JPH113548A - Magneto-optical recording medium and reproducing, recording and erasing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain satisfactory reproducing performance when a short wavelength beam such as of a blue light emitting laser is used. SOLUTION: On a circular substrate, a laminated film consisting of Pt and Co or consisting of Pd and Co is formed as a reproduction layer 3, and on this layer, a film attaining the Curie point when radiated with a beam for reproduction is formed as a reproduction switching layer 5, although it is a perpendicular magnetized film in the normal temperature, then the vertical magnetized film is formed thereon as a memory layer 7. Also the perpendicular magnetized film is formed between the reproduction layer 3 and the reproduction switching layer 5 as a joint layer.

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 and a method of reproducing, recording and erasing the same, and more particularly to a magneto-optical recording medium which is recorded and reproduced by a short-wavelength beam such as a blue light emitting laser, and its reproducing, recording and erasing methods. It relates to an erasing method.

[0002]

2. Description of the Related Art Usually, in a magneto-optical disk using a magneto-optical film as a memory layer, when information is recorded, a beam is irradiated on the magneto-optical disk to heat the magneto-optical layer at a spot portion and to record information such as external magnetization. Recording is performed by changing the magnetization direction of the magneto-optical layer due to the influence. Recently, opportunities for recording or reproducing a large amount of information such as image information have been increasing. Under such circumstances, there is an increasing demand for recording more information on an optical recording medium or reproducing the information accurately. Various approaches have been taken to meet that demand.

First, in a disk, there is a method of reducing the track pitch in order to increase the recording density in the radial direction. For this purpose, it is necessary to reduce the recording mark width. Until now, the standard track pitch was 1.6 μm, but recently attempts have been made to reduce the track pitch, and 1.4 μm, 1.2 μm, and even 1.0 μm have been reported.

Next, in order to increase the recording density in the circumferential direction, it is necessary to reduce the length of a recording mark. In order to reduce the width and length of the recording mark, a considerably small mark can be formed by using only the high energy region near the center of the recording beam. This is called the pen record.

However, the problem lies in reproduction. Reproduction is performed by optically detecting a mark in the beam spot. Therefore, it is always necessary to basically have only one mark in the beam spot. if,
This is because if a plurality of marks exist in the beam spot, information will be mixed and necessary information cannot be correctly reproduced. Such mixing of information in the beam spot is called intersymbol interference (FIG. 5).

That is, unless intersymbol interference is suppressed,
It is impossible to retrieve and reproduce only the information represented by the mark in a part of the beam spot. The beam spot diameter is, for example, a wavelength 68 widely used at present.
In the case of a red light emitting laser of 0 mm, the limit is to limit the diameter to about 1.0 μm even in an ideal optical system. For this reason,
In the radial direction, if the track pitch is smaller than about 1.0 μm in principle, marks recorded on adjacent tracks are reproduced at the same time.

Further, the mark length and the mark interval are 1.0 μm.
If it is much smaller than m, the previous and next marks will be reproduced simultaneously. However, a recording / reproducing method and a medium capable of accurately reproducing information recorded at a considerably high density have been invented. This is called magnetic super-resolution. The basic idea of this method is as follows.

The temperature of the recording medium rises due to the irradiation of the reproducing beam. Since the beam intensity is higher at the center, the center of the beam is heated. However, since the medium is moving with respect to the beam, the rear side in the reproduction beam spot becomes relatively hot due to the heat generation effect. If a part of the beam spot is masked using this characteristic of the temperature distribution and only the unmasked part is reproduced, only the information of a small part in the spot can be reproduced.

In other words, this is substantially equivalent to reducing the reproduction beam spot size. That is, information recorded at a considerably high density can be accurately reproduced. The principle of mask generation is based on magnetic super-resolution (MSR: Magnetically Induced) using a change in magnetization direction due to a change in magnetic coupling force.
ed Super Resolution) Reproduction is proposed, and in addition, a change due to a change in transmittance due to a phase change is also announced.

[0010] Magnetic super-resolution includes FAD, RAD, CA
D, double mask, etc. For example, FIG.
In the conventional CAD system shown in FIG. 1, the memory layer 7 is masked by the in-plane magnetization region 3D of the reproduction layer 3 during reproduction.

As a result, the perpendicular magnetization region 3A of the reproducing layer 3
The marks 7A and 7C of the memory layer 7 are transferred to the memory. Then, high-density reproduction is performed by reproducing only the magnetization transferred to the perpendicular magnetization region 3A in the beam-irradiated spot 10 as recording information.

In the conventional FAD system shown in FIG. 11, at the time of reproduction, the memory layer 7 is masked by the demagnetized region 5B which has reached the Curie point of the reproduction switching layer 5.
Thereby, the perpendicular magnetization region 5A of the reproduction switching layer 5
The mark 7A of the memory layer 7 is transferred to the reproduction layer 3 via the. Then, high-density reproduction is performed by reproducing only the magnetization transferred to the aperture region 3A in the spot 10 irradiated with the beam as recording information.

Further, in the conventional double mask method, a low-temperature region and a high-temperature region are masked in a portion irradiated with a beam. Then, high-density reproduction is performed by reproducing only the region of the portion interposed therebetween (for example, Japanese Patent Application Laid-Open No. 4-255946).

However, information is recorded at a higher density,
There is a demand for reliable reproduction of the information.
Therefore, it is conceivable to shorten the wavelength of the beam. It is known that how small the beam can be narrowed depends on the wavelength of the beam. The shorter the wavelength, the smaller the beam spot diameter can be.

[0015]

However, when information recorded on a conventionally used magneto-optical recording medium is reproduced with a short-wavelength beam, there is a problem that the C / N value of the reproduced signal does not reach a sufficient level. is there. This is because the material used for the reproducing layer of the conventional magneto-optical recording medium is a magnetic material mainly composed of a heavy rare earth metal-transition metal alloy such as GdFeCo. This is due to the small car rotation angle.

Therefore, a small Kerr rotation angle means that a change in the polarization angle of the reflected beam is small.
As a result, there is a problem that the signal component of the magneto-optical reproduction signal is reduced. The present invention solves the above problems, when using a short-wavelength beam such as a blue light emitting laser for high-density recording and reproduction, a magneto-optical recording medium that can obtain good reproduction characteristics and its reproduction, recording and It is intended to provide an erasing method.

[0017]

In order to achieve the above object, a magneto-optical recording medium according to claim 1 of the present invention comprises:
A magneto-optical recording medium having at least three magnetic layers of a reproducing layer, a reproducing switching layer, and a memory layer on a substrate, wherein the reproducing layer determines a Kerr rotation angle of a reflected beam reflecting an irradiated beam. The memory layer is made of a magnetic film in which information is recorded according to the direction of perpendicular magnetization.
It is formed of a magnetic film formed between the reproducing layer and the memory layer and transferring the magnetization of the memory layer in a part of the region heated by the irradiated beam to the reproducing layer. Therefore, even when a short-wavelength beam such as a blue light emitting laser is used during reproduction, a laminated film of Pt and Co or Pd
A sufficient Kerr rotation angle can be obtained by the reproducing layer composed of the laminated film of Co and Co.

