JPH1186371A - Magneto-optical recording and reproducing method and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a magneto-optical information recording and reproducing method capable of executing high-density recording and reproducing and a device therefor. SOLUTION: Information is recorded as magnetic domains on the recording assistance layer of a magneto-optical disk 1 laminated with the recording assistance layer 14, a recording layer 15, an adjustment layer 17 and a reproduction layer 17 by impressing the magnetic fields modulated according to the recording information and the recording assistance layer is scanned with a pot for recording, by which the magnetic domains of the recording assistance layer are transferred to the recording layer and the information is recorded. In addition, the magnetic domains of the recording layer are transferred to the transfer layer by scanning with the spot for reproduction and the magnetic domains are expanded by moving the magnetic walls of the transferred magnetic domains, by which the recorded information is reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magneto-optical information reproducing method and apparatus for recording and reproducing information on a magneto-optical recording medium,
In particular, the present invention relates to a method and apparatus capable of high-density recording and reproduction.

[0002]

2. Description of the Related Art In recent years, a high-density magneto-optical medium for recording and reproducing information using a minute light spot has been receiving attention. The magneto-optical medium records magnetic domains, which are information, as perpendicular magnetization in a magnetic thin film using the thermal energy of a semiconductor laser, and reads this information using the magneto-optical effect. Recently, there has been an increasing demand for increasing the recording density of this magneto-optical medium.

In general, the linear recording density of an optical disk such as a magneto-optical medium depends on the laser wavelength of the reproducing optical system and the N of the objective lens.
A (numerical aperture). That is, when the laser wavelength λ of the reproducing optical system and the NA of the objective lens are determined, the diameter of the light spot is determined. Therefore, the size of the reproducible magnetic domain is limited to about λ / 2NA. Therefore, in order to realize a higher density in a conventional optical disk, it is necessary to shorten the laser wavelength of the reproducing optical system or increase the NA of the objective lens. However, there is a limit in improving the laser wavelength and the NA of the objective lens. For this reason, techniques for improving the recording density by devising the configuration of the recording medium and the reading method have been developed.

For example, Japanese Patent Application Laid-Open No. 2-177148 proposes a method for improving the structure of a recording medium and a recording method. That is, according to the publication, information is recorded on a disk having two or more recording layers by recording the information with a magnetic head and then transferring the information with an optical head.
It is described that information is reproduced by a conventional method. In JP-A-6-290496, a light spot is irradiated on a magneto-optical medium having a plurality of magnetic layers stacked, and a magnetic domain recorded as perpendicular magnetization on a recording layer is transferred to a reproducing layer. A domain wall displacement reproducing method has been proposed in which the domain wall of the magnetic domain transferred to the reproducing layer is moved to make the domain larger than the magnetic domain of the recording layer for reproduction.

[0005]

However, in Japanese Patent Application Laid-Open No. 2-177148, the size of a magnetic domain to be recorded in the linear density direction is determined by a magnetic head, and is 0.1 μm.
It is possible to record magnetic domains of a degree or less at a high speed, but since reproduction is performed using a conventional method, λ / 2
When the wavelength λ is 650 nm and the NA is 0.6, for example, the resolution is only about 0.54 μm, and the recording ability cannot be fully utilized.

In Japanese Patent Application Laid-Open No. 6-290496, it is possible to reproduce a magnetic domain whose size in the linear density direction is about 0.1 μm or less, but a conventional magnetic field modulation method is used as a recording method. Therefore, a magnetic domain having a size in the linear density direction of about 0.1 μm or less could not be stably recorded. Furthermore, even if recording is possible, the shape of the magnetic domain is in the shape of an arrow blade, which is inconsistent with the shape of the light spot for reproduction, which has a problem that reproduction is adversely affected.

