals (recorded information). At this time, at least a part of the light spot of the magneto-optical recording medium heated by the laser beam irradiated at the time of signal reproduction has the magnetization direction of the recording layer and the magnetization direction of the transfer control layer opposite to each other. However, the temperature raising process is performed so as to reach a critical temperature which is a temperature at which the sizes match. by this,
A signal recorded only from a temperature range in which a signal can be transferred by a magnetic coupling force between a recording layer and a reproduction layer in a region other than the vicinity of the critical temperature range as described above within the reproduction light spot. Is transferred and detected as a reproduction signal. Alternatively, in a part of the reproduction light spot, a region other than the vicinity of the critical temperature range where the magnitude of the magnetization of the recording layer and the magnitude of the reverse magnetization of the transfer control layer coincide with each other, When the recorded signal is transferred only from a temperature range in which the signal can be transferred by the magnetic coupling force during the transfer, the transferred magnetic domain is enlarged (that is, by using the enlarged transferred magnetic domain), and the signal is enlarged. May be detected.

(II) Next, another embodiment of the present invention will be described with reference to the drawings.

(Embodiment 4) FIG. 15 is a sectional view of a magneto-optical recording medium according to Embodiment 4 of the present invention. Substrate 1
08 is a substrate made of polycarbonate. Polycarbonate substrates are often used as substrates for magneto-optical recording media because of their ease of molding. The substrate 108 has a land / groove configuration, and has a track width of 0.6 μm.

The magneto-optical recording medium according to the present embodiment is
08, the first dielectric layer 109 / the first magnetic layer 101 /
In this configuration, the second dielectric layer 110 / second magnetic layer 102 / third dielectric layer 111 / overcoat layer 112 are formed.

Next, a method of manufacturing the magneto-optical recording medium shown in FIG. 15 will be described.

For forming a thin film on the substrate 108, a sputtering apparatus was used. TbFe for sputtering equipment
Co alloy target, GdFeCo alloy target, S
The i target is installed on each independent cathode, and a substrate 108 made of polycarbonate is installed on a substrate holder in a sputtering apparatus. After installing the substrate 108, the inside of the chamber of the sputtering apparatus is set to 2 × 10 ^−7.
Evacuation was performed with a cryopump until a high vacuum of Torr or less was obtained.

After evacuating to a high vacuum, Ar gas was introduced into the chamber at 2 × 10 ⁻³ Torr and N 2 gas was introduced at 4 × 10 ⁻³ Ton.
rr was introduced, an input power of 1 kW was applied, and a SiN film as the first dielectric layer 109 was formed on the substrate 108 by DC sputtering. In the present embodiment, the thickness of the SiN film as the first dielectric layer 109 is set to 80 n.
m.

Next, the degree of vacuum in the chamber is again set to 2 ×
At 10 ^-7 Torr or less, Ar gas is introduced into the chamber at 5 × 10 ^-3 Torr. After introducing Ar gas, GdFeC, which is the first magnetic layer 101, is formed on the first dielectric layer 109.
An o film was formed. The sputtering method is a DC sputtering method as in the case of the first dielectric layer 109.

The thickness of the first magnetic layer 101 is made thin so that a light beam can be transmitted. In the present embodiment, the thickness of the GdFeCo film as the first magnetic layer 101 is set to 20 nm.

In the present embodiment, the first magnetic layer 101
The composition of the GdFeCo film is Gd30.6Fe61.
1Co8.3 (at.%). First of this embodiment
The magnetic layer 101 is a rare earth-rich composition GdFeCo film that transitions from an in-plane magnetization film to a perpendicular magnetization film in a temperature region where the Curie temperature is around 320 ° C. and around 150 ° C.

After forming the first magnetic layer 101, the 2 × 1
After evacuation to 0 ⁻⁷ Torr, the second dielectric layer 110 was formed on the first magnetic layer 101. Second dielectric layer 1
Reference numeral 10 uses an SiN film similarly to the first dielectric layer 109, and the film forming conditions are the same as those of the first dielectric layer 109, and Ar gas is introduced into the chamber at 2 × 10 ⁻³ Torr and N 2 gas. Was introduced at 4 × 10 ⁻³ Torr, and an input power of 1 kW was applied to form a film.

The thickness of the second dielectric layer 110 strongly affects the magnetostatic coupling between the first magnetic layer 101 and the second magnetic layer 102. The smaller the thickness of the second dielectric layer 110 is,
The distance between the magnetic layer 101 and the second magnetic layer 102 becomes shorter,
Since the magnetostatic coupling force is increased, the thickness of the second dielectric layer 110 is desirably 100 nm or less, and more desirably 30 nm or less. However, the second dielectric layer 110
When the film thickness of the second dielectric layer 110 is very thin, the exchange coupling force between the first magnetic layer 101 and the second magnetic layer 102 becomes larger than the magnetostatic coupling force, so that the film thickness of the second dielectric layer 110 becomes 2 nm or more. It is necessary to. In the present embodiment, the thickness of the second dielectric layer 110 is set to 10 nm. The upper limit of the thickness of the second dielectric layer is desirably 100 nm or less. If the thickness is more than 100 nm, the magnetostatic coupling force between the first magnetic layer and the second magnetic layer becomes small.

Next, after evacuating again to 2 × 10 ⁻⁷ Torr, Ar gas was introduced into the chamber at 5 × 10 ⁻³ Torr.
rr was introduced, and a TbFeCo film as the second magnetic layer 102 was formed on the second dielectric layer 110 to a thickness of 50 nm.

In this embodiment, the composition of the TbFeCo film is Tb22.1Fe71.2Co6.7 (at.
%). T, which is the second magnetic layer 102 of the present embodiment,
The bFeCo film is transition metal rich with a Curie temperature of 240 ° C.

Next, vacuum evacuation is performed again to 2 × 10 ⁻⁷ Torr. After evacuation, Ar gas is introduced into the chamber at 2 × 10 ⁻³ Torr and N as in the first dielectric layer 109.
Two gases were introduced at 4 × 10 ⁻³ Torr. After the introduction, a power of 1 kW is applied to the second magnetic layer 102 similarly to the first dielectric layer 109 and the second dielectric layer 110, and the
A SiN film as the dielectric layer 111 was formed.

The thickness of the third dielectric layer 111 needs to protect the second magnetic layer 102 from corrosion such as oxidation.
50 nm or more is desirable. In the present embodiment, the thickness of the third dielectric layer 111 is set to 80 nm.

The magneto-optical recording medium having the respective thin films formed on the substrate 108 under the above conditions is taken out of the chamber, and an ultraviolet curable resin is applied on the film surface side of the magneto-optical recording medium by spin coating, and the ultraviolet light is irradiated. The overcoat layer 112 was produced by irradiation. In the present embodiment, the thickness of the overcoat layer 112 is set to 10 μm by controlling the viscosity of the ultraviolet curable resin and the rotation speed of the spin coater.

