JP2000173125A - Magneto-optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magneto-optical recording medium which enables magnetic induction super-high resolution reproduction by completely masking the marks adjacent the marks to be reproduced. SOLUTION: The magneto-optical recording medium includes a transparent substrate, a magnetic reproducing layer 18' laminated on the transparent substrate, a magnetic control layer 20' laminated on the magnetic reproducing layer 18' and a magnetic recording layer 22 laminated on the magnetic control layer 20'. The magnetic reproducing layer 18' has an axis of easy magnetization in a direction perpendicular to the film plane at room temperature. The magnetic control layer 20' has the axis of easy magnetization in an intra-surface direction at room temperature. The magnetic recording layer 22 has the axis of easy magnetization in a perpendicular direction. A low- temperature region where the magnetization of the reproducing layer 18' faces the perpendicular direction, an intermediate temperature region where the magnetization of the recording layer 22 is transferred to the reproducing layer 18' via the control layer 20' by exchange bonding and a high-temp. region above the Curie temperature of the control layer 20' are formed within a laser spot by irradiation with prescribed reproduction powder. Upspin masks are formed in the low-temp. region and the high- temp. region. An apertures are formed between both masks in order to read out the magneto-optical signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a high-density magneto-optical recording medium.

[0002] Magneto-optical disks are known as high-density recording media, but there is a demand for higher densities as the amount of information increases. Higher density can be achieved by reducing the interval between recording marks, but its recording and reproduction are limited by the size (beam spot) of the light beam on the medium.

If only one recording mark exists in a beam spot, an output waveform corresponding to "1" or "0" can be observed as a reproduction signal depending on whether or not there is a recording mark.

[0004] However, if a plurality of recording marks are provided so as to be present in a beam spot so that the reproduction output does not change even if the beam spot on the medium moves, the output waveform becomes a straight line. The presence or absence of the recording mark cannot be identified.

In order to reproduce such a small recording mark having a period equal to or smaller than the beam spot, the beam spot may be narrowed down. However, the size of the beam spot depends on the wavelength λ of the light source and the numerical aperture NA of the objective lens. And cannot be narrowed down sufficiently.

[0006]

2. Description of the Related Art Recently, a reproducing method using a magnetic induction super-resolution technique for reproducing a recording mark below a beam spot using the existing optical system as it is has been proposed. This is a reproducing method in which when one mark in a beam spot is reproduced, another mark is masked to increase the reproducing resolution.

For this reason, in a super-resolution disk medium, in addition to a recording layer for recording a mark, a mask layer or a reproduction layer for hiding another mark so that only one mark is reproduced during signal reproduction. Is required at a minimum.

A magneto-optical recording medium using a perpendicular magnetization film as a reproducing layer has been proposed in Japanese Patent Application Laid-Open No. 3-88156. However, the prior art described in this publication requires an initialization magnetic field of about several kilo-Oersteds to initialize the reproducing layer, so that there is a problem that the device cannot be miniaturized.

On the other hand, a magneto-optical recording medium using a magnetic layer having an easy axis of magnetization in an in-plane direction at room temperature in a reproducing layer and having an easy axis of perpendicular magnetization at a predetermined temperature or higher is disclosed in Japanese Patent Laid-Open No. Hei 5-8171.
No. 7 is proposed.

Referring to FIG. 7, a brief description will be given of the reproduction principle of the prior art. As shown in FIG. 7C, the magneto-optical disk 2 has a magnetic reproducing layer 6 and a magnetic recording layer 8 on a transparent substrate 4.
Are laminated.

The magnetic reproducing layer 6 has an easy axis in the in-plane direction at room temperature. However, when the reproducing power is applied and the temperature exceeds a predetermined temperature, the easy axis changes in the vertical direction. The magnetic recording layer 8 is a perpendicular magnetization film. Reference numeral 10 denotes a light beam.

Since the intensity distribution of the light beam has a Gaussian distribution as shown in FIG. 7 (A), when the disk is stationary, the temperature distribution on the disk is higher at the center than at the periphery. Has become.

