JP2000268426A - Magnet-optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a magneto-optical recording medium in which each domain of a recording layer can be accurately transferred to a reproducing layer and the transferred magnetic domains can be detected even when the recording density is increased. SOLUTION: This magneto-optical recording medium 10 consists of a light- transmitting substrate 1, base layer 2, reproducing layer 3, nonmagnetic layer 4, recording layer 5 and protective layer 6. The recording layer 5 consists of a first magnetic layer 51 which is an in-plane magnetization film at room temp. and changes into a perpendicular magnetization film at a specified temp. or higher and a second magnetic layer 52 which is the perpendicular magnetization film. The reproducing layer 3 is the in-plane magnetization film at room temp. and changes into the perpendicular magnetization film at a specified temp. or higher. Only the magnetic domains at a specified temp. or higher in the first magnetic layer 51 exchange and couple with the magnetic domains in the second magnetic layer 52 and are transferred by magnetostatic coupling through the nonmagnetic layer 4 to the reproducing layer 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical recording medium for recording and / or reproducing signals.

[0002]

2. Description of the Related Art Magneto-optical recording media have attracted attention as rewritable, large-capacity, and highly reliable recording media, and have begun to be put to practical use as computer memories and the like. Recently, the recording capacity is 6.0 Gby.
tes's magneto-optical recording medium is AS-MO (Advanced)
d Storage Magneto Optical
(Disc) standard and is about to be put to practical use. Reproduction of a signal from such a high-density magneto-optical recording medium is performed by irradiating a laser beam so that magnetic domains of the recording layer of the magneto-optical recording medium are transferred to the reproducing layer and only the transferred magnetic domains can be detected. Forming a detection window in the reproduction layer,
MSR for detecting magnetic domains transferred from the formed detection window
(Magnetically Induced Sup
er Resolution) method.

Further, a magnetic domain enlarging / reproducing technique for reproducing an signal by applying an alternating magnetic field in reproducing a signal from a magneto-optical recording medium and enlarging and transferring a magnetic domain of a recording layer to a reproducing layer by a laser beam and the alternating magnetic field has also been developed. Thus, a magneto-optical recording medium capable of recording and / or reproducing a signal of 14 Gbytes by using this technology has been proposed.

[0004]

However, as the recording density increases, a plurality of magnetic domains are transferred to the reproducing layer when the magnetic domains of the recording layer are transferred to the reproducing layer by irradiating a laser beam.
There has been a problem that signal reproduction cannot be performed accurately. This problem occurs in a magneto-optical recording medium for reproducing signals by the MSR method and a magneto-optical recording medium for reproducing signals by magnetic domain expansion reproduction.

Therefore, the present invention solves such a problem,
It is an object of the present invention to provide a magneto-optical recording medium capable of accurately transferring each magnetic domain of a recording layer to a reproducing layer even when the recording density increases, and detecting the transferred magnetic domain.

[0006]

The invention according to claim 1 is a magneto-optical recording medium including a reproducing layer, a non-magnetic layer, and a recording layer.

The non-magnetic layer is formed in contact with the reproducing layer, and the recording layer is formed in contact with the non-magnetic layer. The recording layer includes a first magnetic layer that is a perpendicular magnetic film and a second magnetic layer that is an in-plane magnetic film at room temperature and becomes a perpendicular magnetic film at a predetermined temperature or higher.

In the magneto-optical recording medium according to the first aspect, the recording layer comprises a first magnetic layer and a second recording layer. At a predetermined temperature or lower, the first magnetic layer is a perpendicular magnetization film. The second magnetic layer is an in-plane magnetic film. Therefore, the first
The transfer of the magnetic domain to the reproducing layer via the nonmagnetic layer does not occur only by the leakage magnetic field of the magnetic domain of the magnetic layer. When the temperature of the magneto-optical recording medium becomes equal to or higher than a predetermined temperature, a region of the second magnetic layer which is equal to or higher than the predetermined temperature becomes a perpendicular magnetization film and exchange-couples with the magnetic domain of the first magnetic layer. As a result, the domain of the exchange-coupled magnetic domain is equivalent to an increase in the film thickness as a whole, and has a strength sufficient to transfer the leakage magnetic field reaching the reproducing layer through the nonmagnetic layer to the reproducing layer by magnetostatic coupling. Reach. Then, only the exchange-coupled magnetic domains are transferred to the reproducing layer via the nonmagnetic layer.