An object of the present invention is to provide a magneto-optical information recording / reproducing method and apparatus capable of high-density recording and reproduction in view of the above conventional problems.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a recording auxiliary layer exchange-coupled to each other, a recording layer having a higher holding power at room temperature and a lower Curie temperature than the recording auxiliary layer, and an adjusting layer for adjusting the exchange coupling force. And a method for recording and reproducing information on a magneto-optical recording medium comprising a transfer layer and a recording layer, wherein the recording information is applied to the recording auxiliary layer by applying a magnetic field modulated according to the recording information to the recording medium. Is temporarily recorded as a magnetic domain, the magnetic domain recorded on the recording auxiliary layer is transferred to the recording layer by scanning a recording light spot on the recording medium to record information, and a reproduction spot is recorded on the recording medium. A magnetic domain recorded on the recording layer is transferred to the reproducing layer by scanning, and recorded information is reproduced by moving a domain wall of the transferred magnetic domain to expand the magnetic domain. It is achieved by recording and reproducing method.

Another object of the present invention is to provide a recording auxiliary layer exchange-coupled to each other, a recording layer having a larger holding force at room temperature and a lower Curie temperature than the recording auxiliary layer, an adjusting layer for adjusting the exchange coupling force, and a transfer layer. An apparatus for recording and reproducing information on a laminated magneto-optical recording medium, wherein the recording information is temporarily recorded as magnetic domains on the recording auxiliary layer by applying a magnetic field modulated according to the recording information to the recording medium. Means for recording, means for recording information by transferring magnetic domains recorded on the recording auxiliary layer to the recording layer by scanning a recording light spot on the recording medium, and reproducing a spot on the recording medium. Means for transferring magnetic domains recorded on the recording layer to the reproducing layer by scanning, and moving the magnetic domain walls of the transferred magnetic domains to expand the magnetic domains to reproduce recorded information. It is achieved by a magneto-optical recording and reproducing apparatus according to claim and.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration of one embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a magneto-optical disk serving as an information recording medium, which rotates at a predetermined speed by driving a spindle motor 2. The magneto-optical disk 1 is introduced into or discharged from the apparatus by a mechanism (not shown). Reference numeral 3 denotes a control circuit that controls each unit in the apparatus, and is connected to an information processing apparatus such as an external computer via an interface controller 4. The control circuit 3 controls transmission and reception of information to and from the information processing apparatus, and controls recording and reproduction operations on the magneto-optical disk 1.

The optical head 5 is a recording / reproducing head for recording / reproducing information by irradiating the magneto-optical disk 1 with a light beam. The optical head 5 includes a semiconductor laser, an objective lens for narrowing a laser beam, a photodetector for detecting light reflected from the disk 1, and the like. The magnetic head 6 is provided to face the optical head 5 with the magneto-optical disk 1 interposed therebetween, and applies a magnetic field to the magneto-optical disk 1 when recording information. The optical head and magnetic head control circuit 7 is a control circuit for controlling the position of the light beam emitted from the optical head 5 to the magneto-optical disk 1 and the position of the magnetic head 6.

That is, the optical head and magnetic head control circuit 7
Performs seek control between the optical head 5 and the magnetic head 6, performs focus control such that a light beam from the optical head 5 is focused on the medium surface of the rotating magneto-optical disk 1,
Tracking control is performed so that the light beam from the optical head 5 follows the information track. The spindle motor controller 10 is a control circuit for controlling the rotation of the magneto-optical disk 1 based on the control of the control circuit 3.

An information recording circuit 8 records information on the magneto-optical disk 1 under the control of the control circuit 3, and an information reproducing circuit 9 records information on the magneto-optical disk 1 based on a read signal from the optical head 5. Is a circuit for reproducing. Here, when a recording command is issued from the information processing device, the control circuit 3 controls each unit to move the optical head 5 and the magnetic head 6 to a target information track, and also transmits an information signal transmitted from the information processing device. Is transferred to the information recording circuit 8. Information recording circuit 8
The information signal is modulated, the magnetic head 6 is driven by the modulated signal, and a constant drive current for recording is supplied to the semiconductor laser in the optical head 104 to record information on the information track. The information recording operation will be described later in detail.

On the other hand, when a reproduction command is issued from the information processing device, the control circuit 3 controls each unit to move the optical head 5 to a target track. Further, the control circuit 3 controls the information recording circuit 8 to supply a constant drive current for reproduction to the semiconductor laser in the optical head 5 and to apply a reproduction light beam from the optical head 5 to the information track of the magneto-optical disk 1. Scan. At this time, the optical head 5 detects reflected light from the magneto-optical disk 1, and the information reproducing circuit 9 performs predetermined signal processing based on the read signal to reproduce recorded information. The reproduced data is transferred to an external information processing device via the interface controller 4 under the control of the control circuit 3.