However, in practice, since the disk 2 is rotating in the direction of arrow R, the temperature distribution on the disk is as shown in FIG.
As shown in (B), the front side in the disk movement direction in the beam spot has a high temperature.

Since the temperature distribution is thus generated, the Kerr rotation angle of the reflected light is almost zero because the easy axis of magnetization of the magnetic reproducing layer 6 is oriented in the in-plane direction in a low temperature region in the beam spot. Becomes In the high temperature region, the axis of easy magnetization of the magnetic reproducing layer 6 changes from the in-plane direction to the vertical direction.

At this time, the perpendicular magnetization of the magnetic reproducing layer 6 is coupled to the magnetization of the magnetic recording layer 8 by exchange force and aligned with the magnetization direction of the magnetic recording layer 8. Can be transferred to The size of the transfer area can be changed by the power of the reproducing laser beam or the rotation of the disk.

By controlling the size of the mask of the magnetic reproducing layer so that only one recording mark can be reproduced, the same effect as substantially reducing the area of the beam spot can be obtained. The resolution is improved and high-density recording / reproduction can be realized.

[0017]

As described above, the intensity distribution of the laser beam 10 applied to the disk 2 has a Gaussian distribution, and the disk 2 is rotating in the direction of arrow R. A low-temperature region and a high-temperature region are generated on 6, and the high-temperature region is shifted downstream, that is, rearward of the beam spot formed on the disk.

As described above, since the high-temperature region in the beam spot for reproducing information shifts to the downstream side, the intensity of the laser beam becomes relatively weak, and the large light in the prior art described in Japanese Patent Application Laid-Open No. 5-81717. There is a problem that a magnetic signal cannot be obtained.

Further, since the optical mask is formed only on the upstream side in the beam spot, the size of the opening for reproducing information cannot be reduced too small.

Accordingly, an object of the present invention is to provide a high-density magneto-optical recording medium capable of accurately recording a smaller mark than before and reproducing the same with a larger magneto-optical signal than before.

[0021]

According to the present invention, there is provided a magneto-optical recording medium comprising a multilayer magnetic film containing a rare earth metal and a transition metal as main components, and having an easy axis of magnetization perpendicular to the film surface. A reproducing layer, and an easy axis of magnetization in an in-plane direction at room temperature provided on the reproducing layer, wherein the rare earth magnetic moment is dominant, and at least Gd is contained as a rare earth metal, Fe is contained as a transition metal, and a compensation temperature is included. Not control layer,
A recording layer having an easy axis of magnetization perpendicular to a film surface provided on the control layer, wherein the reproducing layer, the control layer,
The Curie temperature of the recording layer is set to Tc1, Tc2, Tc, respectively.
3, and the coercive forces of the reproducing layer and the recording layer at room temperature are Hc1 and Hc3, respectively, the Curie temperatures of the magnetic layers satisfy the relationship of Tc1> Tc2, Tc3> Tc2, and the reproducing layer and the recording layer And a coercive force at room temperature satisfying the relationship of Hc3> Hc1.

When reproducing information recorded on the magneto-optical recording medium of the present invention having a reproducing layer, a control layer, and a recording layer, a smaller temperature gradient is generated by using a temperature gradient generated in a beam spot formed on the recording medium. It is characterized by reproducing marks accurately.

In a region where the temperature is low in the beam spot, the magnetization of the reproducing layer is oriented in the direction of the reproducing bias magnetic field to form an up spin mask or a down spin mask. In a high temperature region higher than the Curie temperature of the control layer, the magnetization of the control layer is reduced. It disappears, and the magnetization of the reproducing layer faces the direction of the reproducing bias magnetic field to form an up spin mask or a down spin mask.

In the intermediate temperature region (opening), the magnetization direction of the recording layer is transferred to the reproducing layer via the control layer, and the information recorded on the recording layer can be reproduced.