According to a second aspect of the present invention, in the magneto-optical recording medium of the first aspect, the reproducing switching layer is in-plane magnetized at room temperature, and changes from in-plane magnetization to perpendicular magnetization at a predetermined temperature. It consists of a changing film. Therefore, the memory layer is masked by the magnetization disappearance region that has reached the Curie point of the reproduction switching layer, and the magnetization direction of the memory layer is transferred to the reproduction layer via the perpendicular magnetization region of the reproduction switching layer, and within the beam spot, Only the magnetization transferred to a certain reproducing layer is read as recorded information.

According to a third aspect of the present invention, in the magneto-optical recording medium of the second aspect, the perpendicular magnetic recording medium is formed between the reproducing switching layer and the memory layer and has a Curie temperature lower than the Curie temperature of the reproducing switching layer. It has a cutting layer that is a magnetic film. A magneto-optical recording medium according to a fourth aspect of the present invention is the magneto-optical recording medium according to the third aspect, wherein the intermediate layer, the recording layer, the switching layer, and the initialization layer mainly composed of a rare earth metal and a transition metal are formed on the memory layer. At least 4
A magnetic layer. Therefore, the memory layer is masked by the demagnetized region that has reached the Curie point of the cutting layer, and the cut layer is masked by the in-plane magnetization region of the reproduction switching layer and the demagnetized region that has reached the Curie point. The magnetization direction of the memory layer is transferred to the reproduction layer via the perpendicular magnetization region of the reproduction switching layer, and only the magnetization transferred to the reproduction layer within the beam spot is read out as recording information.

A magneto-optical recording medium according to a fifth aspect of the present invention is the magneto-optical recording medium according to the first to fourth aspects, further comprising a bonding layer formed between a reproducing layer and a reproducing switching layer and being a perpendicular magnetization film. It is. Therefore, the magnetization direction of the memory layer transferred via the perpendicular magnetization region of the reproduction switching layer is transferred to the reproduction layer via the bonding layer. In a magneto-optical recording medium according to a sixth aspect of the present invention, in the magneto-optical recording medium according to the fifth aspect, the bonding layer is formed of a perpendicular magnetization film having a Curie temperature lower than the Curie temperature of the reproduction switching layer. Things. Therefore, the reproduction switching layer is masked by the demagnetized region that has reached the Curie point of the bonding layer, and the magnetization direction of the memory layer is transferred to the reproduction layer via the reproduction switching layer and the perpendicular magnetization region of the bonding layer. Only the magnetization transferred to the reproducing layer in the spot is read as recorded information.

According to a seventh aspect of the present invention, in the magneto-optical recording medium of the first to sixth aspects, the reproducing layer is made of an alloy film mainly composed of a light rare earth metal and a transition metal, or a light rare earth metal. And a layer mainly composed of a transition metal. The magneto-optical recording medium according to claim 8 is the magneto-optical recording medium according to claims 1 to 6, wherein the reproducing layer is an alloy film containing light rare earth metal, heavy rare earth metal, and transition metal as main components, or light rare earth element. A layer composed mainly of a metal, a heavy rare earth metal and a transition metal, or a layer mainly composed of an alloy of the light rare earth metal, the heavy rare earth metal and the transition metal, and a layer composed of two layers. is there.

The magneto-optical recording medium according to the ninth aspect is the magneto-optical recording medium according to the seventh or eighth aspect, wherein Nd or Sm is used as the light rare earth metal and Co is used as the transition metal. Therefore, even when a short-wavelength beam such as a blue light emitting laser is used during reproduction, an alloy magnetic film or a laminated film of a light rare earth metal and a transition metal, or an alloy of a light rare earth metal, a heavy rare earth metal, and a transition metal A sufficient Kerr rotation angle can be obtained by the reproducing layer made of a magnetic film or a laminated film. A magneto-optical recording medium according to a tenth aspect is the magneto-optical recording medium according to the first to seventh aspects, wherein the magneto-optical recording medium is formed between the substrate and the reproducing layer, and is formed of ZnS or ZnS and SiO _2.
And a protective film made of a mixture of the above. Pt / C
Since o and Pb / Co do not react with S in ZnS, ZnS or the like having a high refractive index can be used.

According to another aspect of the present invention, there is provided a method for reproducing a magneto-optical recording medium, comprising: a substrate having at least three magnetic layers of a reproducing layer, a reproducing switching layer, and a memory layer. A laminated film of Pt and Co or a laminated film of Pd and Co for rotating the polarization angle of the reflected beam in different directions according to the direction of its magnetization, and the memory layer is a magnetic layer in which information is recorded according to the direction of perpendicular magnetization. The reproducing switching layer is a method for reproducing a magneto-optical recording medium comprising a magnetic film formed between the reproducing layer and the memory layer. In regions where the temperature rise is relatively small, the magnetization is changed from in-plane magnetization to the perpendicular magnetization state. The by the magnetization of the memory layer of a partial region within the heated region is transferred to the reproducing layer by the beam, in which so as to reproduce.

According to a twelfth aspect of the present invention, there is provided a reproducing method for a magneto-optical recording medium, wherein a portion of a reproduction switching layer, whose temperature is increased, is changed from in-plane magnetization to a perpendicular magnetization state by irradiating a beam. In this case, the magnetization of the memory layer in a part of the region heated by the method is transferred to the reproducing layer and reproduced. In the reproducing method of a magneto-optical recording medium according to the thirteenth aspect, of the portions where the temperature of the reproducing switching layer and the cutting layer is increased by irradiating the beam, the reproducing switching layer is exposed in a relatively small area. Change from internal magnetization to perpendicular magnetization, and
The cutting layer maintains the perpendicular magnetization state, and in a region where the temperature rise is relatively moderate, the reproduction switching layer is in the perpendicular magnetization state, and the cutting layer is in the perpendicular magnetization state and in a region where the temperature rise is relatively large. The magnetization of the memory layer in a part of the region heated by the irradiated beam is transferred to the reproducing layer for reproduction by erasing the magnetization of the cutting layer.

According to a fourteenth aspect of the present invention, in the method of reproducing a magneto-optical recording medium according to the eleventh to thirteenth aspects, the linear velocity of a portion to be reproduced is set for the entire surface of the medium or for each of a plurality of regions. It is intended to be constant. According to a fifteenth aspect of the present invention, there is provided a method of reproducing a magneto-optical recording medium according to the eleventh to fourteenth aspects, wherein reproduction is performed using a beam having a wavelength of 550 nm or less.

[0026] According to another aspect of the present invention, there is provided a recording method for a magneto-optical recording medium, wherein at least three magnetic layers of a reproducing layer, a reproducing switching layer, and a memory layer are provided on the substrate. A laminated film of Pt and Co or a laminated film of Pd and Co for rotating the polarization angle of the reflected beam in different directions according to the direction of its magnetization, and the memory layer is a magnetic layer in which information is recorded according to the direction of perpendicular magnetization. A readout switching layer is a recording method for a magneto-optical recording medium comprising a magnetic film formed between a readout layer and a memory layer, and performs recording by using a beam having a wavelength longer than that of a beam used during reproduction. It is something to do.