FIG. 2 shows a specific layer structure of the magneto-optical disk 1. In FIG. 2, 13 is a protective layer, and 14 is a first magnetic layer. The first magnetic layer 14 is a recording auxiliary layer for temporarily recording information as magnetic domains by a modulation magnetic field of the magnetic head 6 (hereinafter, the first magnetic layer is referred to as a recording auxiliary layer). Reference numeral 15 denotes a second magnetic layer, which is a recording layer that transfers a part of the magnetic domain temporarily recorded in the recording auxiliary layer 14 by the heat of the light spot and records it as a minute magnetic domain (hereinafter, referred to as a recording layer). Reference numeral 16 denotes a third magnetic layer.
This is an adjustment layer for adjusting the exchange coupling force with the magnetic layer 17 (hereinafter, referred to as an adjustment layer). The fourth magnetic layer 17 transfers the magnetic domain recorded on the recording layer 15 by utilizing the function of the adjustment layer 16 and the heat distribution by the light spot, and further moves the domain wall of the transferred magnetic domain to form the recording layer. This is a reproducing layer for reproducing data with a size larger than 15 magnetic domains (hereinafter referred to as a reproducing layer). 18 is a protective and interference layer, and 19 is a transparent substrate. The magnetic layers 14 to 17 are exchange-coupled to each other, and the layers 13 to 18 are sequentially laminated on the substrate 19.

Here, assuming that the magneto-optical disk 1 having such a layer structure is moving in the direction of arrow A, the light spot by the optical head 5 is inclined from the substrate 19 side, and the objective in the optical head 5 is The light is irradiated by the lens 12 as a light spot having a diameter of about 1 μm. This light spot scans on a target track under the servo control of the optical head and magnetic head control circuit 7. On the other hand, the magnetic head 6 is in close contact with the side opposite to the substrate side and includes at least a track scanned by a light spot and is located at a position slightly ahead of the light spot. The distance between these heads must be at least as long as the range affected by the heat by the light spot and the range affected by the magnetic field by the magnetic head 6 do not overlap. Further, it is desirable that the magnetic head 6 and the optical head 5 are integrated, and that the tracking operation of the magnetic head 6 follows the tracking operation of the optical head 5.

FIG. 3 shows the recording auxiliary layer 14 of the magneto-optical disk 1.
4 shows the characteristics of the coercive force with respect to the temperature of the recording layer 15. A curve 20 shows the characteristics of the recording auxiliary layer 14. That is, the recording auxiliary layer 14 has a small coercive force Hc1 at room temperature,
It has a high Curie temperature Tc1. On the other hand, a curve 21 shows the characteristics of the recording layer 15. That is, the recording layer 15 has a larger coercive force Hc2 at room temperature than the recording auxiliary layer 14, and has a lower Curie temperature Tc2. Also, the Tcom of the curve 20
p is the compensation point temperature.

Next, a method for recording information on the magneto-optical disk 1 will be described. First, FIG. 4A is a sectional view of the recording auxiliary layer 14 and the recording layer 15 of the magneto-optical disk 1. The characteristics of each layer are as described in FIG. FIG. 4B is a plan view of the recording auxiliary layer 14. To record information, a magnetic field modulated according to the recording information is generated from the magnetic head 6 and applied to the magneto-optical disk 1. At this time, assuming that the maximum magnitude of the absolute value of the magnetic field on the magnetic layer is an appropriate value between the coercive forces Hc1 and Hc2 of the recording auxiliary layer 14 and the recording layer 15 at room temperature, according to the modulation of the magnetic field, Information is temporarily recorded in the recording auxiliary layer 14 as a vertical magnetic domain sequence due to a difference between upward magnetization and downward magnetization. However, since the intensity of the applied magnetic field is equal to or lower than the coercive force, the recording layer 15 is not affected and the previous state is maintained.