That is, when the magneto-optical output is differentially detected, the low temperature region and the high temperature region in the beam spot act as a mask, and the magneto-optical signal is not read out in this region, but only in the intermediate temperature region. A magneto-optical signal can be read. Therefore, a mark having a size equal to or smaller than the diffraction limit of the laser wavelength can be accurately read.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of a magneto-optical recording medium according to an embodiment of the present invention will be described with reference to FIG. Reference numeral 12d denotes a magneto-optical recording medium, which usually has a disk shape. Si is formed on a transparent substrate 14 such as glass by sputtering, for example.
A dielectric layer 16 made of N or the like is laminated. The dielectric layer 16 prevents oxidation and corrosion of the magnetic layer laminated thereon.

As the transparent substrate 14, a resin such as polycarbonate, polymethyl methacrylate, and amorphous polyolefin can be used. Also, the dielectric layer 16
Metal nitrides such as AlN, SiO2, Al2O
Metal oxides such as 3 and metal sulfides such as ZnS can be employed.

The magnetic reproducing layer 1 formed of a rare earth-transition metal amorphous alloy film such as GdFeCo on the dielectric layer 16
8 'are stacked. The magnetic reproducing layer 18 ′ has an easy axis of magnetization perpendicular to the substrate 14.

On the magnetic reproduction layer 18 ', a magnetic control layer 20' formed of a rare earth-transition metal amorphous alloy film such as GdFeCo is laminated. The magnetic control layer 20 'has an easy axis of magnetization in the in-plane direction at room temperature.

On the magnetic control layer 20 ', a magnetic recording layer 22 made of a rare earth-transition metal amorphous alloy film such as TbFeCo is laminated. The magnetic recording layer 22 has an easy axis of magnetization perpendicular to the substrate 14.

Reproducing layer 18 ', control layer 20' and recording layer 2
Assuming that the Curie temperatures of No. 2 are Tc1, Tc2, and Tc3, respectively, the Curie temperatures of the respective magnetic layers satisfy the relations of Tc2 <Tc1 and Tc2 <Tc3.

Assuming that the coercive forces of the reproducing layer 18 'and the recording layer 22 at room temperature are Hc1 and Hc3, Hc1 <H
It is necessary to satisfy the relationship of c3.

The reproducing layer 18 'can be formed of a TbGdFeCo amorphous alloy film, and the control layer 20' is formed of GdF
e can be formed from an amorphous alloy film. Preferably, a non-magnetic material selected from the group consisting of Si, Al, and Ti is added to control layer 20 '.

The protective film 24 is laminated on the magnetic recording layer 22 to complete the magneto-optical recording medium 12d. This protective film 24
Is provided for the purpose of preventing a substance such as water, oxygen or a halogen element from entering the air and protecting the magnetic recording layer 22.

The protective film 24 is made of a metal nitride such as SiN and AlN, a metal oxide such as SiO2 and Al2O3, and ZnS.
And the like.

Referring to FIG. 2, there is shown a schematic diagram of a magneto-optical disk drive which can be employed in the information reproducing method of the present invention. The magneto-optical disk 30 is configured by laminating a three-layer magnetic layer 28 on the transparent substrate 14. The magneto-optical disk 30 is rotated by a spindle motor 32.

Reference numeral 34 denotes an electromagnet driven by an electromagnet drive circuit 36, which applies a bias magnetic field in a predetermined direction to the magneto-optical disk 30. The direction of the bias magnetic field is switched between upward and downward depending on the direction of the current flowing through the electromagnet 34.

Alternatively, a small permanent magnet that generates a magnetic field of about several hundred Oersteds can be substituted for 34. In this case, the direction of the bias magnetic field is switched by rotating the S and N poles of the magnet by 180 °.

A data signal to be written is generated by the signal generation circuit 38 and input to the laser drive circuit 40. Thereby, the laser drive circuit 40 modulates and drives the laser diode 42 according to the data signal.