[0027] According to a twelfth aspect of the present invention, there is provided a method for erasing a magneto-optical recording medium, wherein at least three magnetic layers of a reproducing layer, a reproducing switching layer, and a memory layer are provided on the substrate. A laminated film of Pt and Co or a laminated film of Pd and Co for rotating the polarization angle of the reflected beam in different directions according to the direction of its magnetization, and the memory layer is a magnetic layer in which information is recorded according to the direction of perpendicular magnetization. The reproducing switching layer is a method for erasing a magneto-optical recording medium comprising a magnetic film formed between the reproducing layer and the memory layer, and erasing using a beam having a wavelength longer than the wavelength of the beam used during reproduction. It is something to do.

[0028]

Next, the present invention will be described with reference to the drawings. FIGS. 1A and 1B are explanatory views showing a magneto-optical disk according to a first embodiment of the present invention, in which FIG. 1A is a cut surface along a recording track being reproduced, and FIG. It is a perspective view when it sees from.

Here, the read / write switching layer is formed by using an in-plane magnetized film which is in an in-plane magnetization state at room temperature, becomes high temperature by irradiation of a read beam, becomes a perpendicular magnetization state, and further loses magnetization in a high temperature portion. The method will be described as an example. In FIG. 1A, a substrate 1 is a circular substrate made of a transparent material having tracking irregularities formed in a spiral shape.

A silicon nitride film or the like having a thickness of about 70 nm is formed as a lower protective layer 2 on the substrate 1. Further, on the lower protective layer 2, as the reproducing layer 3, a laminated film (multilayer) made of Pt and Co, or P
A laminated film made of d and Co is formed with a thickness of about 15 nm. In this case, as the reproducing layer 3, for example, a film thickness of 0.5
A layer in which a Pt (or Pd) nm layer and a Co layer having a thickness of 1 nm are alternately and repeatedly stacked for 10 periods is used, but the present invention is not limited to this structure.

On top of this, a reproduction switching layer 5
Gd, which is in-plane magnetized at room temperature, becomes high temperature by irradiation of the reproducing beam, becomes perpendicularly magnetized, and disappears in the high temperature portion.
An in-plane magnetized film of Fe or the like is formed with a thickness of about 50 nm. Further thereon, as a memory layer 7, TbFeCo is used.
Is formed with a thickness of about 50 nm, and finally a SiN film or the like is formed as an upper protective film 8 with a thickness of about 70 nm.

Next, a reproducing operation will be described as an operation according to the first embodiment of the present invention with reference to FIG.
Each layer is heated by the irradiation of the reproduction beam, but since the disk is moving, a high-temperature region exists behind the spot 10 irradiated with the beam, that is, at a position shifted in the disk moving direction.

In the reproduction switching layer 5, the perpendicular magnetization regions 5A and 5C are regions where the magnetization changes from the in-plane direction to the vertical direction by heating, and the magnetization disappearance region 5B is a region where the temperature has further increased and the magnetization has disappeared. The other unheated region 5D remains in the in-plane magnetization state.

Here, Pt and Co (or Pd and Co)
The reproduction layer 3 composed of the laminated film of the above has a small coercive force, and the magnetization direction changes in the direction of the magnetic field when a relatively weak magnetic field is applied by itself. Therefore, the magnetization recorded in the memory layer 7,
Here, the mark 7A is transferred to the aperture region 3A of the reproduction layer 3 via the perpendicular magnetization region 5A of the reproduction switching layer 5.

The transfer of the mark 7D recorded in the memory layer 7 in the spot 10 to the reproduction layer 3 is prevented by the in-plane magnetization region 5D of the reproduction switching layer 5. Further, since the magnetization has disappeared in the magnetization disappearing region 5B of the reproduction switching layer 5, the magnetization recorded in the memory layer 7, here the mark 7B, is not transferred to the reproduction layer 3.

Therefore, regions 3D and 3B of reproduction layer 3 masked by in-plane magnetization region 5D and magnetization disappearance region 5B of reproduction switching layer 5 are magnetized in the same direction as the reproduction magnetic field, that is, in the direction opposite to the recording magnetic field. You. On the other hand, in the perpendicular magnetization region 5C of the reproduction switching layer 5, similarly to the perpendicular magnetization region 5A, the magnetization recorded in the memory layer 7, here the mark 7C, is transferred to the reproduction layer 3.

However, since the area 3C to be transferred is already outside the spot 10, it is not irradiated with the reproduction beam and becomes out of the read target. Thereby, Pt and Co
The mark 7A is transferred only to the aperture region 3A of the reproducing layer 3 made of a laminated film of (or Pd and Co) and read by the reproducing beam.

Accordingly, a large Kerr rotation angle can be obtained even when reproduction is performed using a short-wavelength beam such as a blue light emitting laser as a reproduction beam. Also, as compared with the case where a material such as GdFeCo is used for the reproducing layer as in the related art, even when reproducing a single mark, C / N
Practically sufficiently good reproduction characteristics can be obtained without deterioration of characteristics such as ratio.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is an explanatory diagram showing a magneto-optical disk according to a second embodiment of the present invention.
(A) is a cut surface along the recording track being reproduced, (b)
FIG. 3 is a perspective view of a recording track being reproduced when viewed from above. In the figure, the same or equivalent parts as those described above (see FIG. 1) are denoted by the same reference numerals.

Here, the read / write switching layer is formed by using an in-plane magnetized film which is in an in-plane magnetization state at room temperature, becomes high temperature by irradiation with a read beam, becomes a perpendicular magnetization state, and loses magnetization in a high temperature portion. The method will be described as an example. When reproducing a magneto-optical disk using magnetic super-resolution, the reproducing layer 3 and the reproducing switching layer 5 are formed by exchange coupling force.
It is necessary to surely make the magnetic connection.

In general, the laminated film of Pt and Co (or Pd and Co) used for the reproducing layer 3 has a weak exchange coupling force with the reproducing switching layer 5, and the magnetization direction at the boundary between the regions of the reproducing switching layer 5 is small. Changes tend not to be clearly transcribed. Here, as compared with the first embodiment, the regeneration switching layer 5 and the bonding layer 4 having exchange coupling force are compared.
Is formed between the reproducing layer 3 and the reproducing switching layer 5.

The bonding layer 4 is made of Gd having a thickness of about 15 nm.
A perpendicular magnetization film such as FeCo is used. Therefore,
The boundary between the in-plane magnetization region 5D or the magnetization disappearance region 5B of the reproduction switching layer 5 and the perpendicular magnetization region 5A can be clearly transferred to the reproduction layer 3. Therefore, in order to reproduce with a short wavelength beam such as a blue light emitting laser as a reproduction beam,
Even when a laminated film of Pt and Co (or Pd and Co) is used as the reproduction layer 3, noise during reproduction is reduced and good reproduction characteristics can be obtained.