The size (linear density) in the track direction of the magnetic domain temporarily recorded by the magnetic head 6 can be on the order of submicron, and is smaller than the conventional size recorded by the optical head 5. can do. Further, by setting the size in the direction perpendicular to the track to several to several tens of tracks, the tracking accuracy required for the magnetic head 6 can be relaxed. FIG.
In (b), reference numerals 22a, 22b, and 22c indicate respective tracks, and the width thereof is about 1 μm. In FIG. 4B, the magnetic domains temporarily recorded by the magnetic head 6 are hatched upward and black in the downward direction. Now, assuming that the track to be recorded is 22b, the magnetic domain row is approximately 22
The data is temporarily recorded by overwriting the previous magnetic domain row over several to several tens of tracks around the center b.

FIG. 5A is a sectional view of the recording auxiliary layer 14 and the recording layer 15 of the magneto-optical disk 1 as in FIG. 4A. FIG. 5A shows a case where a light spot is formed on the target track 22 on the magneto-optical disk 1 on which information is temporarily recorded as shown in FIG.
3B shows a state immediately after the scanning on B. FIG. 5B is also a plan view of the recording auxiliary layer 14. Here, reference numeral 23 denotes a light spot from the optical head 5, and a hatched portion of 24 denotes a region where the temperature of the light spot 23 is raised to a certain level or more. FIG. 5C is a plan view of the recording layer 15.

Here, after the magnetic domain array is temporarily recorded on the recording auxiliary layer 14 by the magnetic head 6, the light spot 23 by the optical head 5 is scanned on the target track 22b as shown in FIG. The rising temperature of the magnetic layer at this time is determined by the Curie temperatures Tc1 and Tc1 of the recording auxiliary layer 14 and the recording layer 15, respectively.
When the light intensity is controlled in accordance with the rotation speed of the magneto-optical disk 1 so as to reach an appropriate temperature during the period c2, the light spot 23
2 heated to Curie temperature Tc2 or higher by
In the 24 region on 2b, the magnetization of the recording layer 15 disappears,
The previously recorded information is erased. Then, when the light spot 23 passes and the heat falls below the Curie temperature Tc2, a part of the magnetic domain sequence temporarily recorded in the recording auxiliary layer 14 is transferred. That is, a part of the magnetic domain sequence temporarily recorded over several to several tens of tracks in FIG. 4B is transferred and recorded on the target track of the recording layer 15 as shown in FIG. 5C. Here, as described above, the recording auxiliary layer 14 has a compensation point at room temperature or higher, and has a large holding force at the temperature during transfer, so that stable transfer can be performed.

The final magnetic domain shape thus recorded is:
As shown in FIG. 5C, the shape of the magnetic domain is approximately square, and the size (linear density) of the magnetic domain in the track direction is a submicron size determined by the capability of the magnetic head 6. Here, it is assumed that a magnetic domain having a size of 0.1 μm or less, which cannot be reproduced by a conventional optical head, is recorded. On the other hand, the size of the magnetic domain in the direction perpendicular to the track is determined by the diameter of the light spot, and is about 1 μm. Note that curve 2 shown in FIG.
Assuming that the temperature at the intersection of 0 and 21 is Two, the temperature of the magnetic layer at the time of recording may be between Two and Tc1, and the temperature of the magnetic layer at the time of reproduction may be two or less.

Next, a method of reproducing a magnetic domain sequence having a high linear density recorded as described above will be described with reference to FIGS. FIG. 6A is a cross-sectional view of the recording layer 15, the adjustment layer 16, and the reproducing layer 17, and FIG. 6B is a plan view seen from the reproducing layer 17. Numeral 24 denotes a light spot for reproduction, and numeral 26 denotes a target track on the magneto-optical disk 1 to be reproduced. Arrows in each of the recording layer 15, the adjustment layer 16, and the reproduction layer 17 indicate the direction of the atomic spin. Twenty-five domain walls are formed in regions where the spin directions are opposite to each other.