The reproducing layer t of this embodiment has the same or similar characteristics as the reproducing layer used in the first embodiment.

The first magnetic layer 10 of the magneto-optical recording medium of the present invention
For No. 1, a rare earth-transition metal alloy having a composition in which the sublattice magnetic moment of the rare earth element is dominant was used. First magnetic layer 10
1 has magnetic characteristics as shown in FIGS. 3A, 3B and 3C depending on the temperature.

FIG. 16A is a diagram showing the relationship between the Kerr rotation angle and the external magnetic field at room temperature. First magnetic layer 101
Is an in-plane magnetized film at room temperature, the magnetization is hardly oriented in the vertical direction with a small external magnetic field in the vertical direction, and a very large external magnetic field is required to direct the magnetization in the vertical direction.

FIG. 16B is a diagram showing the relationship between the Kerr rotation angle and the external magnetic field at a temperature at which the magnetization transitions from the in-plane direction to the vertical direction. In this temperature region, when a certain external magnetic field is applied, all the magnetizations in the film are oriented in the perpendicular direction, but the Kerr rotation angle is small because the film acts as an in-plane magnetic film for a small external magnetic field.

FIG. 16C is a diagram showing the relationship between the Kerr rotation angle and the external magnetic field at a high temperature. At high temperatures, the film becomes a perpendicular magnetization film, saturates even with a small external magnetic field, and provides a large Kerr rotation angle. The first magnetic layer 101 has a structure shown in FIG.
(B) As shown in (c), a film which becomes an in-plane magnetic film at room temperature and becomes a perpendicular magnetic film as the temperature becomes higher is used.

As described above, the first magnetic layer 101 is suitably made of a material and a composition that increase the Curie temperature. In the present embodiment, the first magnetic layer 101 of GdFe
The Co film has a Curie temperature of 320 ° C.

FIG. 19 is a diagram showing the relationship between the saturation magnetization Ms of the second magnetic layer 102 used in this embodiment and the temperature.
The magnetostatic coupling force has a strong correlation with the magnetic moment, and the larger the magnetic moment, the greater the magnetostatic coupling force. Since the magnetic moment is proportional to the product of the saturation magnetization and the film thickness, the saturation magnetization has a great effect on the magnetostatic coupling force. The second magnetic layer 102 used in this embodiment is made of Tb22.1
Transition metal-rich TbFeCo having a composition of Fe71.2Co6.7 (at.%) And a Curie temperature of 240 ° C.
It is a membrane.

In the second magnetic layer 102, when the compensation temperature is near room temperature, the difference between the saturation magnetization at room temperature and the saturation magnetization at the transfer temperature increases, and the change in saturation magnetization with temperature becomes sharper. Further, since the perpendicular magnetic anisotropy is large and the coercive force is large at room temperature, it is possible to stably hold recorded information. The saturation magnetization of the second magnetic layer 102 used in the present embodiment at room temperature is almost 0, and as the temperature rises, the saturation magnetization of the second magnetic layer 102 increases to a predetermined temperature, that is, the first magnetization. Magnetic layer 101
When the recording information is transferred to the second magnetic layer 10
2 shows a saturation magnetization value at which a signal can be sufficiently transferred from the information recorded in No. 2 to the first magnetic layer 101.

The thickness of the second magnetic layer 102 is the same as that of the first magnetic layer 1.
In order to transfer a signal to the first magnetic layer 01, the magnetic moment of the second magnetic layer 102 needs to be increased. Further, if the thickness of the second magnetic layer 102 is too large, the power of the light beam required for increasing the temperature increases, which causes a decrease in recording sensitivity. Therefore, the thickness of the second magnetic layer 102 is 200 nm or less. It is desirable that In the present embodiment, the second magnetic layer 1
02 was set to 50 nm.

Next, the recording / reproducing characteristics of the magneto-optical recording medium manufactured in the present embodiment were examined.

In the reproducing method of the present invention, a semiconductor laser having a wavelength of 650 nm and an objective lens having an NA of 0.6 were used. The linear velocity of the medium was 3.5 m / s.

For recording signals on the magneto-optical recording medium, an optical pulse magnetic field modulation system was used. Recording power of 9 mW, dut
irradiating the magneto-optical recording medium with a light beam as y50%;
The temperature of the second magnetic layer 102 is raised to the Curie temperature or higher.
A signal was recorded by bringing the magnetic head close to the surface opposite to the light beam and modulating the direction of the magnetic flux generated from the magnetic head by the recording magnetic field of 350 Oe.

The reproduction of the information recorded on the second magnetic layer 102 is performed by first irradiating a light beam to the magneto-optical recording medium to thereby reproduce the first magnetic layer 1 in the beam spot 107.
In addition to raising the temperature of 01 to create the region of the perpendicular magnetization film,
By raising the temperature of the second magnetic layer 102, the beam spot 10
7, the magnetic moment of the second magnetic layer 102 is increased.

Next, the first magnetic layer 101 and the second magnetic layer 10
The signal of the second magnetic layer 102 is transferred to the first magnetic layer 101 by the magnetostatic coupling of No. 2.

Finally, a signal is detected from the light beam reflected by the magneto-optical recording medium by the magneto-optical effect.

FIG. 20 is a diagram showing the relationship between the signal amount and the reproduction power in the magneto-optical recording medium according to the present embodiment.
FIG. 21 is a diagram showing the relationship between the amount of crosstalk and the reproduction power in the magneto-optical recording medium according to the present embodiment. The signal amount is a signal size of 1.88 μm, and the crosstalk amount is a signal amount of 1.88 μm recorded on one adjacent track 106 and the signal amount leaking from the adjacent track 106 in the reproduction track 105. , Playback track 10
5 shows the ratio to the signal amount when a 1.88 μm signal was reproduced.

When the reproducing power is small, most of the area in the beam spot 107 is a low-temperature area, and the first magnetic layer 101 is an in-plane magnetization film. Since the rotation of the plane is not large and is canceled by the rotation of the polarization plane of the light beam transmitted through the first magnetic layer 101 and reflected by the second magnetic layer 102, only a small signal is detected as shown in FIG. It is not possible.

When the reproducing power is slightly increased, the first magnetic layer 101 near the center of the beam spot 107 transits slightly from the in-plane magnetic film to the perpendicular magnetic film. First magnetic layer 10
A signal can be detected from a region where 1 has transitioned to a perpendicular magnetization film. However, the first within the beam spot 107
Since the portion where the magnetic layer 101 transitions to the perpendicular magnetization film is a narrow region, the signal amount is very small. In an area away from the center in the beam spot 107, the first magnetic layer 1
Since 01 is a temperature region where the transition from the in-plane magnetic film to the perpendicular magnetic film occurs, the rotation of the polarization plane of the light beam reflected by the first magnetic layer 101 and the transmission through the first magnetic layer 101 and the second magnetic layer The rotation of the polarization plane of the light beam reflected at 102 is canceled.