At the time of the reproducing operation, only the mark 7A of the memory layer 7 corresponds to the perpendicular magnetization region 5 of the reproducing switching layer 5.
A, the image is transferred to the aperture region 3A of the reproduction layer 3 via the region 4A of the bonding layer 4. In other areas,
As in the first embodiment (see FIG. 1), the in-plane magnetization region 5D and the magnetization disappearance region 5 of the reproduction switching layer 5 are provided.
B masks the transfer of the magnetization of the memory layer 7.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 3 is an explanatory view showing a magneto-optical disk according to a third embodiment of the present invention.
(A) is a cut surface along the recording track being reproduced, (b)
FIG. 3 is a perspective view of a recording track being reproduced when viewed from above. In the figure, the same or equivalent parts as those described above (see FIG. 2) are denoted by the same reference numerals.

Here, as compared with the above-described second embodiment, the reproduction switching layer 5 has an in-plane magnetization state at room temperature and becomes high temperature by irradiation with the reproduction beam to be in a perpendicular magnetization state. A reproduction method using an in-plane magnetization film that does not lose magnetization will be described as an example. In this case, as the reproduction switching layer 5, an in-plane magnetization film such as GdFe, which is in an in-plane magnetization state at room temperature and is vertically magnetized at a high temperature by irradiation of the reproduction beam, is formed with a thickness of about 50 nm.

However, as the reproducing switching layer 5, a layer having a Curie point at a temperature higher than the temperature at which the reproducing switching layer 5 changes from the in-plane magnetization state to the perpendicular magnetization state is used. In addition, as the reproducing layer 3 and the memory layer 7, those having a Curie point at a temperature higher than the Curie point of the reproducing switching layer 5 are used. When the reproducing beam is applied, the perpendicular magnetization region 5A in the reproducing switching layer 5
In, the magnetization direction changes from the in-plane direction to the vertical direction due to heating, and the other region 5D remains in the perpendicular magnetization state.

Therefore, the magnetization recorded in the memory layer 7, here the mark 7A, is applied to the reproduction layer 3 via the perpendicular magnetization region 5A of the reproduction switching layer 5 and the region 4A of the bonding layer 4.
Is transferred to the aperture region 3A. On the other hand, the mark 7D recorded in the memory layer 7 in the spot 10 is prevented from being transferred to the reproduction layer 3 by the in-plane magnetization region 5D of the reproduction switching layer 5.

Therefore, the region 3D of the reproduction layer 3 masked by the in-plane magnetization region 5D of the reproduction switching layer 5
Are magnetized in the same direction as the reproducing magnetic field, that is, in the direction opposite to the recording magnetic field. The mark 7B recorded on the memory layer 7 is also transferred to the reproduction layer 3 in the same manner. However, since the area 3B to be transferred is already outside the spot 10, the reproduction beam is not irradiated and the mark 3B is not read. Becomes

As a result, Pt and Co (or Pd and C
o) Aperture region 3A of reproduction layer 3 composed of a laminated film
The mark 7A is transcribed and read by the reproduction beam. Therefore, as the reproduction switching layer 5, even when an in-plane magnetization film that does not lose magnetization is used, although it is in an in-plane magnetization state at room temperature and becomes a perpendicular magnetization state when irradiated with a reproduction beam, it becomes high in temperature. Even when reproduction is performed using a short-wavelength beam such as a blue light emitting laser, a large Kerr rotation angle can be obtained.

Further, as in the conventional case, GdF
Compared to the case where a material such as eCo is used, even when reproducing a single mark, characteristics such as C / N ratio are not degraded, and reproduction characteristics sufficiently good for practical use are obtained. Also,
By forming the bonding layer 4 between the reproduction layer 3 and the reproduction switching layer 5, Pt and Co (or Pd and C) having a weak exchange coupling force with the reproduction switching layer 5 as the reproduction layer 3 are formed.
Even in the case of using the laminated film of o), in the reproducing layer 3, the boundary between the in-plane magnetization region 5D or the magnetization disappearance region 5B of the reproduction switching layer 5 and the perpendicular magnetization region 5A can be clarified, and noise during reproduction can be reduced. As a result, good reproduction characteristics can be obtained.

Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 4 is an explanatory view showing a magneto-optical disk according to a fourth embodiment of the present invention.
(A) is a cut surface along the recording track being reproduced, (b)
FIG. 3 is a perspective view of a recording track being reproduced when viewed from above. In the figure, the same or equivalent parts as those described above (see FIG. 2) are denoted by the same reference numerals.

Here, as compared with the above-described second embodiment, the case where the read switching layer 5 and the memory layer 7 are normally in a perpendicular magnetization state and are heated at a high temperature by the irradiation of the read beam. The following describes an example of a reproducing method in which a cutting layer 6 in which the magnetization is lost is provided. In this case, a perpendicular magnetization film (about 30 nm in thickness) such as TbFe having a Curie point at a temperature lower than the Curie point of the reproduction switching layer 5 is formed as the cutting layer 6 between the reproduction switching layer 5 and the memory layer 7. Have been.

When the reproducing beam is irradiated, in the reproducing switching layer 5, in the perpendicular magnetization regions 5A and 5C, the magnetization direction changes from the in-plane direction to the vertical direction due to heating. In the cutting layer 6, since the Curie temperature is lower than the Curie temperature of the reproduction switching layer 5, a relatively large demagnetized region 6B is generated.

Therefore, the demagnetized region 6B of the cutting layer 6
Accordingly, the magnetization recorded in the memory layer 7, here, the mark 7 </ b> B is not transferred to the reproduction layer 3. Also, only the magnetization recorded in the memory layer 7, here the mark 7A, is transferred to the aperture region 3A of the reproduction layer 3 via the perpendicular magnetization region 5A of the reproduction switching layer 5 and the region 4A of the bonding layer 4.

On the other hand, transfer of the mark 7D recorded in the memory layer 7 in the spot 10 to the reproduction layer 3 is prevented by the in-plane magnetization region 5D of the reproduction switching layer 5. The mark 7B recorded on the memory layer 7 is transferred to the reproduction layer 3 in the same manner.

However, since the area 3B to be transferred is already outside the spot 10, the reproduction beam is not irradiated and is not a target to be read. Thereby, Pt and Co
The mark 7A is transferred only to the aperture region 3A of the reproducing layer 3 made of a laminated film of (or Pd and Co) and read by the reproducing beam.

Therefore, even when the cutting layer 6 which is normally in a perpendicular magnetization state and is in a magnetization disappearing state when heated at a high temperature by irradiation of a reproduction beam is provided between the reproduction switching layer 5 and the memory layer 7. Also, a large Kerr rotation angle can be obtained even when reproduction is performed with a short-wavelength beam such as a blue light emitting laser as a reproduction beam. Also, as compared with the case where a material such as GdFeCo is used for the reproducing layer as in the related art, even when reproducing a single mark, C
Practically sufficiently good reproduction characteristics can be obtained without deterioration of characteristics such as / N ratio.