Therefore, according to the first aspect of the present invention, the recording layer is composed of the first magnetic layer and the second magnetic layer, and even if the conventional recording layer is made thin, it can be selected as the reproducing layer. Magnetic domains can be transferred with good efficiency.

Further, since a nonmagnetic layer is inserted between the reproducing layer and the recording layer, even if the thickness of the reproducing layer is reduced, C
A magneto-optical recording medium having a good / N ratio can be manufactured.

[0011] The invention according to claim 2 is characterized in that the reproducing layer comprises:
This is a magneto-optical recording medium including a non-magnetic layer and a recording layer.

The non-magnetic layer is formed in contact with the reproducing layer, and the recording layer is formed in contact with the non-magnetic layer. The recording layer is a first magnetic layer which is an in-plane magnetized film at room temperature formed in contact with the non-magnetic layer and which becomes a perpendicular magnetic film at a predetermined temperature or higher, and is formed in contact with the first magnetic layer. And a second magnetic layer which is a perpendicular magnetization film.

In the magneto-optical recording medium according to the present invention, the recording layer includes a first magnetic layer and a second magnetic layer, and the first magnetic layer has an in-plane magnetization at a predetermined temperature or higher. The film becomes a perpendicular magnetization film, and maintains in-plane magnetization below a predetermined temperature. The first magnetic layer exists between the second magnetic layer, which is a perpendicular magnetization film, and the nonmagnetic layer.

As a result, a leakage magnetic field from a magnetic domain existing in a region of a predetermined temperature or lower in the second magnetic layer is blocked by the magnetic domain holding the in-plane magnetization of the first magnetic layer and reaches the reproducing layer. However, the magnetic domains existing in the region below the predetermined temperature are not transferred to the reproducing layer. On the other hand, a region of the first magnetic layer having a temperature equal to or higher than a predetermined temperature changes from an in-plane magnetic film to a perpendicular magnetic film, and exchange-couples with a magnetic domain of the second magnetic layer. Therefore, the area of the exchange-coupled magnetic domain is equivalent to an increase in the film thickness as a whole, and the magnetic field reaching the reproducing layer via the non-magnetic layer reaches a strength sufficient to be transferred to the reproducing layer by magnetostatic coupling. . Then, only the exchange-coupled magnetic domains are transferred to the reproducing layer via the nonmagnetic layer.

Therefore, according to the second aspect of the present invention, the recording layer is composed of the first magnetic layer and the second magnetic layer, and the thickness of the conventional recording layer is reduced to the thickness of the second magnetic layer. Even when the thickness is reduced to the film thickness, the magnetic domains of the second magnetic layer can be transferred to the reproducing layer with high selectivity.

Further, since a nonmagnetic layer is inserted between the reproducing layer and the recording layer, even if the thickness of the reproducing layer is reduced, C
A magneto-optical recording medium having a good / N ratio can be manufactured.

Further, the invention according to claim 3 provides a reproducing layer,
This is a magneto-optical recording medium including a non-magnetic layer and a recording layer.

The non-magnetic layer is formed in contact with the reproducing layer, and the recording layer is formed in contact with the non-magnetic layer. The recording layer is a second perpendicular magnetic film formed in contact with the nonmagnetic layer.
And a first magnetic layer for selecting a magnetic domain of the second magnetic layer and transferring it to the reproducing layer.