The laser beam generated by the laser diode 42 is collimated by a collimator lens 44, passes through a beam splitter 46, and is focused on the magnetic layer 28 of the magneto-optical disk 30 by an objective lens 48.

While applying a bias magnetic field in a predetermined direction by the electromagnet 34, the laser diode 42 is driven to irradiate the magnetic layer 28 of the magneto-optical disk 30 with a laser beam, whereby a data signal is written on the disk 30.

On the other hand, when reproducing information (data signal) recorded on the magneto-optical disk 30, the laser diode 42 is driven while applying a bias magnetic field in a predetermined direction by the electromagnet 34 to the magneto-optical disk 30. Irradiate the reproduction beam power.

The reflected light from the magneto-optical disk 30 is collimated by the objective lens 48 and then collimated by the beam splitter 4.
The light reflected by 6 passes through the analyzer 50 and is condensed on the photodetector 54 by the lens 52, and the information recorded on the magneto-optical disk 30 is reproduced as an electric signal.

Next, a data erasing method according to the present embodiment will be described with reference to FIG. The recording medium is irradiated with a laser beam while applying a bias magnetic field Hb downward, to the recording layer 2.
Recording layer 2 by raising the temperature above the Curie temperature of
The magnetization direction of No. 2 is directed downward.

When moving away from the laser beam, the recording medium is cooled to room temperature. At room temperature, the control layer 20 'becomes an in-plane magnetic film, and the reproducing layer 18' and the recording layer 22 are not magnetically coupled. Therefore, the magnetization of the reproducing layer 18 'is aligned downward with a magnetic field as small as the erasing bias magnetic field.

Next, a data writing method according to the present embodiment will be described with reference to FIG. When a strong laser beam is applied only to the recording portion while applying the bias magnetic field Hb in the direction opposite to the erasing direction, that is, upward, only the magnetization of the portion where data is recorded becomes upward.

When moving away from the laser beam, the temperature of the recording medium is lowered to room temperature. At room temperature, the control layer 20 'becomes an in-plane magnetized film, and the reproducing layer 18' and the recording layer 22 are not magnetically coupled. Therefore, the magnetization of the reproducing layer 18 'is aligned upward with a magnetic field as small as the bias magnetic field.

Next, with reference to FIG. 5, a method of reproducing a single mask of data in the present embodiment will be described. In the beam spot 58 irradiated on the track 64, a low-temperature region whose temperature is equal to or lower than Tcopy and a control layer 2 whose temperature is equal to or higher than Tcopy.
A high temperature region not higher than the Curie temperature Tc2 of 0 'is formed.

In a low temperature region in the beam spot 58, an up spin mask 60 is formed.
2 are formed. This state is described in the above-mentioned JP-A-5-817.
No. 17 is similar to the state at the time of data reproduction.
2, a magneto-optical signal can be read out.

When the reproducing laser power is further increased, as shown in FIG. 6, the magnetization of the reproducing layer 18 'is oriented in the direction of the reproducing bias magnetic field Hr in the beam spot 58, and the magnetization of the recording layer 22 is changed by exchange coupling. An intermediate temperature region to be transferred to the control layer 20 'and the reproduction layer 18' and a high temperature region higher than the Curie temperature Tc2 of the control layer 20 'are formed.

In the low temperature region and the high temperature region, the reproducing layer 18 '
Up-spin masks 60 and 68 whose magnetization directions are aligned with the bias magnetic field Hr are formed.
An opening 62 is formed in an intermediate temperature region between 0 and 68.

In the up spin mask section 68, since the recording medium is heated to the Curie temperature Tc2 of the control layer 20 'or higher, the magnetization of the control layer 20' is lost, and
8 'and the recording layer 22 are not magnetically coupled.

Therefore, since the reproducing layer 18 'has a small coercive force at room temperature, its magnetization direction is directed to the direction of the reproducing bias magnetic field Hr. In other words, in a temperature region equal to or higher than the Curie temperature of the control layer 20 ', the magnetization of the reproducing layer 18' is always upward, and a magneto-optical signal is not output and functions as a kind of mask.