When the reproducing power is further increased, the temperature becomes high in a wide area from the center of the beam spot 107, and the first magnetic layer 101 changes from an in-plane magnetic film to a perpendicular magnetic film. In a wide area within the beam spot 107, the first
The magnetic layer 101 has transitioned to a perpendicular magnetization film.

Here, in the high-temperature region in the beam spot 107, the rotation of the polarization plane of the light beam reflected by the first magnetic layer 101 is small because the first magnetic layer 101 is a perpendicular magnetization film. The first magnetic layer 101 in the temperature range during the transition from the in-plane magnetization film to the perpendicular magnetization film
It becomes larger than the rotation of the plane of polarization of the light beam reflected by the magnetic layer 101. First magnetic layer 10 in beam spot 107
The rotation of the plane of polarization of the light beam reflected by the first magnetic layer 1
Since the rotation of the polarization plane of the light beam reflected by the first magnetic layer 101 becomes larger than the rotation of the polarization plane of the light beam reflected by the first magnetic layer 101, a large signal can be detected.

As the reproducing power increases, the high-temperature area in the beam spot 107 expands, so that the first magnetic layer 101 transitions from the in-plane magnetization film to the perpendicular magnetization film in a wide area within the beam spot 107. As a result, a large signal can be obtained.

Further, as shown in the characteristic diagram of the amount of crosstalk leaking from the adjacent track 106 with respect to the reproducing power in FIG. 21, when the reproducing power is small, that is, when the temperature in the beam spot 107 is near room temperature, ,
Since the amount of signal is small, the amount of crosstalk is relatively large, and the amount of crosstalk further increases as the reproduction power increases. However, the range of a certain reproduction power (1.2 to 2.0 mW in FIG.
It can be seen that the crosstalk from the adjacent track 106 is reduced in the range (1).

In the reproduction power region where the signal amount is large and the crosstalk amount is small as shown in FIGS. 20 and 21, the first magnetic layer 1 near the center in the beam spot 107 is formed.
Reference numeral 01 denotes a perpendicular magnetization film, and the first magnetic layer 101 in a region away from the center in the beam spot 107 is a temperature region in the process of transition from the in-plane magnetization film to the perpendicular magnetization film.

As shown in FIG. 14, the beam spot 10
In a region away from the center in 7, the vertical component 103 of the sublattice magnetic moment of the transition metal element in the first magnetic layer is smaller than that in the center region. For this reason, the light beam reflected by the first magnetic layer 101 and the light beam transmitted through the first magnetic layer 101 and reflected by the second magnetic layer 102 are almost equal in magnitude with the rotation direction of the polarization plane reversed. Become. Since the adjacent track 106 is a relatively low temperature area away from the center in the beam spot 107, the first track
The light beam reflected by the magnetic layer 101 and the light beam transmitted through the first magnetic layer 101 and reflected by the second magnetic layer 102 are substantially equal in magnitude with opposite rotation directions of the polarization plane. Therefore, crosstalk from the adjacent track 106 is greatly reduced.

Conversely, near the center of the beam spot 107,
That is, in the reproduction track 105, it is a high temperature area,
Since the magnetic layer 101 transitions from the in-plane magnetization film to the perpendicular magnetization film, a large signal can be obtained.

The saturation magnetization of the second magnetic layer 102 at this time will be described. FIG. 6 shows the relationship between the saturation magnetization of the second magnetic layer 102 and the temperature. The saturation magnetization at room temperature is very small. When the temperature is raised from room temperature by irradiating a light beam, the saturation magnetization increases up to a certain temperature.

When a light beam is irradiated with a reproducing power capable of obtaining a large signal amount, the beam spot 107
The saturation magnetization near the center of the inside becomes maximum. Since the temperature is lower in the region away from the center in the beam spot 107 than in the vicinity of the center, the saturation magnetization is smaller than the saturation magnetization near the center in the beam spot 107.

As shown in FIGS. 20 and 21, a large signal amount is obtained in a wide reproduction power range, and the crosstalk amount is -20 dB or less. Since the crosstalk amount is a signal amount from the adjacent track 106,
This is a region away from the center of the beam spot 107, and is a low-temperature region within the beam spot 107. At this time, the signal amount due to the crosstalk amount is beam spot 1
Since the signal amount is less than one tenth of the signal amount in the high-temperature region in 07, it does not cause deterioration of the reproduced signal.

Next, the reproducing method of the magneto-optical recording medium used in this embodiment will be described in detail. A light beam is irradiated from the substrate 108 side of the magneto-optical recording medium. In this embodiment, the wavelength of the light beam is 650 nm, and the numerical aperture NA of the objective lens is 0.6.

FIG. 14 shows the sub-lattices of the transition metal elements of the first magnetic layer 101, the second magnetic layer 102, and the first magnetic layer when irradiated with a light beam at a reproduction power capable of sufficiently obtaining a signal amount. The vertical component 103 of the magnetic moment and the vertical component 104 of the sublattice magnetic moment of the transition metal element of the second magnetic layer are shown. In the present embodiment, the first magnetic layer 101 is configured to be thin enough to transmit light,
A part of the light beam emitted from the eight sides is
1 and reaches the second magnetic layer 102.

As shown in FIG. 14, in the configuration of the present embodiment, in a region away from the center in the beam spot 107, the first magnetic layer 101 is in the process of transition from an in-plane magnetic film to a perpendicular magnetic film. Therefore, the perpendicular component 103 of the sublattice magnetic moment of the transition metal element of the first magnetic layer is smaller than that of the central region. The light beam depends on the configuration of the optical pickup, but the beam spot 107 is about 1.0 μm.
When the track width is reduced in order to detect a signal from the range, a part of the signal from the second magnetic layer 102 through the first magnetic layer 101 in the adjacent track 106 is detected, and the reproduced signal is degraded. It is thought that.

However, in the present embodiment, the first magnetic layer 1
The light beam reflected at 01 and the light beam transmitted through the first magnetic layer 101 and reflected at the second magnetic layer 102 are substantially equal in magnitude with opposite rotation directions of the polarization plane. Adjacent track 1
Numeral 06 is a relatively low temperature region distant from the center of the beam spot 107, so that the light beam reflected by the first magnetic layer 101 and the light beam transmitted through the first magnetic layer 101 and reflected by the second magnetic layer 102 are reflected. The light beam and the rotation direction of the polarization plane are opposite and the magnitudes are substantially equal. Therefore, the adjacent track 1
Crosstalk from 06 is greatly reduced.