In the magneto-optical recording medium according to the third aspect, the recording layer is composed of a first magnetic layer and a second magnetic layer, and the first magnetic layer is irradiated with a laser beam to a predetermined level. When the temperature is equal to or higher than the predetermined temperature, the leakage magnetic field from the magnetic domain of the second magnetic layer in contact with the magnetic domain whose temperature is equal to or higher than the predetermined temperature is increased so that the second magnetic layer transferred to the reproducing layer via the nonmagnetic layer is increased. Select a magnetic domain. As a result, only the magnetic domains of the second magnetic layer selected by the first magnetic layer are transferred to the reproducing layer via the non-magnetic layer.

Therefore, according to the third aspect of the present invention, the second magnetic layer selected by the first magnetic layer by forming the recording layer from the first magnetic layer and the second magnetic layer. Only the magnetic domains of the layer can be transferred to the reproducing layer by magnetostatic coupling via the non-magnetic layer.

Since a non-magnetic layer is inserted between the reproducing layer and the recording layer, even if the thickness of the reproducing layer is reduced, C
A magneto-optical recording medium having a good / N ratio can be manufactured.

Further, the invention according to claim 4 is characterized in that a reproducing layer,
This is a magneto-optical recording medium including a non-magnetic layer and a recording layer.

The non-magnetic layer is formed in contact with the reproducing layer, and the recording layer is formed in contact with the non-magnetic layer. The recording layer is a second perpendicular magnetic film formed in contact with the nonmagnetic layer.
And a first magnetic layer which is formed in contact with the second magnetic layer and which is an in-plane magnetic film at room temperature and which becomes a perpendicular magnetic film at a predetermined temperature or higher. Is 50 to 10
The thickness of the second magnetic layer constituting the recording layer is in the range of 100 to 2000 °.

In the magneto-optical recording medium according to the present invention, the recording layer is composed of a second magnetic layer and a first magnetic layer, and the first magnetic layer has an in-plane magnetization film at a predetermined temperature or higher. To a perpendicular magnetization film, and retains in-plane magnetization below a predetermined temperature. Further, since the thickness of the nonmagnetic layer is in the range of 50 to 1000 ° and the thickness of the second recording layer is in the range of 100 to 2000 °, the nonmagnetic layer can be formed only by the leakage magnetic field from the second magnetic layer. Thus, the magnetic domain of the second magnetic layer cannot be transferred to the reproducing layer by magnetostatic coupling.

On the other hand, a region of the first magnetic layer having a temperature higher than a predetermined temperature is changed from an in-plane magnetic film to a perpendicular magnetic film.
Exchange-coupled with the magnetic domain of the magnetic layer. Therefore, the area of the exchange-coupled magnetic domain is equivalent to an increase in the film thickness as a whole, and the magnetic field reaching the reproducing layer via the non-magnetic layer reaches a strength sufficient to be transferred to the reproducing layer by magnetostatic coupling. . Then, only the exchange-coupled magnetic domains are transferred to the reproducing layer via the nonmagnetic layer.

Therefore, according to the fourth aspect of the present invention, the recording layer is composed of the first magnetic layer and the second magnetic layer, and the thickness of the conventional recording layer is reduced to the thickness of the second magnetic layer. Even when the thickness is reduced to the film thickness, the magnetic domains of the second magnetic layer can be transferred to the reproducing layer with high selectivity by the second magnetic layer.

Since a non-magnetic layer is inserted between the reproducing layer and the recording layer, even if the thickness of the reproducing layer is reduced, C
A magneto-optical recording medium having a good / N ratio can be manufactured.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. The sectional structure of the magneto-optical recording medium according to the present invention will be described with reference to FIG. The magneto-optical recording medium 10 includes a light-transmitting substrate 1, a base layer 2, a reproducing layer 3, a non-magnetic layer 4, a recording layer 5, and a protective layer 6. The recording layer 5 is an in-plane magnetic film at room temperature, and includes a first magnetic layer 51 which becomes a perpendicular magnetic film at a predetermined temperature or higher, and a second magnetic layer 52 which becomes a perpendicular magnetic film. The reproducing layer 3 is a magnetic layer that is an in-plane magnetic film at room temperature and becomes a perpendicular magnetic film at a predetermined temperature or higher.