Accordingly, an opening 62 which is much smaller than that of the conventional method described in Japanese Patent Application Laid-Open No. 5-81717 can be formed. Further, since the opening 62 is formed at the center of the beam spot where the laser intensity is relatively higher than the end of the beam spot, a large magneto-optical signal can be obtained.

Example 1 TbFeCo and first GdFe were placed in a sputtering apparatus.
Co, second GdFeCo and Si targets and
A polycarbonate substrate having a track pitch of 2 μm was set, and 10
^It was evacuated to ^-5 Pa.

Next, a film having a thickness of 70 nm is formed on the substrate under the following conditions.
Was formed by DC sputtering. This film not only protects the magnetic layer from oxidation, but also has an enhancing effect of increasing the magneto-optical signal.

Gas pressure: 0.3 Pa Sputter gas: argon, nitrogen Partial pressure: argon: nitrogen = 6: 4 Input power: 0.8 kW Next, the inside of the chamber was evacuated again to 10 ⁻⁵ Pa,
A first GdFeC film is formed on the silicon nitride film under the following conditions.
o, the second GdFeCo and TbFeCo were successively formed by DC sputtering in this order.

Gas pressure: 0.5 Pa Sputter gas: Argon Input power: 1 kW The composition, film thickness and magnetic properties of each magnetic layer are as shown in Table 1.

[0059]

[Table 1]

In Table 1, the compensation temperature "-" indicates that there is no compensation temperature below the Curie temperature.

Further, a silicon nitride film having a thickness of 100 nm was formed on the recording layer by the same method as described above. The silicon nitride film serves to prevent the magnetic film from being oxidized.

The recording characteristics of the magneto-optical disk manufactured as described above were examined using the apparatus shown in FIG. The wavelength of the laser used is 780 nm. First, the entire magneto-optical disk was erased, that is, initialized. The laser power at this time was 9 mW, and a downward bias magnetic field was applied.

Information is recorded at a linear velocity of 3 m / sec.
Applying an upward bias magnetic field in the opposite direction to that of the initialization while rotating at a recording power of 4 mW and a frequency of 7.
The measurement was performed at 5 MHz and a light emission duty ratio of 26%. The length of the mark recorded on the disk is about 0.4 μm.

Next, the reproduction characteristics of this magneto-optical disk were examined. The bias magnetic field for reproduction applied at this time was upward. With a reproduction power of 1.5 mW, no output of a magneto-optical signal with respect to the previously recorded signal was obtained. This is presumably because the entire area of the reproducing layer 18 'forms an up spin mask.

At a reproduction power of 1.6 mW, the magnetization direction of the recording layer 22 was transferred to the reproduction layer 18 'via the control layer 20', and an output of a magneto-optical signal could be obtained. This is because the magnetization direction of the recording layer 22 in the beam spot is controlled by the control layer 20 '.
It is presumed that an area higher than the temperature transferred to the reproduction layer 18 'through the through hole was formed, and an up-spin mask and an opening were formed. The signal-to-noise ratio (C /
N) was 42 dB.

At a reproducing power of 1.7 mW, the magnetization of the recording layer 22 is oriented in the direction of the bias magnetic field, that is, upward, and the diameter of the region (opening) where the control layer 20 ′ exchange-couples with the recording layer 22 is 0.4 μm. 46dB C / N
Could be obtained.

Next, it was examined whether or not the composition of the reproducing layer 18 'could be sufficiently used with another composition. As a result, when the reproducing layer 18 'is made of TbFeCo or DyFeCo, the coercive force is increased, so that the magnetization direction of the reproducing layer 18' cannot be initialized with a magnitude of about the bias magnetic field, and super-resolution reproduction is performed. Could not.

Embodiment 2 In Embodiment 1, a material made of GdFeCo was used for the reproducing layer 18 '. However, the composition margin of the GdFeCo film showing perpendicular magnetic anisotropy is not wide, and it may be difficult to control the composition. Therefore, in this example, an attempt was made to add a small amount of Tb capable of increasing the perpendicular magnetic anisotropy to GdFeCo. The experiment was performed as follows.