By forming the bonding layer 4 between the reproducing layer 3 and the reproducing switching layer 5, Pt and Co having a weak exchange coupling force with the reproducing switching layer 5 as the reproducing layer 3 are formed.
(Or Pd and Co), the in-plane magnetization region 5 of the reproducing switching layer 5 in the reproducing layer 3.
The boundary between D and the magnetization disappearance region 5B and the perpendicular magnetization region 5A can be clarified, and noise during reproduction can be reduced to obtain good reproduction characteristics.

Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 5 is an explanatory view showing a magneto-optical disk according to a fifth embodiment of the present invention.
(A) is a cut surface along the recording track being reproduced, (b)
FIG. 3 is a perspective view of a recording track being reproduced when viewed from above. In the figure, the same or equivalent parts as those described above (see FIG. 4) are denoted by the same reference numerals.

Here, as compared with the above-described fourth embodiment, a general configuration for enabling the light modulation direct overwrite method is added. That is, an intermediate layer 11, a recording layer 12, a switching layer 13, and an initialization layer 14, each of which is made of a magnetic film mainly composed of a rare earth metal and a transition metal, are sequentially formed on the memory layer 7 and the upper layer protection layer. The layer 8 is formed.

Thus, even in the case of an optical modulation direct overwrite optical disk, a large Kerr rotation angle can be obtained even when reproduction is performed using a short-wavelength beam such as a blue light emitting laser as a reproduction beam. Also, as compared with the case where a material such as GdFeCo is used for the reproducing layer as in the related art, even when reproducing a single mark, the C / C
Practically sufficiently good reproduction characteristics can be obtained without deterioration of characteristics such as N ratio.

Further, by forming the bonding layer 4 between the reproducing layer 3 and the reproducing switching layer 5, Pt and Co having a weak exchange coupling force with the reproducing switching layer 5 as the reproducing layer 3 are formed.
(Or Pd and Co), the in-plane magnetization region 5 of the reproducing switching layer 5 in the reproducing layer 3.
The boundary between D and the magnetization disappearance region 5B and the perpendicular magnetization region 5A can be clarified, and noise during reproduction can be reduced to obtain good reproduction characteristics.

Next, a sixth embodiment of the present invention will be described with reference to FIG. FIG. 6 is an explanatory diagram showing a magneto-optical disk according to a sixth embodiment of the present invention.
(A) is a cut surface along the recording track being reproduced, (b)
FIG. 3 is a perspective view of a recording track being reproduced when viewed from above. In the figure, the same or equivalent parts as those described above (see FIG. 2) are denoted by the same reference numerals.

Here, as compared with the second embodiment, the bonding layer 4 is used as a layer for cutting off the magnetization. That is, by using a perpendicular magnetization film having a Curie point lower than the Curie point of the reproduction switching layer 5 as the bonding layer 4, the same operation as the cutting layer 6 in the above-described fourth embodiment (FIG. 4) is performed. 4 can be obtained.

In this case, the layer is provided not on the memory layer 7 side than the reproduction switching layer 5 like the cutting layer 6, but on the reproduction layer 3 side from the reproduction switching layer 5. Also in this case, the same operation as the initial operation of the cutting layer 6 is obtained, in which a relatively large demagnetized region 4B is obtained. Thus, it is not necessary to separately form the cutting layer 6, and the process of forming the magneto-optical disk can be simplified.

In the first to seventh embodiments described above, as the reproducing layer 3, a laminated film of Pt and Co,
Alternatively, the case where a stacked film of Pd and Co is used has been described as an example. However, the present invention is not limited to this.
Alternatively, a magnetic film made of an alloy of a light rare earth metal and a transition metal may be used.

In this case, as the reproducing layer 3, specifically,
Magnetic films such as NdFeCo and SmFeCo and alloys such as NdCo and SmCo can be given. Even when reproduction is performed using a short-wavelength beam such as a blue light emitting laser as a reproduction beam, a large Kerr rotation angle can be obtained.

A magnetic film made of an alloy of a light rare earth metal and a transition metal tends to have unstable perpendicular magnetization as it is, and it is conceivable that the perpendicular magnetization does not occur depending on the forming method. Regarding this, as the reproducing layer 3, the above-mentioned Pt
Similarly to the laminated film of Co and Co (or Pd and Co), a laminated film of a light rare earth metal and a transition metal may be used.

For example, a stable perpendicular magnetization state can be obtained by repeatedly laminating an Nd layer having a thickness of 0.5 nm and a Co layer having a thickness of 1 nm alternately for ten periods. Further, by using an alloy containing a heavy rare earth metal in a light rare earth metal and a transition metal, or a laminated film of these, a stable perpendicular magnetization state can be obtained.

In the first to seventh embodiments described above, the case where the lower protective layer 2 provided between the substrate 1 and the reproducing layer 3 is formed from a silicon nitride film has been described. Alternatively, the lower protective layer 2 may be formed of a ZnS film or a film made of a mixture of ZnS and SiO ₂ . Generally, when a laminated film of Pt and Co (or Pd and Co) is used as the reproducing layer 3, the conventional GdFe
Compared to the case where a magneto-optical film made of an alloy of a rare earth metal such as Co and Fe is used, the magnetic material is less likely to be oxidized because of its lower reactivity with S and O.

Therefore, by forming the lower protective layer 2 provided between the substrate 1 and the reproducing layer 3 from a film made of ZnS having a high refractive index or a mixture of ZnS and SiO ₂ , the Pt is formed as the reproducing layer 3. In the case where a laminated film of Pd and Co (or Pd and Co) is used, a large amount of reflected light can be obtained, and good reproduction characteristics can be obtained.

[0072]

Next, an embodiment of the present invention will be described with reference to the drawings. First, a method of forming an optical disc according to the first to seventh embodiments will be described. When forming a magneto-optical disk according to the first embodiment (see FIG. 1), a circular substrate 1 formed by a 2P method or the like is
A lower protective film 2 of about 70 nm made of SiN is formed by RF magnetron sputtering. Here, sputtering is performed by using a Si target, introducing a mixed gas of Ar and N ₂ , and setting the gas pressure in the chamber to 5 × 10 −3 Torr.

On this, as the reproducing layer 3, a laminated film made of Pt and Co is formed to a thickness of about 15 nm. Here, Pt,
Using each of Co targets, Ar gas is introduced, the gas pressure in the chamber is set to 5 × 10 −3 Torr, and co-sputtering is performed by controlling the number of rotations and adjusting the lamination cycle. The layer of Pt and Co formed at this time has a configuration in which Pt is 0.5 nm and Co has a lamination period of about 10 cycles of 1 nm, but is not limited to this configuration.

On top of this, a reproduction switching layer 5
A magneto-optical film made of GdFe which shows in-plane magnetization at room temperature
0 nm is formed. Here, it is formed by performing co-sputtering using respective targets of Gd and Fe, introducing Ar gas, and setting the gas pressure in the chamber to 5 × 10 −3 Torr. The composition of GdFe formed at this time is as follows:
(Gd: 29 atm%, Fe: 71 atm%) and about 110
It is perpendicularly magnetized at ゜ C and reaches the Curie point at about 220 ° C, but is not limited to this composition.