The translucent substrate 1 is made of glass, polycarbonate, or the like, the underlayer 2 is made of SiN,
Is composed of GdFeCo, the nonmagnetic layer 4 is composed of SiN, the first magnetic layer 51 is composed of GdFeCo, the second magnetic layer 52 is composed of TbFeCo, and the protective layer 6 is composed of TbFeCo.
Is made of an ultraviolet curable resin.

The SiN forming the underlayer 2 and the SiN forming the nonmagnetic layer 4 are formed by RF magnetron sputtering, and GdFeC forming the reproducing layer 3 is used.
o, GdFeCo constituting the first magnetic layer 51 and TdFeCo constituting the second magnetic layer 52 are formed by a DC magnetron sputtering method.

The thickness of the underlayer 2 is 400 to 100.
0 °, the thickness of the reproducing layer 3 is 150 to 1000 °, the thickness of the nonmagnetic layer 4 is 50 to 1000 °,
The thickness of the first magnetic layer 51 is 100 to 2000 °, the thickness of the second magnetic layer 52 is 250 to 2500 °, and the thickness of the protective layer 6 is about 10 μm. Also, the first
The total thickness of the recording layer 51 and the second recording layer 52 is substantially equal to the thickness of the recording layer in the conventional magneto-optical recording medium.

Referring to FIGS. 2, 3, and 4, the second magnetic layer 5
The mechanism by which the two magnetic domains are transferred to the reproducing layer 3 will be described. Before irradiating the magneto-optical recording medium 10 with a laser beam, the reproducing layer 3 and the first magnetic layer 51 of the recording layer 5 are formed.
Holds the in-plane magnetization, and the second magnetic layer 52 of the recording layer 5
It has perpendicular magnetization modulated by a recording signal. And
The first magnetic layer 51 retains the in-plane magnetization 510 along the direction of the leakage magnetic field from each magnetic domain of the second magnetic layer 52.

Magneto-optical recording medium 1 having such a magnetization distribution
When the laser beam LB is irradiated on the first magnetic layer 51, the region of the first magnetic layer 51 having a temperature equal to or higher than a predetermined temperature changes from the in-plane magnetic film to the perpendicular magnetic film, and exchange-couples with the magnetic domain 61 of the second magnetic layer 52. And
Magnetic domains 5101 appear in the first magnetic layer 51. And
In the first magnetic layer 51, a region having a temperature equal to or lower than a predetermined temperature retains in-plane magnetizations 5102 and 5103, and the leakage magnetic field from the magnetic domains 62, 63, 64, 65, and 66 of the second magnetic layer 52 is In-plane magnetization 5102, 5103 of first magnetic layer 51
And does not reach the reproducing layer 3 via the nonmagnetic layer 4. Therefore, the magnetic domains 62, 63, 6 of the second magnetic layer 52
4, 65 and 66 are not transferred to the reproducing layer 3 by magnetostatic coupling.

On the other hand, referring to FIG. 4, the second magnetic layer 52
Has the temperature dependence of the magnetization shown by the curve k2, and the first magnetic layer 51 has the temperature dependence of the magnetization shown by the curve k1. Therefore, at the temperature T1 equal to or higher than the transition temperature at which the first magnetic layer 51 changes from the in-plane magnetization film to the perpendicular magnetization film, the second magnetic layer 5
The leakage magnetization from the second magnetic domain 61 is the sum of the magnetization Ms2 of the second magnetic layer 52 and the magnetization Ms1 of the first magnetic layer 51. Accordingly, the magnetic domains 61 and 5101 in the exchange-coupled region become stronger than the leakage magnetic field from the magnetic domains 61 and have sufficient strength to be transferred to the reproducing layer 3 via the nonmagnetic layer 4.
As a result, only the magnetic domains 61 of the second magnetic layer 52 are transferred to the reproducing layer 3 by magnetostatic coupling, and the magnetic domains 30 appear on the reproducing layer 3. Then, the laser light LB undergoes magneto-optical interaction with the magnetic domains 30 to rotate the plane of polarization of the reflected light, and the magnetic domains 30 are detected by detecting the degree of rotation of the plane of polarization.