TbFeCo, T
A target of bGdFeCo, GdFeCo and Si and a polycarbonate substrate having a track pitch of 1.2 μm were set, and the chamber of the sputtering apparatus was evacuated to 10 ⁻⁵ Pa.

Next, a film having a thickness of 70 nm is formed on the substrate under the following conditions.
Was formed by DC sputtering. This film not only has a role of protecting the magnetic film from oxidation, but also has an enhancing effect of increasing a magneto-optical signal.

Gas pressure: 0.3 Pa Sputter gas: argon, nitrogen Partial pressure: argon: nitrogen = 6: 4 Input power: 0.8 kW Next, the inside of the chamber is evacuated again to 10 ⁻⁵ Pa,
Under the following conditions, TbGdFeCo,
GdFeCo and TbFeCo were successively formed by DC sputtering in this order.

Gas pressure: 0.5 Pa Sputter gas: argon Input power: 1 kW The composition, film thickness and magnetic properties of each magnetic layer are as shown in Table 2.

[0073]

[Table 2]

Further, a silicon nitride film having a thickness of 100 nm was formed on the recording layer by the same method as described above. The silicon nitride film serves to prevent the magnetic film from being oxidized.

The reproduction characteristics of the magneto-optical disk manufactured as described above were examined under the same conditions as in Example 1. The reproducing bias magnetic field applied at this time was directed upward. At a reproduction power of 1.4 mW, no output of a magneto-optical signal with respect to the previously recorded signal was obtained. This is presumably because the entire area of the reproducing layer 18 'forms an up spin mask.

At a reproducing power of 1.5 mW, the magnetization direction of the recording layer 22 was transferred to the reproducing layer 18 'via the control layer 20', and an output of a magneto-optical signal could be obtained. This is because the magnetization direction of the recording layer 22 in the beam spot is controlled by the control layer 20 '.
It is presumed that an area higher than the temperature transferred to the reproduction layer 18 'through the through hole was formed, and an up-spin mask and an opening were formed. The signal-to-noise ratio (C /
N) was 42 dB.

At a reproducing power of 1.6 mW, the reproducing layer 18 '
Is oriented in the direction of the bias magnetic field, that is, in the upward direction. Since the diameter of the region (opening) where the control layer 20 'exchange-couples with the recording layer 22 is about 0.4 μm, the C / N ratio of 46 dB is obtained.
Could be obtained.

This C / N was not different from that of Example 1. This is because the addition of Tb to the reproducing layer 18 'increased the magnetic anisotropy and reduced the noise, but the GdF
It is considered that the addition of Tb to eCo reduced the magneto-optical effect.

Then, these effects cancel each other out, and
This is probably because the same result was obtained. However, Tb
Can increase the composition margin of the reproduction layer 18 '.

Example 3 In order to study the composition of the control layer 20 ', the composition of the control layer 20' was changed to TbFeCo and DyFe
A three-layered film recording medium having Co and GdFeCo changed was prototyped, and its recording / reproducing characteristics were examined. Here, the recording conditions are the same as in the first embodiment. Table 3 shows the results.

[0081]

[Table 3]

This indicates that when the control layer 20 'is made of TbFeCo or DyFeCo, the recording / reproducing characteristics are not good, and the composition of the control layer 20' is GdF
eCo has been found to be suitable.

Further, GdFe suitable for the control layer 20 '
The Co composition was studied. When the control layer 20 ′ was made of GdFeCo, the reproduction characteristics when the Co content was changed were measured in the same manner as in Example 12. Table 4 shows the results.
Shown in

[0084]

[Table 4]

From the results, it was found that the content of Co was 0 to 5 at.
%, The C / N is improved. This is considered to be because the Curie temperature of the control layer 20 'was lowered, and a mask was formed also on the trailing edge of the spot of the laser beam, resulting in a double mask and an increase in resolution.