Note that due to the characteristics of the present invention, the Curie point of the reproducing switching layer 5 needs to be higher than the temperature at which the reproducing switching layer 5 changes from the in-plane magnetization state to the perpendicular magnetization state by a certain temperature or more. . On top of this, the memory layer 7
A perpendicularly magnetized magneto-optical film made of TbFeCo or the like is formed to a thickness of about 50 nm. Here, cosputtering is performed by using each target of Tb, Fe, and Co, introducing an Ar gas, and setting the gas pressure in the chamber to 5 × 10 −3 Torr.

The composition of TbFeCo formed at this time is (Tb: 21 atm%, Fe: 63.2 atm%, Co: 1
5.8 atm%). Further, an upper protective film 8 of about 70 nm made of SiN is formed thereon by RF magnetron sputtering. The formation conditions are the same as those for the lower protective film 2.

Next, a case of forming a magneto-optical disk according to the second embodiment (see FIG. 2) will be described. In the second embodiment, a light exhibiting perpendicular magnetization made of GdFeCo is used as the bonding layer 4 between the reproducing layer 3 and the reproducing switching layer 5 of the magneto-optical disk according to the first embodiment (see FIG. 1). The magnetic film has a thickness of about 15 nm.

In this case, the target is formed by performing co-sputtering by using respective targets of Gd, Fe, and Co, introducing Ar gas, and setting the gas pressure in the chamber to 5 × 10 −3 Torr. The composition of GdFeCo formed at this time is (Gd: 25 atm%, Fe: 60 atm%, Co: 15 atm%).
atm%), but is not limited to this composition.

The method of forming the magneto-optical disk according to the third embodiment (see FIG. 3) is the same as that of the second embodiment. In this case, in the third embodiment, a perpendicular magnetization film that reaches the Curie point at a temperature higher than the temperature at which the reproduction switching layer 5 enters the perpendicular magnetization state is used.

The method of forming the magneto-optical disk according to the sixth embodiment (see FIG. 6) is the same as that of the second embodiment. In this case, in the sixth embodiment, a perpendicular magnetization film that reaches the Curie point at a temperature lower than the Curie point of the reproduction switching layer 5 is used as the bonding layer 4.

Next, a case of forming a magneto-optical disk according to the fourth embodiment (see FIG. 4) will be described. Here, the targets of Tb and Fe are used, and A
The gas pressure in the chamber was 5 × 10 −3 by introducing r gas.
It is formed by performing co-sputtering as Torr. The composition of TbFe formed at this time is (Tb: 21 atm%,
Fe: 79 atm%), but is not limited to this composition.

In this case, as the reproducing switching layer 5, a magneto-optical film made of GdFe and exhibiting in-plane magnetization at room temperature and having a thickness of about 30 nm is formed. Here, it is formed by performing co-sputtering using respective targets of Gd and Fe, introducing Ar gas, and setting the gas pressure in the chamber to 5 × 10 −3 Torr.

The composition of GdFe formed at this time is as follows:
(Gd: 29 atm%, Fe: 71 atm%) and about 70 ° C.
Perpendicular magnetization. In this case, the cutting layer 6
Is set to, for example, about 140 ° C., and the Curie temperature of the reproduction switching layer 5, for example, about 2 ° C.
The temperature is set lower than 30 ° C.

Next, the case of forming a magneto-optical disk according to the fifth embodiment (see FIG. 5) will be described. Fifth
In the fourth embodiment, between the memory layer 7 and the upper protective layer 8 of the magneto-optical disk according to the fourth embodiment (see FIG. 4),
A general configuration for enabling the direct overwrite method is added. The composition and film thickness of each layer are as shown in FIG. 7, and the formation method is almost the same as described above.

In the first to sixth embodiments described above, as the reproducing layer 3, a laminated film of Pt and Co,
Alternatively, the case where a stacked film of Pd and Co is used has been described as an example. However, a magnetic film made of an alloy of a light rare earth metal and a transition metal may be used as the reproducing layer 3 instead. Hereinafter, a method of forming a magnetic layer made of an alloy of NdGdFe as the reproducing layer 3 will be described by way of example.

In this case, as the reproducing layer 3, NdGdCo
A magneto-optical film having a perpendicular magnetization of about 15 nm is formed. Here, using a target of each of Nd, Gd, and Co, co-sputtering is performed by introducing an Ar gas and setting the gas pressure in the chamber to 5 × 10 −3 Torr. The composition of NdGdCo formed at this time is as follows:
(Nd: 5 atm%, Gd: 25 atm%, Co: 55 atm%), but is not limited to this composition.

[0087]

As described above, according to the first aspect of the present invention,
Is a magneto-optical recording medium having at least three magnetic layers of a reproducing layer, a reproducing switching layer, and a memory layer on a substrate, wherein the reproducing layer is a reflected beam that reflects an irradiated beam. A Pt and Co laminated film or a Pd and Co laminated film is used to rotate the polarization angle of Pt and Co in different directions depending on the direction of its magnetization, and the memory layer uses a magnetic film on which information is recorded according to the direction of perpendicular magnetization. The reproduction switching layer uses a magnetic film that is formed between the reproduction layer and the memory layer and transfers the magnetization of the memory layer in a part of the region heated by the irradiated beam to the reproduction layer. is there. Therefore, as in the conventional case, GdF
Compared to the case where a magneto-optical film made of an alloy of a heavy rare earth metal such as eCo and a transition metal is used, even when a short-wavelength beam such as a blue light emitting laser is used during reproduction, Pt
A sufficient Kerr rotation angle can be obtained by a reproducing layer composed of a laminated film of Pd and Co or a laminated film of
Even in the case of short marks having low characteristics such as the N ratio, good reproduction characteristics can be obtained.

The magneto-optical recording medium according to claim 2 is the magneto-optical recording medium according to claim 1, wherein the reproduction switching layer is in-plane magnetized at room temperature, and changes from in-plane magnetization to perpendicular magnetization at a predetermined temperature. It consists of a changing film. A magneto-optical recording medium according to a third aspect of the present invention is the magneto-optical recording medium according to the second aspect, wherein the perpendicular magnetic film is formed between the reproducing switching layer and the memory layer and has a Curie temperature lower than the Curie temperature of the reproducing switching layer. It has a certain cutting layer.

The magneto-optical recording medium according to claim 4 is the magneto-optical recording medium according to claim 3, wherein an intermediate layer mainly composed of a rare earth metal and a transition metal, a recording layer, a switching layer, and an initial layer are formed on the memory layer. And at least four magnetic layers. Therefore, in a magneto-optical recording medium of various reproduction systems using magnetic super-resolution, even when a short-wavelength beam such as a blue light emitting laser is used during reproduction, a laminated film of Pt and Co or a film of Pd and Co A sufficient Kerr rotation angle can be obtained by the reproducing layer made of the laminated film, and good reproducing characteristics can be obtained even in the case of a short mark having a relatively low characteristic such as C / N ratio.