Conversely, near the center of the beam spot 107,
That is, since the reproduction track 105 is in a high temperature region, the first magnetic layer 101 changes from an in-plane magnetic film to a perpendicular magnetic film.

For this reason, the rotation of the polarization plane of the light beam reflected by the first magnetic layer 101 becomes larger than the rotation of the polarization plane of the light beam reflected by the second magnetic layer 102, and The rotation of the plane of polarization of the reflected light beam becomes dominant. Then, the first magnetic layer 101 and the second magnetic layer 102
The light beam reflected by the detector is detected by a detector, converted into an electric signal, and reproduced through a signal processing system.

(Embodiment 5) Next, a fifth embodiment will be described. FIG. 22 is a sectional view of the magneto-optical recording medium according to the present embodiment. In the present embodiment, a magneto-optical recording medium in which the thickness of the GdFeCo film corresponding to the first magnetic layer 101 of the fourth embodiment is 30 nm was manufactured. That is, the first dielectric layer 109 / first
Magnetic layer 101 / second dielectric layer 110 / second magnetic layer 102
/ The third dielectric layer 111 / the heat dissipation layer 113 / the overcoat layer 112, and the first magnetic layer 101 of GdFeC
The thickness of the o film is 30 nm, and the heat dissipation layer 113 is provided between the SiN film as the third dielectric layer 111 and the overcoat layer 112.
Is provided. The substrate 108 has a track width of 0.6
This is a μm polycarbonate substrate.

The formation of the AlTi film as the heat radiation layer 113 is as follows.
An AlTi alloy target was set on one of the cathodes of the sputtering apparatus used in this embodiment, and the inside of the chamber was evacuated to 2 × 10 ⁻⁷ Torr or less. After evacuation, Ar gas was introduced into the chamber at 1.5 × 10 ⁻³ T.
orr is introduced. After introducing Ar gas, the input power is 600W
The AlTi film was formed by applying the DC sputtering method. Other films are formed by using the same sputtering apparatus as that of the magneto-optical recording medium of the fourth embodiment.
The film was formed by DC sputtering under the same film forming conditions as for the magneto-optical recording medium.

In this embodiment, recording and reproduction of signals on and from the magneto-optical recording medium are performed in the same manner as in the fourth embodiment. FIG. 23 is a diagram showing the relationship between the signal amount and the reproducing power in the magneto-optical recording medium according to the present embodiment, and FIG. 24 is a diagram showing the relationship between the crosstalk amount and the reproducing power in the magneto-optical recording medium according to the present embodiment. is there.

In this embodiment, the adjacent track 1
In the case of No. 06, the light beam reflected by the first magnetic layer 101 and the light beam transmitted through the first magnetic layer 101 and reflected by the second magnetic layer 102 cancel each other out in the direction of rotation of the plane of polarization. The effect of reducing the amount of crosstalk in the vicinity of the reproducing power similar to that described above was obtained.

(Embodiment 6) Next, a sixth embodiment will be described. In the present embodiment, as in Embodiment 5, as shown in FIG. 22, a first dielectric layer 109 / first magnetic layer 101 / second dielectric layer 110 / second magnetic layer 102 are sequentially formed on a substrate 108. / Third dielectric layer 111 / heat dissipation layer 113 /
While forming the overcoat layer 112, the thickness of the GdFeCo film as the first magnetic layer 101 was set to 40 nm,
The configuration is such that the thickness of the SiN film as the second dielectric layer 110 is 5 nm.

In the present embodiment, the SiN film as the third dielectric layer 111 and the overcoat layer 1 are formed in the same manner as in the fifth embodiment.
12, a heat radiation layer 113 was provided with a thickness of 35 nm. The substrate 108 is a substrate for a sample servo system having a track width of 0.6 μm, and is made of polycarbonate. The film forming method and the film forming conditions are the same as those of the fifth embodiment by using the same sputtering apparatus as the magneto-optical recording medium of the fifth embodiment.
The film was formed by DC sputtering under the same film forming conditions as for the magneto-optical recording medium.

In the present embodiment, recording and reproduction of signals on and from the magneto-optical recording medium were performed in the same manner as in the fourth embodiment. FIG. 25 is a diagram showing the relationship between the signal amount and the reproducing power in the magneto-optical recording medium according to the present embodiment, and FIG. 26 is a diagram showing the relationship between the crosstalk amount and the reproducing power in the magneto-optical recording medium according to the present embodiment. .

Also in this embodiment, the adjacent track 1
06, the light beam reflected from the first magnetic layer 101 and the first
Since the light beam transmitted through the magnetic layer 101 and reflected from the second magnetic layer 102 cancels out the rotation direction of the polarization plane in the opposite direction, the amount of crosstalk near the reproduction power similar to the fourth and fifth embodiments is obtained. Was obtained.

(Seventh Embodiment) Next, a seventh embodiment will be described. This embodiment is similar to the fifth embodiment.
As shown in FIG. 22, a first dielectric layer 109 / first magnetic layer 101 / second dielectric layer 110 / second dielectric layer
A magneto-optical recording medium having a configuration in which the magnetic layer 102 / the third dielectric layer 111 / the heat radiation layer 113 / the overcoat layer 112 was formed and in which the composition of the GdFeCo film as the first magnetic layer 101 was changed was manufactured.

In the present embodiment, the composition of the first magnetic layer 101 is Gd25.0Fe66.7Co8.3 (at.%).
And the film thickness was 30 nm. Also, the second dielectric layer 110
The thickness of the SiN film was 10 nm. Embodiment 5
Similarly, a heat radiation layer 113 having a thickness of 35 nm was provided between the SiN film as the third dielectric layer 111 and the overcoat layer 112. The substrate 108 is a polycarbonate substrate having a track width of 0.8 μm. The film forming method and the film forming conditions are the same as those of the magneto-optical recording medium of the fifth embodiment, using the same sputtering apparatus as the magneto-optical recording medium of the fifth embodiment, and the film forming conditions by the DC sputtering method. Was done.

The composition of the first magnetic layer 101 was changed to Gd25.0F.
Comparing the case of e66.7Co8.3 (at.%) with the case of the composition of the fifth embodiment, in this embodiment, the temperature region where the transition from the in-plane magnetization film to the perpendicular magnetization film is lower. Was. However, by setting the reproducing power low, the magnetic super-resolution operation can be performed, and the recording and reproducing at a high density can be realized even with the composition of the present embodiment.

In the present embodiment, recording and reproduction of signals on and from the magneto-optical recording medium were performed in the same manner as in the fourth embodiment.