FIG. 6C shows a temperature distribution formed on the magneto-optical disk 1. Reproduction of information according to the present embodiment is possible in principle using one light spot or two light spots, but here, for the sake of simplicity, two light spots are used. Playback shall be performed. FIG. 6 shows only light spots that contribute to the reproduction signal. The second light spot (not shown) is shown in FIG.
Irradiation is performed to form the temperature distribution of (c). Now, it is assumed that the temperature on the magneto-optical disk 1 is Ts near the Curie temperature of the adjustment layer 16 at the position Xs.

FIG. 6D is a graph showing the distribution of the domain wall energy density σ1 of the reproducing layer 17 corresponding to the temperature distribution of FIG. 6C. When the gradient of the domain wall energy density σ1 exists in the X direction, a force F1 shown in the drawing acts on the domain wall of each layer existing at the position X. This F1 acts to move the domain wall to the lower domain wall energy. Since the reproducing layer 17 has a small domain wall coercive force and a large domain wall mobility, the domain wall is easily moved by this force F1 alone. However, the temperature of the magneto-optical disk 1 is still lower than Ts in the area before the position Xs (the right side in FIG. 6), and the recording layer 1 is exchanged with the recording layer 15 having a large domain wall coercive force.
5, the domain wall in the reproduction layer 17 is also fixed at a position corresponding to the domain wall position.

Here, as shown in FIG.
Assume that one of the five is at position Xs on the medium. Also, position X
s, the temperature of the magneto-optical disk 1 rises to Ts near the Curie temperature of the adjustment layer 16, and the reproducing layer 17 and the recording layer 1
It is assumed that the exchange coupling with No. 5 is broken. As a result, the domain wall 25 in the reproducing layer 17 instantaneously moves to a region where the temperature is higher and the domain wall energy density is lower as indicated by the arrow. Therefore, when the light spot 24 for reproduction passes, the atomic spins of the reproduction layer 17 in the spot are all aligned in one direction as shown in FIG.

Then, the domain wall 25 instantaneously moves with the movement of the medium, and the directions of the atomic spins in the light spot are reversed, and are all aligned in one direction. A reproduction signal of the reflected light from the magneto-optical disk 1 is detected by a conventional differential detection optical system.
However, in this case, the signal reproduced by the light spot always has a constant amplitude irrespective of the size of the magnetic domain recorded on the recording layer 15, and is free from the problem of waveform interference caused by the optical diffraction limit. You. That is, it is possible to reproduce a magnetic domain smaller than the resolution limit of about λ / 2NA determined by the laser wavelength λ and the NA of the objective lens, and it is possible to reproduce a submicron linear density.

FIG. 7 shows an example of the configuration of an optical head when two spots are used. Reference numeral 27 denotes a recording / reproducing semiconductor laser having a wavelength of, for example, 780 nm. Reference numeral 29 denotes a semiconductor laser for heating, which has a wavelength of, for example, 1.3 μm. Both are arranged so as to be inclined with respect to the recording medium by P-polarized light. Generally, the cross-sectional shape of a laser beam diverging from a semiconductor laser is elliptical. Conventionally, this shape is formed into a circular spot on a recording medium by using a beam forming prism or a substantially circular opening. The laser beams emitted from the semiconductor lasers 27 and 28 are made substantially circular by a beam shaping means (not shown), and then are made into parallel light beams by collimator lenses 28 and 30 respectively.

31 transmits 100% of 780 nm light,
The dichroic mirror is designed to reflect 1.3 μm light at 100%. A polarization beam splitter 32 transmits 70 to 80% of P-polarized light and reflects almost 100% of S-polarized light, which is a component perpendicular thereto. The parallel light beams converted by the collimator lenses 28 and 30 enter the objective lens 33 via the dichroic mirror 31 and the polarizing beam splitter 32. At this time, 78
The luminous flux of 0 nm is made larger with respect to the size of the aperture of the objective lens 33, and the luminous flux of 1.3 μm is made smaller with respect to the size of the aperture of the objective lens 33.

Therefore, even when the same objective lens 33 is used, the NA of the lens is small for a light beam of 1.3 μm, and the size of the light spot on the magneto-optical disk 1 is 78.
It is larger than that of 0 nm. The light reflected from the disk 1 again passes through the objective lens 33 to become a parallel light beam, is reflected by the polarization beam splitter 32, and is obtained as a light beam 35. After wavelength separation or the like is performed from the light beam 35 by an optical system (not shown), a servo error signal and an information reproduction signal are obtained in the same manner as in the conventional method.