A magneto-optical recording medium according to a fifth aspect of the present invention is the magneto-optical recording medium according to the first to fourth aspects, further comprising a bonding layer formed between the reproducing layer and the reproducing switching layer and being a perpendicular magnetization film. It is. Accordingly, the magnetization direction of the memory layer transferred via the perpendicular magnetization region of the reproduction switching layer is transferred to the reproduction layer via the bonding layer, and the exchange layer has a relatively weak exchange coupling force with the reproduction switching layer. However, the boundary between the in-plane magnetization region or demagnetization region of the reproduction switching layer and the perpendicular magnetization region can be clearly transferred to the reproduction layer, and Pt and Co or Pd and Co is laminated as the reproduction layer. Even when a film is used, noise during reproduction can be reduced and good reproduction characteristics can be obtained.

The magneto-optical recording medium according to claim 6 is the magneto-optical recording medium according to claim 5, wherein the junction layer is a film whose Curie temperature is a perpendicular magnetization film and lower than the Curie temperature of the reproduction switching layer. It consists of. Therefore, reproduction by magnetic super-resolution can be performed at a relatively low temperature as in the case where the cutting layer is provided on the memory layer side from the reproduction switching layer without separately forming the cutting layer. Can be simplified.

A magneto-optical recording medium according to claim 7 is the magneto-optical recording medium according to claims 1 to 6, wherein the reproducing layer is formed of an alloy film containing a light rare earth metal and a transition metal as a main component, or a light rare earth metal. And a layer mainly composed of a transition metal. The magneto-optical recording medium according to claim 8 is the magneto-optical recording medium according to claims 1 to 6, wherein the reproducing layer is an alloy film containing light rare earth metal, heavy rare earth metal, and transition metal as main components, or light rare earth element. A layer composed mainly of a metal, a heavy rare earth metal and a transition metal, or a layer mainly composed of an alloy of the light rare earth metal, the heavy rare earth metal and the transition metal, and a layer composed of two layers. is there.

The magneto-optical recording medium of claim 9 is the magneto-optical recording medium of claim 7 or 8, wherein Nd or Sm is used as the light rare earth metal and Co is used as the transition metal. Therefore, even when a short-wavelength beam such as a blue light emitting laser is used during reproduction, the reproduction layer composed of a magnetic film or a laminated film of these metal alloys enables
Sufficient Kerr rotation angle can be obtained, and good reproduction characteristics can be obtained even for short marks having relatively low characteristics such as C / N ratio.

A magneto-optical recording medium according to a tenth aspect of the present invention is the magneto-optical recording medium according to the first to sixth aspects, wherein the protective film is formed between the substrate and the reproducing layer and is made of ZnS or a mixture of ZnS and SiO _2. It is provided with. Therefore, a larger amount of reflected light can be obtained by the enhancement effect.

In the method for reproducing a magneto-optical recording medium according to the eleventh aspect, in a region where the temperature of the reproducing switching layer rises by irradiating a beam, a region where the temperature rise is relatively small is changed from in-plane magnetization to perpendicular magnetization. By changing the state, the magnetization disappears in the region where the temperature rise is relatively large and exceeds the Curie temperature, so that the magnetization of the memory layer in a part of the region heated by the irradiated beam is transferred to the reproduction layer Let's play it. Claim 1
The method of reproducing the magneto-optical recording medium of No. 2 is to change the temperature-raised portion of the reproducing switching layer from in-plane magnetization to perpendicular magnetization by irradiating the beam, and thereby to change the temperature in the region heated by the irradiated beam. The reproduction is performed by transferring the magnetization of the memory layer in a part of the region to the reproduction layer.

In the method of reproducing a magneto-optical recording medium according to the thirteenth aspect, in the region where the temperature rise of the reproduction switching layer and the cutting layer by irradiation with a beam is relatively small, the reproduction switching is performed. The layer is changed from the in-plane magnetization to the perpendicular magnetization state, and the cutting layer maintains the perpendicular magnetization state, and in a region where the temperature rise is relatively moderate,
The reproduction switching layer maintains the perpendicular magnetization state, the magnetization of the cutting layer disappears, and the magnetization of the cutting layer disappears in a region where the temperature rise is relatively large, so that the region is heated by the irradiated beam. The reproduction is performed by transferring the magnetization of the memory layer in a part of the region to the reproduction layer.

According to a fourteenth aspect of the present invention, there is provided a method for reproducing a magneto-optical recording medium according to the eleventh to thirteenth aspects, wherein the linear velocity of a portion to be reproduced is changed over the entire surface of the medium or for each of a plurality of regions. It is intended to be constant. According to a fifteenth aspect of the present invention, there is provided a method of reproducing a magneto-optical recording medium according to the eleventh to fourteenth aspects, wherein reproduction is performed using a beam having a wavelength of 550 nm or less. Therefore, even when a short wavelength laser such as a blue light emitting laser is used, high-density reproduction can be realized.

The recording method for a magneto-optical recording medium according to claim 16 has at least three magnetic layers of a reproducing layer, a reproducing switching layer, and a memory layer on a substrate, and the reproducing layer receives an irradiated beam. A laminated film of Pt and Co or a laminated film of Pd and Co for rotating the plane of polarization of the reflected beam in different directions depending on the direction of its magnetization, and the memory layer is a magnetic layer in which information is recorded in the direction of perpendicular magnetization. A readout switching layer is a recording method for a magneto-optical recording medium comprising a magnetic film formed between a readout layer and a memory layer, and performs recording by using a beam having a wavelength longer than that of a beam used during reproduction. It is something to do.

According to a seventeenth aspect of the present invention, there is provided a recording method for a magneto-optical recording medium having at least three magnetic layers of a reproducing layer, a reproducing switching layer, and a memory layer on a substrate. A laminated film of Pt and Co or a laminated film of Pd and Co for rotating the plane of polarization of the reflected beam in different directions depending on the direction of its magnetization, and the memory layer is a magnetic layer in which information is recorded in the direction of perpendicular magnetization. The reproducing switching layer is a method for erasing a magneto-optical recording medium comprising a magnetic film formed between the reproducing layer and the memory layer, and erasing using a beam having a wavelength longer than the wavelength of the beam used during reproduction. It is something to do. Therefore, it is possible to use an inexpensive and high-power red-emitting laser for recording and erasing.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a magneto-optical disk according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a magneto-optical disk according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a magneto-optical disk according to a third embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a magneto-optical disk according to a fourth embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a magneto-optical disk according to a fifth embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a magneto-optical disk according to a sixth embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a composition example of a magneto-optical disk according to a fifth embodiment of the present invention.

FIG. 8 is an explanatory view showing a conventional magneto-optical disk.

FIG. 9 is an explanatory view showing another conventional magneto-optical disk.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Lower protective film, 3 ... Reproduction layer, 4 ... Bonding layer,
5: reproduction switching layer, 6: cutting layer, 7: memory layer,
8 Upper protective layer.