The composition of the first magnetic layer 101 was changed to Gd25.0F.
Also in the present embodiment with e66.7Co8.3 (at.%), the first magnetic layer 101
The light beam reflected by the first magnetic layer 101 and the second
Since the light beam reflected by the magnetic layer 102 negates the direction of rotation of the polarization plane in the opposite direction, the amount of crosstalk becomes −20 dB or less in a wide range of reproduction power, and particularly the reproduction power is 1.2 mW to 2.2 mW. , The crosstalk amount became −25 dB or less, and the same effect as in the fifth embodiment was obtained.

(Embodiment 8) This embodiment has the same film configuration as that of Embodiment 7 and the composition of the first magnetic layer 101 is Gd.
35.4Fe56.3Co8.3 (at.%) And a magneto-optical recording medium produced by increasing the ratio of rare earth metal, contrary to the seventh embodiment. The first dielectric layer 109 / first magnetic layer 101 / second dielectric layer 110 / second magnetic layer 102 / third dielectric layer 111 / heat radiation layer 113 /
This is a configuration in which the overcoat layer 112 is formed. The thickness of the first magnetic layer 101 was 30 nm. As in the seventh embodiment, the thickness of the SiN film as the second dielectric layer 110 is set to 10
nm. As in the fifth and seventh embodiments, a heat dissipation layer 113 having a thickness of 35 nm was provided between the SiN film as the third dielectric layer 111 and the overcoat layer 112. The substrate 108 is a polycarbonate substrate having a track width of 0.7 μm. The film forming method and the film forming conditions are the same as those of the magneto-optical recording medium of the fifth embodiment, using the same sputtering apparatus as the magneto-optical recording medium of the fifth embodiment, and the film forming conditions by the DC sputtering method. Was done.

The composition of the first magnetic layer 101 was changed to Gd35.4F
Comparing the case of e56.3Co8.3 (at.%) with the case of the composition of the fifth embodiment, in this embodiment, the temperature region where the transition from the in-plane magnetization film to the perpendicular magnetization film is increased. Was. However, by setting the reproducing power high, the magnetic super-resolution operation becomes possible, and high-density recording / reproducing can be realized even with the composition of the present embodiment. In this case, increasing the Curie temperature of the second magnetic layer 102 is more effective.

In this embodiment, recording and reproduction of signals on and from the magneto-optical recording medium are performed in the same manner as in the fourth embodiment.

The composition of the first magnetic layer 101 was changed to Gd35.4F
Also in the present embodiment with e56.3Co8.3 (at.%), the first magnetic layer 101
The light beam reflected by the first magnetic layer 101 and the second
Since the rotation direction of the plane of polarization of the light beam reflected by the magnetic layer 102 cancels out in the opposite direction, the crosstalk amount becomes −20 dB or less in a wide range of reproduction power, and especially the reproduction power is 2.0 mW to 3.0 mW. , The crosstalk amount became −25 dB or less, and the same effect as in the fifth embodiment was obtained.

In the description of each of the above embodiments, a magneto-optical recording medium having a structure in which a spiral or annular guide groove for tracking a light spot or a meandering pit is used, using a polycarbonate or polyolefin disk substrate. However, a meandering spiral guide groove having address information or a pre-pit for tracking guide such as a sample servo method may be provided on the disk substrate.

Note that, in the embodiment of the present invention, 0.6 μm
A substrate having a track width of m to 0.8 μm was used.
The same effect can be obtained with a substrate having the following track width.

The thickness of the first magnetic layer 101 is determined by the light reflected by the first magnetic layer 101 and the second magnetic layer transmitted by the first magnetic layer 101 in the adjacent track 106 due to the transmission of the light beam. Since the light reflected by the magnetic layer 102 cancels out the rotation angle of the polarization plane in the opposite direction, as shown in FIG.
In consideration of the relationship between the thickness of the first magnetic layer 101 and the normalized output, the thickness is desirably 40 nm or less, and when the thickness is 30 nm or less, the effect is more enhanced. However, if it is less than 5 nm, a sufficient reproduced signal cannot be obtained, so that it is preferably 5 nm or more, and more preferably 8 nm or more.

In the embodiment of the present invention, the first magnetic layer 101 is made of GdFeCo which has a composition of an in-plane magnetization film at room temperature and a perpendicular magnetization film at high temperature.
Even if the composition is other than the above-described embodiment, the same effect can be obtained as long as it has the property of forming an in-plane magnetic film at room temperature and a perpendicular magnetic film at high temperature.

The first magnetic layer 101 has GdFeC
rare earth-transition metal alloys other than o, such as GdTbFeC
The same effect can be obtained with o, GdDyFeCo, DyFeCo, etc. as long as the film becomes an in-plane magnetic film at room temperature and a perpendicular magnetic film at high temperature.

[0202] Even if Cr or Al is added to the rare earth-transition metal alloy serving as the first magnetic layer 101, the same characteristics can be obtained as an in-plane magnetization film at room temperature and a perpendicular magnetization film at high temperature. The effect is obtained.

In the embodiment of the present invention, Tb22.1Fe71.2Co6.7 is formed on the second magnetic layer 102.
(TbFeCo) having a composition of (at.%) Was used. However, as long as the film has a large coercive force at room temperature, is a perpendicular magnetization film, and can retain recorded information, the same effect can be obtained even with a composition other than the above. Is obtained.

As described above, according to the structure of the embodiment of the present invention, the thickness of the first magnetic layer can be reduced to 40 nm or less, so that the material cost can be reduced and the film forming time can be reduced. Can be shortened, so that the productivity can be greatly improved.

Further, as a recording film structure, TbFeCo,
Although a magneto-optical recording medium having a configuration in which a plurality of magnetic films such as TbFe and GdFeCo are laminated has been described,
Co, GdCo, GdTbFe, GdTbFeCo, D
amorphous alloy of rare earth-transition metal such as yFeCo, or magneto-optical material using MnBi, PtMnSn, polycrystalline material, or platinum group-transition metal alloy such as garnet, PtCo, PdCo, Pt / Co, Pd Gold or a platinum group-transition metal periodic structure alloy film such as / Co or the like, or a recording film structure including these and having a plurality of magnetic films of different materials or compositions may be used. In addition, Cr, Al, Ti, P
Elements for improving corrosion resistance, such as t and Nb, may be added.

Further, the recording layer laminated on the reproducing layer and the intermediate layer, and the transfer control layer, have a thickness of 30 nm to 50 n.
Although a configuration having a recording layer having a thickness of m and a transfer control layer having a thickness of 30 to 35 nm has been described, the present invention is not limited to the above thickness, and the recording is performed so as to satisfy the characteristics of the present invention. What is necessary is just a film thickness configuration that can provide a sufficient magnetic coupling force between the layer and the reproducing layer. More preferably, both the recording layer and the transfer control layer have a thickness of 10 nm to 200 n.
Within the range of m, the same effect can be obtained.