FIG. 8A shows the relationship between the recording / reproducing light spot and the heating light spot on the magneto-optical disk 1 of the apparatus shown in FIG. In FIG. 8A, reference numeral 36 denotes a wavelength 7
An 80 nm recording / reproducing light spot, 37 has a wavelength of 1.3.
It is a light spot for heating of μm. Numeral 38 denotes a domain wall of a magnetic domain recorded on the land 39, and numeral 40 denotes a groove. Also 4
Reference numeral 1 denotes a region where the temperature has risen due to the heating light spot 37. Thus, the land 39 between the grooves 40
Above, by combining the recording / reproducing light spot 36 and the heating light spot 37, a temperature gradient as shown in FIG. 8B can be formed on the rotating disk 1. Temperature gradient and light spot 36 for recording and reproduction
Is the same as that shown in FIG. 6, and thereby domain wall displacement reproduction can be performed.

Specific materials for each layer of the magnetic layer group include:
An amorphous alloy made of a combination of at least one of a transition metal and a rare earth metal can be used. For example, transition metals are mainly Fe, Co, Ni, and rare earth metals are mainly Gd, Tb, Dy, Ho, Nd, and Sm.
Typical combinations include TbFeCo, GdTbF
e, GdFeCo, GdTbFeCo, GdDyFeC
o. Further, in order to improve corrosion resistance, Cr, Mn,
A small amount of Cu, Ti, Al, Si, Pt, In or the like may be added. The material of the recording auxiliary layer 14 is Co-Cr.
System, Ba-Ferrite system, MnBi system, iron oxide system,
Co-doped iron oxide, CrO ₂ , Ni-Co, Fe
A magnetic material such as -Ni-Co or a Heusler alloy such as PtMnSb may be used.

The substrate 19 is made of glass, polycarbonate,
It is a plastic material such as polymethyl methacrylate and may be thick and hard, or may be thin and flexible. As protective layers 13 and 18, Si ₃ N ₄ , AlN, SiO ₂ , SiO, Zn
A transparent dielectric material such as S, MgF ₂ can be used. In addition, Al, AlTa, AlTi, Al
A thermal property may be adjusted by adding a metal layer such as Cr or Cu.

Next, the method using two beams as the reproducing method has been described so far. A domain wall displacement reproducing method using one beam will be described with reference to FIG. The one-beam optical head can be configured by omitting the semiconductor laser 29 for heating, the collimator lens 30 corresponding thereto, and the dichroic mirror 31 for combining two light beams in the optical head of FIG.

FIG. 9A is a sectional view of the recording layer 15, the adjustment layer 16, and the reproducing layer 17, and FIG. 9B is a plan view seen from the reproducing layer 17. 42 is a light spot for recording and reproduction. Here, the light spot is an elliptical light spot. The reason why the elliptical light spot is used is that, in this embodiment, even if the beam is large in the direction parallel to the track, the beam density is not changed from the circular light spot in terms of linear density, and the beam shaping of the light beam from the semiconductor laser by the optical head is performed. This is because omission of an ellipse can provide an elliptical light spot, that is, it is also useful for downsizing the optical head. There is no problem if the light spot shape for recording is also elliptical. Of course, the essence of the present invention does not change even if a circular light spot is used.

When the elliptical light spot 42 is irradiated in this manner, a temperature distribution indicated by an egg-shaped contour line is generated on the disk 1. Similarly, the moving direction of the disk 1 is the direction A in the figure. Similarly, the arrows in each magnetic layer indicate the direction of the atomic spin, and domain walls such as 43 are formed in the regions where the spin directions are opposite to each other. The hatched area 44 is a high-temperature area, which is higher than the Curie point temperature of the reproducing layer 17. Therefore, the magnetization of the reproducing layer 17 disappears in the region of the high-temperature portion 44, and the domain wall does not move in the high-temperature portion 44.