Example 4 It was found from Example 3 that when the Curie temperature of the control layer 20 'was lowered, a double mask was formed and C / N was improved. Therefore, an attempt was made to add a non-magnetic metal to the control layer 20 'for the purpose of lowering the Curie temperature of the control layer 20'.

A magneto-optical recording medium having a control layer 20 ′ obtained by adding a nonmagnetic element to GdFeCo was prototyped, and its reproduction characteristics were examined. The reproduction characteristics were measured in the same manner as in Example 1. Table 5 shows the results.

[0088]

[Table 5]

From the above results, it was found that it is effective to add a non-magnetic material to the control layer 20 '. Next, the nonmagnetic material to be added to the control layer 20 'was Si, and the change in the reproduction characteristics with respect to the change in the amount of added Si was examined.

Here, the composition and thickness of the reproducing layer 18 ', the control layer 20' and the recording layer 22 are the same as in the first embodiment. That is, the composition of the control layer 20 'is Gd39Fe56Co5. It was decided to add Si to this composition. The amount of Si was determined by changing the number of Si chips placed on the target of the control layer 20 'made of GdFeCo. Table 6 shows the results.

[0091]

[Table 6]

From the results, it was found that the content of Si was 10-60.
It has been found that high C / N can be obtained in a wide range of at%. If the Si content is 70 at% or more, the exchange coupling force between the reproducing layer 18 ′ and the recording layer 22 decreases, so that C
/ N decreases.

[0093]

According to the present invention, a magneto-optical recording medium capable of high-density recording can be provided, and a mark adjacent to a mark to be reproduced can be completely masked to improve reproduction output. It has the effect of being able to. Also, crosstalk is improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a magneto-optical recording medium according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a magneto-optical disk device.

FIG. 3 is a diagram illustrating data erasure.

FIG. 4 is a diagram illustrating data writing.

FIG. 5 is a diagram for explaining a single mask reproducing method;
(A) is a plan view, and (B) is a longitudinal sectional view of a recording medium.

6A and 6B are diagrams illustrating a data reproducing method according to the embodiment, wherein FIG. 6A is a plan view and FIG. 6B is a longitudinal sectional view of a recording medium.

FIG. 7 is a diagram for explaining a reproduction principle of a conventional example.

[Explanation of symbols]

 Reference Signs List 14 transparent substrate 16 dielectric layer 18 'reproducing layer 20' control layer 22 recording layer 24 protective film 58 beam spot 60 up spin mask 62 opening 68 up spin mask

Claims (4)

[Claims] 1. A magneto-optical recording medium comprising a multilayer magnetic film containing a rare earth metal and a transition metal as main components, comprising: a reproducing layer having an easy axis of magnetization perpendicular to a film surface; A control layer which exhibits an easy axis of magnetization in the in-plane direction at room temperature, in which the magnetic moment of the rare earth is dominant, and which contains at least Gd as the rare earth metal and Fe as the transition metal and has no compensation temperature; and A recording layer having an easy axis of magnetization perpendicular to the film surface provided thereon, wherein the Curie temperatures of the reproducing layer, the control layer, and the recording layer are Tc1, Tc2, and Tc3, respectively, and the reproduction at room temperature is performed. When the coercive forces of the layer and the recording layer are Hc1 and Hc3, respectively, the Curie temperature of each magnetic layer satisfies the relationship of Tc1> Tc2 Tc3> Tc2, and the reproducing layer and the recording layer are kept at room temperature. Force, a magneto-optical recording medium satisfy the relationship of Hc3> Hc1. 2. The magneto-optical recording medium according to claim 1, wherein the composition of the reproducing layer is mainly composed of GdFeCo. 3. The magneto-optical recording medium according to claim 1, wherein the composition of the control layer contains GdFe as a main component. 4. The magneto-optical recording medium according to claim 1, wherein the control layer contains 0 to 60 at% of a non-magnetic material selected from the group consisting of Si, Al and Ti.