[0207] Also, the configuration in which the transfer control layer is disposed farther from the recording layer when viewed from the light input surface side has been described.
If the configuration is such that the transfer magnetic field to the reproduction layer changes steeply, the configuration may be such that the recording layer is disposed farther than the transfer control layer when viewed from the light input surface side.

Further, by using a recording film structure having a multilayer structure, C
The magneto-optical recording medium and its reproducing method using the magnetic super-resolution reproducing of the AD method, or the reproducing method of expanding the reproducing magnetic domain by the shrink operation have been described, but other FAD method, RAD method, or the like. Using a recording / reproducing method that achieves high signal quality and high recording density, such as a magnetic super-resolution method other than the above, a magnetic domain expansion reproducing method of a domain wall displacement type, or a reproducing magnetic field alternating type reproducing method, If a configuration having a transfer control layer at the time of reproduction transfer is used, the same or better effects can be obtained.

Also, with respect to a magneto-optical recording medium having a recording film configuration using magnetostatic coupling in the light modulation direct overwrite method, if the configuration of the present invention is used, an excellent magneto-optical recording medium having a steep transfer characteristic can be obtained. And its recording / reproducing method.

In the third embodiment of the present invention, a configuration using a reproducing layer has been described. However, a configuration in which a recording auxiliary layer and the like are further added may be used.

When a non-magnetic blocking layer is used as the intermediate layer, it may be a dielectric film or a non-magnetic alloy film. Further, in the case of the above-mentioned non-magnetic alloy film, the characteristics can be further improved if the configuration further uses a reflection layer of a non-magnetic alloy containing at least Al, Cu, Ag, and Au. Further, an intermediate layer including a reflective layer and a dielectric layer may be provided.

In the embodiment of the present invention, the first
Although SiN was used for the dielectric layer 109, the second dielectric layer 110, and the third dielectric layer 111, AlN, SiAlN
Nitrides such as films, oxides such as SiO and AlO, ZnS, Z
The same effect can be obtained by using a dielectric layer such as a chalcogen compound such as nTe or a non-magnetic material other than the dielectric layer.

In the case where a magnetic film is used as the intermediate layer,
An intermediate layer having smaller domain wall energy than these layers may be provided between the recording layer and the reproducing layer (or the magnetic domain expansion layer).

Further, the configuration in which the heat absorption layer made of metal is provided on the transfer control layer via the dielectric layer has been described.
A configuration in which a heat absorbing layer made of a metal is disposed directly on the transfer control layer or the recording layer may be used.

Further, a configuration in which a reflective layer made of a metal is further provided may be employed.

Also, instead of the heat radiation layer, AlTi, AlC
Similar effects can be obtained by using a metal layer of r, Cu, Au, Ag, or the like, or a film having at least one of these and having high thermal conductivity.

Further, since thinning is possible, heat diffusion and heat absorption can be improved, and the temperature distribution inside the magnetic layer in the region irradiated with the beam spot can be sharpened. The resolution is improved in the magnetic super-resolution method.

[0218]

As described above, when the magneto-optical recording medium and the reproducing method of the present invention are used, even when the magnetic super-resolution using the in-plane magnetized film is used, the change in the environmental temperature is not affected. It is possible to realize a magneto-optical recording medium with a large reproduction power margin and excellent transfer characteristics, and reduce deterioration of the reproduction signal due to crosstalk in the magnetic super-resolution mask area. It is possible to provide a simple magneto-optical recording medium and a good information reproducing method.

Further, according to the present invention, by reducing the thickness of the first magnetic layer, the first magnetic layer in the transition region from the in-plane magnetization film to the perpendicular magnetization film in the beam spot at the time of reproduction is reproduced.
The light beam reflected by the magnetic layer and the light beam reflected by the second magnetic layer cancel each other out, sufficiently masking the recorded information of the second magnetic layer at a temperature ranging from room temperature to a high temperature range, and In the area, it is possible to narrow the track by making the recorded information sufficiently reproducible,
A remarkable effect of increasing the recording density can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically illustrating a configuration of a magneto-optical recording medium according to a first embodiment of the present invention.

FIGS. 2A and 2B are diagrams for explaining a reproducing operation of the magneto-optical recording medium according to the first embodiment of the present invention, wherein FIG. 2A is a plan view showing a part of a track, and FIG. FIG. 3 is a cross-sectional view showing a structure (in particular, a direction of magnetization).

FIGS. 3 (a) to 3 (c) show the GdFeCo reproducing layer used in the magneto-optical recording medium of the first embodiment of the present invention at different temperatures realized by changing the intensity of the reproducing laser beam. It is a figure showing the result of having measured the Kerr hysteresis loop which is a magnetic property in a single layer state.

FIG. 4 is a diagram showing the temperature dependence of the magnetization of the recording layer, the magnetization of the transfer control layer, and the transfer magnetic field in the magneto-optical recording medium according to the first embodiment of the present invention.

FIG. 5 is a diagram showing the dependence of the carrier level of the reproduction signal on the reproduction power in the magneto-optical recording medium according to the first embodiment of the present invention.

FIG. 6 is a diagram showing the temperature dependence of the magnetization of the recording layer, the magnetization of the transfer control layer, and the transfer magnetic field in the magneto-optical recording medium according to the second embodiment of the present invention.

FIG. 7 is a cross-sectional view schematically illustrating a configuration of a magneto-optical recording medium according to a third embodiment of the present invention.

8A and 8B are diagrams for explaining a reproducing operation of a magneto-optical recording medium according to a third embodiment of the present invention, where FIG. 8A is a plan view showing a part of a track, and FIG. FIG. 3 is a cross-sectional view showing a structure (in particular, a direction of magnetization).

FIG. 9 is a diagram illustrating the temperature dependence of the magnetization of the recording layer, the magnetization of the transfer control layer, and the transfer magnetic field in the magneto-optical recording medium according to the third embodiment of the present invention.

FIGS. 10A to 10C show magnetic properties (Ker hysteresis) of GdFeCo magnetic domain expansion layers used in the magneto-optical recording medium according to the third embodiment of the present invention at different temperatures in a single-layer state. FIG. 3 is a diagram illustrating a loop and a direction of magnetization.

FIG. 11 is a diagram showing the dependence of the signal amplitude of a reproduction signal on the mark length in the magneto-optical recording medium according to the third embodiment of the present invention.

12A and 12B are diagrams illustrating a reproducing operation of a conventional double-mask type magneto-optical recording medium, wherein FIG. 12A is a plan view showing a part of a track, and FIG. FIG. 2 is a cross-sectional view showing the direction of magnetization in particular.