A portion 45 around the high temperature portion 44 is a medium temperature portion. The medium temperature is a region that is equal to or higher than the Curie point temperature of the adjustment layer 16 and equal to or lower than the Curie point temperature of the reproducing layer 17. When the domain walls 46 and 47 of the magnetic domain recorded on the recording layer 15 reach the boundary between the low-temperature region and the medium-temperature portion 45, the domain wall 46 is in the direction A in the drawing and the domain wall 47 is in the direction opposite to the direction A in the drawing. Each moves toward the high temperature part. Here, the area in which the domain wall of 47 moves is controlled by the size of the high-temperature portion 44 and is driven out of the irradiation area of the light spot 42 contributing to reproduction, whereby leakage to a reproduced signal caused by the movement of the domain wall of 47 is performed. It is possible to eliminate the interference and selectively reproduce only the influence on the reproduction signal caused by the movement of the domain wall 46.

[0038]

As described above, according to the present invention, after a modulation magnetic field is applied to the magneto-optical recording medium to temporarily record on the recording auxiliary layer, the light spot is scanned to change the magnetic domain of the recording auxiliary layer. By recording information by transferring the information to a medium, high-density recording becomes possible.
Magnetic domains of about μm or less can be stably recorded. Also, by reproducing the spot by scanning the reproducing spot and moving the domain wall of the magnetic domain to expand the magnetic domain, information of high density recording can be easily reproduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a sectional view showing a layer configuration of a magneto-optical disk used in the embodiment of FIG.

FIG. 3 is a diagram showing characteristics of a magneto-optical disk.

FIG. 4 is a diagram for explaining temporary recording by a magnetic head in an information recording process of the embodiment of FIG. 1;

FIG. 5 is a diagram for explaining transfer by an optical head in an information recording process according to the embodiment of FIG. 1;

FIG. 6 is a diagram for explaining information reproduction according to the embodiment of FIG. 1;

FIG. 7 is a diagram showing an example of the configuration of an optical head when reproducing with two beams according to the embodiment of FIG. 1;

FIG. 8 is a diagram for explaining an operation when reproducing with two beams.

FIG. 9 is a diagram for explaining an operation when reproducing with one beam.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magneto-optical disk 3 Control circuit 5 Optical head 6 Magnetic head 7 Optical head and magnetic head control circuit 8 Information recording circuit 9 Information reproducing circuit 13 Protective layer 14 First magnetic layer (recording auxiliary layer) 15 Second magnetic layer ( Recording layer) 16 Third magnetic layer (adjustment layer) 17 Fourth magnetic layer (reproducing layer) 19 Substrate

Claims (2)

[Claims] 1. A magneto-optical layer comprising: a recording auxiliary layer exchange-coupled to each other; a recording layer having a higher holding force at room temperature than the recording auxiliary layer and a lower Curie temperature; an adjustment layer for adjusting the exchange coupling force; and a transfer layer. A method of recording information on a recording medium and reproducing the information, wherein the recording information is temporarily recorded as magnetic domains on the recording auxiliary layer by applying a magnetic field modulated according to the recording information to the recording medium. The magnetic domain recorded on the recording auxiliary layer is transferred to the recording layer by scanning a recording light spot to record information, and the reproduction spot is scanned on the recording medium to record on the recording layer. A magneto-optical recording / reproducing method, wherein the recorded magnetic domain is transferred to the reproducing layer, and the domain wall of the transferred magnetic domain is moved to expand the magnetic domain, thereby reproducing recorded information. 2. A magneto-optical device comprising: a recording auxiliary layer exchange-coupled to each other; a recording layer having a larger holding force at room temperature than the recording auxiliary layer and a lower Curie temperature; an adjustment layer for adjusting the exchange coupling force; A device that records information on a recording medium and reproduces the information, and a unit that temporarily records the recording information on the recording auxiliary layer as a magnetic domain by applying a magnetic field modulated according to the recording information to the recording medium; Means for recording information by transferring magnetic domains recorded on the recording auxiliary layer to the recording layer by scanning a recording light spot on a recording medium, and by scanning a reproduction spot on the recording medium, Means for transferring magnetic domains recorded on the recording layer to the reproducing layer, moving domain walls of the transferred magnetic domains to expand the magnetic domains, and reproducing recorded information. Recording and playback device.