Claims (17)

[Claims] 1. A magneto-optical recording medium having at least three magnetic layers, a reproducing layer, a reproducing switching layer, and a memory layer, on a substrate, wherein the reproducing layer has a curved mirror for reflecting an irradiated beam. The memory layer is made of a magnetic film on which information is recorded according to the direction of perpendicular magnetization, and is made of a laminated film of Pt and Co or a laminated film of Pd and Co for rotating the rotation angle in different directions depending on the direction of magnetization. The reproduction switching layer is formed between the reproduction layer and the memory layer, and includes a magnetic film that transfers the magnetization of the memory layer in a part of the region heated by the irradiated beam to the reproduction layer. Magneto-optical recording medium. 2. The magneto-optical recording medium according to claim 1, wherein the reproduction switching layer is in-plane magnetized at room temperature, and changes from in-plane magnetization to perpendicular magnetization at a predetermined temperature. recoding media. 3. The magneto-optical recording medium according to claim 2, further comprising a cutting layer formed between the reproducing switching layer and the memory layer, the cutting layer being a perpendicular magnetization film having a Curie temperature lower than the Curie temperature of the reproducing switching layer. Characteristic magneto-optical recording medium. 4. The magneto-optical recording medium according to claim 3, wherein at least four magnetic layers of an intermediate layer mainly composed of a rare earth metal and a transition metal, a recording layer, a switching layer, and an initialization layer are formed on the memory layer. A magneto-optical recording medium comprising: 5. The magneto-optical recording medium according to claim 1, further comprising a bonding layer formed between a reproducing layer and a reproducing switching layer and being a perpendicular magnetization film. 6. The magneto-optical recording medium according to claim 5, wherein the Curie temperature of the bonding layer is a perpendicular magnetization film and lower than the Curie temperature of the reproduction switching layer. 7. The magneto-optical recording medium according to claim 1, wherein the reproducing layer is an alloy film containing light rare earth metal and a transition metal as main components, or a light rare earth metal and a transition metal as main components. 1. A magneto-optical recording medium, comprising: 8. The magneto-optical recording medium according to claim 1, wherein the reproducing layer is an alloy film containing light rare earth metal, heavy rare earth metal, and transition metal as main components, or a light rare earth metal, heavy rare earth metal, A magneto-optical recording medium comprising a laminated film in which each of transition metals or a layer mainly composed of an alloy of the light rare earth metal, heavy rare earth metal and transition metal is laminated. . 9. The magneto-optical recording medium according to claim 7, wherein the light rare earth metal is Nd or Sm, and the transition metal is Co.
A magneto-optical recording medium, characterized in that: 10. The magneto-optical recording medium according to claim 1, further comprising a protective layer formed between the substrate and the reproducing layer and made of ZnS or a mixture of ZnS and SiO _2. Medium. 11. A substrate having at least three magnetic layers of a reproducing layer, a reproducing switching layer, and a memory layer on a substrate, wherein the reproducing layer determines the Kerr rotation angle of a beam reflected by an irradiated beam, P to rotate in different directions depending on the direction
The memory layer is made of a magnetic film in which information is recorded according to the direction of perpendicular magnetization, and the reproducing switching layer is formed between the reproducing layer and the memory layer. A method for reproducing a magneto-optical recording medium consisting of a magnetic film, in which the temperature rises in the reproduction switching layer by irradiating a beam, and the region where the temperature rise is relatively small changes from in-plane magnetization to perpendicular magnetization. In a region where the temperature rise is relatively large and the Curie temperature is exceeded, magnetization is lost, so that the magnetization of the memory layer in a part of the region heated by the irradiated beam is transferred to the reproduction layer for reproduction. A method for reproducing a magneto-optical recording medium. 12. A substrate having at least three magnetic layers of a reproducing layer, a reproducing switching layer and a memory layer on a substrate, wherein the reproducing layer determines the Kerr rotation angle of a beam reflected by an irradiated beam, P to rotate in different directions depending on the direction
The memory layer is made of a magnetic film in which information is recorded according to the direction of perpendicular magnetization, and the reproducing switching layer is formed between the reproducing layer and the memory layer. A method for reproducing a magneto-optical recording medium comprising a magnetic film, wherein a beam is irradiated to change a temperature-raised portion of a reproducing switching layer from in-plane magnetization to a perpendicular magnetization state, thereby being heated by the irradiated beam. A method for reproducing the magneto-optical recording medium, wherein the reproduction is performed by transferring the magnetization of the memory layer in a part of the region to the reproduction layer. 13. On a substrate, there are at least four magnetic layers of a reproducing layer, a cutting layer, a reproducing switching layer, and a memory layer, and the reproducing layer adjusts a Kerr rotation angle of a beam reflected by an irradiated beam. The memory layer is composed of a magnetic film on which information is recorded according to the direction of perpendicular magnetization, and the reproducing switching layer is composed of a laminated film of Pt and Co or a laminated film of Pd and Co rotated in different directions depending on the direction of magnetization. A magnetic layer formed between the layer and the memory layer, and the cutting layer is formed between the reproduction switching layer and the memory layer or between the reproduction layer and the reproduction switching layer, and has a Curie temperature lower than the Curie temperature of the reproduction switching layer. A method for reproducing a magneto-optical recording medium comprising a perpendicularly magnetized film, comprising: irradiating a beam; In a region where the temperature rise is relatively small, the reproduction switching layer is changed from in-plane magnetization to a perpendicular magnetization state, and the cutting layer maintains the perpendicular magnetization state. The layer maintains the perpendicular magnetization state, and the cutting layer loses the magnetization, so that the magnetization of the memory layer in a part of the area heated by the irradiated beam is transferred to the reproduction layer for reproduction. A method for reproducing a magneto-optical recording medium, comprising: 14. A magneto-optical recording method according to claim 11, wherein a linear velocity of a portion to be reproduced is constant over the entire surface of the medium or a plurality of regions. Media playback method. 15. The reproducing method for a magneto-optical recording medium according to claim 11, wherein the reproducing is performed using a beam having a wavelength of 550 nm or less. 16. A substrate having at least three magnetic layers of a reproducing layer, a reproducing switching layer, and a memory layer on a substrate, wherein the reproducing layer determines the Kerr rotation angle of a beam reflected by an irradiated beam and the magnetization of the beam. P to rotate in different directions depending on the direction
The memory layer is made of a magnetic film in which information is recorded according to the direction of perpendicular magnetization, and the reproducing switching layer is formed between the reproducing layer and the memory layer. A recording method for a magneto-optical recording medium comprising a magnetic film, wherein recording is performed using a beam having a longer wavelength than a beam used for reproduction. 17. A semiconductor device having at least three magnetic layers, a reproducing layer, a reproducing switching layer, and a memory layer, on a substrate, wherein the reproducing layer determines the Kerr rotation angle of a beam reflected by an irradiated beam, P to rotate in different directions depending on the direction
The memory layer is made of a magnetic film in which information is recorded according to the direction of perpendicular magnetization, and the reproducing switching layer is formed between the reproducing layer and the memory layer. A method for erasing a magneto-optical recording medium comprising a magnetic film, wherein the erasing is performed using a beam having a longer wavelength than a beam used for reproduction.