13A and 13B are diagrams illustrating a reproducing operation of another conventional magneto-optical recording medium of a CAD system, in which FIG. 13A is a plan view showing a part of a track, and FIG. FIG. 2 is a cross-sectional view showing the direction of magnetization in particular.

FIG. 14 is a diagram showing a perpendicular component of a transition metal sublattice magnetic moment during reproduction in the magneto-optical recording medium according to the embodiment of the present invention.

FIG. 15 is a sectional view showing a magneto-optical recording medium according to a fourth embodiment of the present invention.

16A is a diagram showing the relationship between the Kerr rotation angle and the external magnetic field at room temperature of the first magnetic layer of the magneto-optical recording medium of the present invention. FIG. 16B is a diagram showing the surface of the first magnetic layer of the magneto-optical recording medium of the present invention. FIG. 7C is a diagram showing the relationship between the Kerr rotation angle and the external magnetic field at the temperature at which the inner magnetization film transitions to the perpendicular magnetization film. (C) The relationship between the Kerr rotation angle and the external magnetic field at high temperature of the first magnetic layer of the magneto-optical recording medium of the present invention. Diagram shown

FIG. 17 shows perpendicular magnetic anisotropy energy Ku and demagnetizing field energy 2π of the first magnetic layer of the magneto-optical recording medium of the present invention.
Diagram showing the relationship between Ms ² and temperature

FIG. 18 is a diagram showing the relationship between the Kerr rotation angle and the Curie temperature of the first magnetic layer of the magneto-optical recording medium of the present invention.

FIG. 19 is a diagram showing the relationship between the saturation magnetization Ms of the second magnetic layer of the magneto-optical recording medium of the present invention and temperature.

FIG. 20 is a diagram showing a relationship between a signal amount and a reproduction power in a magneto-optical recording medium according to a fourth embodiment of the present invention.

FIG. 21 is a diagram showing a relationship between a crosstalk amount and a reproducing power in a magneto-optical recording medium according to a fourth embodiment of the present invention.

FIG. 22 is a sectional view showing a magneto-optical recording medium according to the fifth to eighth embodiments.

FIG. 23 is a diagram showing a relationship between a signal amount and a reproduction power in a magneto-optical recording medium according to a fifth embodiment of the present invention.

FIG. 24 is a diagram showing a relationship between a crosstalk amount and a reproducing power in a magneto-optical recording medium according to a fifth embodiment of the present invention.

FIG. 25 is a diagram showing a relationship between a signal amount and a reproduction power in a magneto-optical recording medium according to a sixth embodiment of the present invention.

FIG. 26 is a diagram showing a relationship between a crosstalk amount and a reproducing power in a magneto-optical recording medium according to a sixth embodiment of the present invention.

FIG. 27 is a diagram showing a perpendicular component of a transition metal sublattice magnetic moment during reproduction in a magneto-optical recording medium according to a conventional technique.

FIG. 28 is a diagram showing the relationship between the thickness of the magnetic layer and the normalized output in the magneto-optical recording medium according to the eighth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Substrate 2 Dielectric layer 3 Reproducing layer 4 Intermediate layer 5 Recording layer 6 Transfer control layer 7 Protective layer 8 Overcoat layer 9 Reproducing light spot 10 High temperature area 11, 12 Low temperature area 13 Recording magnetic domain 21 Substrate 22 Dielectric layer 23 Magnetic domain expansion Layer 24 Reproducing layer 25 Intermediate layer 26 Recording layer 27 Transfer control layer 28 Dielectric layer 29 Heat absorbing layer 30 Overcoat layer 31 Low temperature area 32 High temperature area 33 Intermediate temperature area 34 Recording magnetic domain 344 Expanded recording magnetic domain 35 Reproducing light spot 101 First magnetic layer 102 Second magnetic layer 103 Perpendicular component of sublattice magnetic moment of transition metal element of first magnetic layer 104 Perpendicular component of sublattice magnetic moment of transition metal element of second magnetic layer 105 Reproduced track 106 Adjacent track 107 Beam spot 108 Substrate 109 First dielectric layer 110 Second dielectric layer 111 Third dielectric layer 112 Overcoat layer 113 Heat dissipation layer

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 11/105 511 G11B 11/105 511C 511G 511Q 531 531V 586 586L 586M (72) Inventor Yasumori Hino Kadoma Osaka Prefecture 1006 Kadoma, Ichidai-shi Matsushita Electric Industrial Co., Ltd. F term (reference) 5D075 CC11 EE03 FF12 FG02

Claims (27)

[Claims] 1. A recording layer having a recording magnetic domain in which information is recorded by a magnetization direction perpendicular to a film surface, and a reproduction magnetic domain in a direction of magnetization perpendicular to the film surface by magnetic coupling of information recorded in the recording layer. And a transfer control layer magnetically coupled to the recording layer. In at least a part of a temperature range lower than a temperature at which the reproduction magnetic domain is transferred to the reproduction layer, the recording layer is formed. And the direction of magnetization of the transfer control layer corresponding to the recording layer is the opposite direction. In at least a part of the temperature range equal to or higher than the transfer temperature, the transfer control layer is equal to or higher than the Curie temperature. Magneto-optical recording medium. 2. A recording layer having a recording magnetic domain in which information is recorded in a magnetization direction perpendicular to a film surface, and a reproducing magnetic domain in a direction of magnetization perpendicular to the film surface by magnetic coupling of information recorded in the recording layer. And a transfer control layer magnetically coupled to the recording layer. In at least a part of a temperature range lower than a temperature at which the reproduction magnetic domain is transferred to the reproduction layer, the recording layer is formed. And the direction of magnetization of the transfer control layer corresponding to the recording layer is the opposite direction, and at least part of the temperature range equal to or higher than the transfer temperature, the direction of magnetization of the recording layer A magneto-optical recording medium in which the direction of magnetization of the transfer control layer corresponding to the recording layer matches. 3. In a temperature range lower than the transfer temperature, the direction of magnetization of the recording layer is opposite to the direction of magnetization of the transfer control layer corresponding to the recording layer. The magneto-optical recording medium according to the above. 4. A magnetic domain expanding layer having a shrink function is formed on the reproducing layer.
A magneto-optical recording medium according to claim 1. 5. The magneto-optical recording medium according to claim 1, wherein the Curie temperature of the transfer control layer is lower than at least one of the recording layer and the reproducing layer. 6. The magneto-optical recording medium according to claim 1, wherein the Curie temperature of the transfer control layer is lower than the compensation composition temperature of the reproducing layer. 7. The magneto-optical recording medium according to claim 1, wherein a compensation composition temperature of the transfer control layer is lower than a compensation composition temperature of the reproduction layer. 8. The magneto-optical recording medium according to claim 1, wherein the transfer control layer is provided farther from the light incident surface than the recording layer. 9. The image forming apparatus according to claim 1, further comprising an intermediate layer made of a non-magnetic material between the reproducing layer and the recording layer.
5. The magneto-optical recording medium according to any one of items 1 to 4. 10. A layer made of a dielectric material is provided as the intermediate layer made of a nonmagnetic material.
3. The magneto-optical recording medium according to claim 1. 11. An intermediate layer made of a magnetic material and having a Curie temperature lower than both the Curie temperature of the reproducing layer and the Curie temperature of the recording layer is provided between the reproducing layer and the recording layer. The magneto-optical recording medium according to claim 1, wherein 12. The magneto-optical recording medium according to claim 1, wherein the recording layer has a compensation composition temperature between room temperature and a transfer temperature. 13. The magneto-optical recording medium according to claim 1, further comprising a heat absorbing layer made of a metal. 14. A recording layer having a recording magnetic domain in which information is recorded in a magnetization direction perpendicular to a film surface, and reproduction in which information recorded in the recording layer is transferred as a reproduction magnetic domain in a magnetization direction perpendicular to the film surface. And a transfer control layer magnetically coupled to the recording layer. When reproducing the recorded information, in the light spot of the reproduction light applied, the magnetization of the recording layer and the recording layer A magneto-optical recording medium configured so that there is a region where the magnetization of the corresponding transfer control layer has a critical temperature in which the directions are opposite to each other and the magnitudes are the same. 15. In a temperature range from room temperature to the critical temperature, the magnitude of the added magnetization obtained by adding the magnetization of the recording layer and the magnetization of the transfer control layer is 100 emu.
The magneto-optical recording medium according to claim 14, which is not more than / cc. 16. A recording layer having a recording magnetic domain in which information is recorded in a magnetization direction perpendicular to a film surface, and reproduction in which information recorded in the recording layer is transferred as a reproduction magnetic domain in a magnetization direction perpendicular to the film surface. Layer, a reproduction method for a magneto-optical recording medium comprising at least a transfer control layer magnetically coupled to the recording layer, when reproducing information recorded on the magneto-optical recording medium,
A reproduction light is emitted to the magneto-optical recording medium to form a reproduction light spot. In the reproduction light spot, the directions of the magnetization of the recording layer and the magnetization of the transfer control layer corresponding to the recording layer are mutually opposite. A region having a critical temperature in a direction opposite to that of the critical temperature, and reproducing a signal of a transfer magnetic domain formed in the reproducing layer in a temperature region higher than the critical temperature. Method. 17. An in-plane magnetized film at least at room temperature,
Further, in a magneto-optical recording medium including a first magnetic layer which becomes a perpendicular magnetization film at a predetermined high temperature higher than the room temperature, and a second magnetic layer having perpendicular magnetic anisotropy, the first magnetic layer comprises The second magnetic layer is arranged so as to be magnetically coupled to the first magnetic layer, and the light beam for reproduction is transmitted through the first magnetic layer. When incident from the side, the rotation of the polarization plane of the light beam reflected by the first magnetic layer and the rotation of the polarization plane of the light beam transmitted through the first magnetic layer and reflected by the second magnetic layer are mutually different. A magneto-optical recording medium characterized in that compensation and cancellation are performed. 18. A recording track is formed on the second magnetic layer, and a light beam reflected by the first magnetic layer in a predetermined region on the first magnetic layer adjacent to the track. 18. The rotation according to claim 17, wherein the rotation of the polarization plane and the rotation of the polarization plane of the light beam transmitted through the first magnetic layer and reflected by the second magnetic layer are compensated for each other and cancel each other. Magneto-optical recording medium. 19. The magneto-optical recording medium according to claim 18, wherein the predetermined area is a temperature area where the first magnetic layer transitions from an in-plane magnetic film to a perpendicular magnetic film. 20. A rotation of a polarization plane of the light beam reflected by the first magnetic layer in a low-temperature region lower than the predetermined high temperature in a beam spot formed by the light beam during reproduction, and 2. The structure according to claim 1, wherein the rotation of the polarization plane of the light beam transmitted through the first magnetic layer and reflected by the second magnetic layer is compensated for each other and canceled.
8. The magneto-optical recording medium according to 7. 21. At a temperature not higher than the temperature at which the saturation magnetization of the second magnetic layer is maximized, rotation of the plane of polarization of the light beam reflected by the first magnetic layer and transmission of the second magnetic layer through the first magnetic layer. 2. The structure according to claim 1, wherein the rotation of the polarization plane of the light beam reflected by the magnetic layer is compensated for and canceled out.
8. The magneto-optical recording medium according to 7. 22. The first magnetic layer has a rare earth-transition metal alloy and is a magnetic layer in which a sub-lattice magnetic moment of a rare earth element is predominant. The second magnetic layer has a rare earth-transition metal alloy and has a transition. 22. The magneto-optical recording medium according to claim 17, wherein the magneto-optical recording medium is a magnetic layer in which a sublattice magnetic moment of a metal element is dominant. 23. The signal amount in the low-temperature region in the beam spot formed by the light beam at the time of reproduction is 1/10 or less of the signal amount in the predetermined high-temperature region in the beam spot. 21. The magneto-optical recording medium according to claim 20, wherein 24. In the predetermined high-temperature region in a beam spot formed by the light beam during reproduction, rotation of the polarization plane of the light beam reflected by the first magnetic layer is caused by rotation of the second magnetic layer. 24. The magneto-optical recording medium according to claim 20, wherein the rotation is larger than the rotation of the polarization plane of the light beam reflected by the recording medium. 25. The magneto-optical recording medium according to claim 17, wherein the thickness of the first magnetic layer is 40 nm or less. 26. The magneto-optical recording medium according to claim 17, wherein the first magnetic layer has a thickness of 5 nm or more. 27. The magneto-optical recording medium according to claim 17, wherein the magneto-optical recording medium is irradiated with a light beam.
The information recorded on the magnetic layer is transferred between the first magnetic layer and the second magnetic layer.
A reproducing method for a magneto-optical recording medium for performing reproduction by magnetically coupling with a magnetic layer, wherein in a high-temperature region in the beam spot, the first magnetic layer is a perpendicular magnetization film, and the first magnetic layer is Transferring the information recorded on the second magnetic layer to the first magnetic layer by magnetically coupling the second magnetic layer to the first magnetic layer; The rotation of the polarization plane of the light beam reflected by the magnetic layer and the rotation of the polarization plane of the light beam transmitted through the first magnetic layer and reflected by the second magnetic layer compensate for each other and cancel each other, so that Reproducing information from the magneto-optical recording medium.