In the magneto-optical recording medium 10, the temperature at which the first magnetic layer 51 changes from an in-plane magnetic film to a perpendicular magnetic film is 1
The temperature at which the reproducing layer 3 changes from an in-plane magnetic film to a perpendicular magnetic film is 150 ° C. (hereinafter the same).

The significance of the magneto-optical recording medium 10 having the non-magnetic layer 4 between the reproducing layer 3 and the recording layer 5 will be described with reference to FIG. Non-magnetic layer 4 between reproducing layer 3 and recording layer 5
In the magneto-optical recording medium 200 having no layer, the reproducing layer 3
3 must be thicker than the reproducing layer 3 of the magneto-optical recording medium 10. That is, when the magneto-optical recording medium 200 is irradiated with the laser beam LB and the temperature rises to some extent, the magnetic domains 5101 of the first magnetic layer 51 exchange-coupled with the magnetic domains 61 of the second magnetic layer 52 cause the magnetization of the magnetic domains 61 to change. To go in the same direction, a magnetization 5104 is created. Then, since there is no nonmagnetic layer 4 between the reproducing layer 33 and the recording layer 5, a magnetization 331 in the same direction as the magnetization 5104 is generated on the side of the reproducing layer 33 near the recording layer 5. Therefore, when the thickness of the reproducing layer 33 is small, the magnetization 331 is generated over the entire region in the thickness direction of the reproducing layer 33, and the reflected light of the laser beam LB rotates its polarization plane by the magnetization 331. Is detected. As a result, the magnetization 331 in a direction different from the magnetization direction of the magnetic domain 61 is detected, and the C / N ratio of the reproduction signal decreases. In order to prevent the C / N ratio of the reproduction signal from lowering, the thickness of the reproduction layer 33 is increased, and even if the magnetization 331 is transferred to the reproduction layer 33 closer to the recording layer 5, the laser beam L
It is necessary that the in-plane magnetization 332 exists on the B irradiation surface. When the thickness of the reproducing layer 33 is increased, when the magnetization in the same direction as the magnetic domain 61 is transferred over the entire region in the thickness direction of the magnetic domain 330, the magnetic domain 3
30 will be detected. Therefore, in the magneto-optical recording medium 200 in which the reproducing layer 33 is exchange-coupled with the recording layer 5, the thickness of the reproducing layer 33 needs to be set to 800 ° or more.

However, in the magneto-optical recording medium 10 in which the nonmagnetic layer 4 exists between the reproducing layer 3 and the recording layer 5, since the above-mentioned problem does not occur, the reproducing layer 3 Is sufficient in the range of 150 to 800 ° and the non-magnetic layer 4 and the recording layer are different from each other in that a reproduction signal having a good C / N can be obtained even if the thickness of the reproduction layer 3 is reduced. There is significance to insert between 5.

In the magneto-optical recording medium 10, the recording layer 5
Has been described as being composed of a first magnetic layer 51 which is a perpendicular magnetic film at a predetermined temperature or higher and a second magnetic layer 52 which is a perpendicular magnetic film at room temperature or higher. Layer 5
1 and TbFeCo constituting the second magnetic layer 52 are only different from each other in Gd atom and Tb atom. Therefore, the recording layer of the magneto-optical recording medium according to the present invention has Gd in the thickness direction of the magneto-optical recording medium.
The first magnetic layer 5 is controlled by controlling the content of atoms and Tb atoms.
It is assumed that one magnetic layer having the same distribution of Gd atoms and Tb atoms as the recording layer including the first and second magnetic layers 52 is also included.

Further, in the magneto-optical recording medium 10, it has been described that the reproducing layer 3 is a magnetic layer which is an in-plane magnetic film at room temperature and becomes a perpendicular magnetic film at a predetermined temperature or higher.
However, the present invention is not limited to this. Even when a perpendicular magnetization film is used for the reproducing layer 3, each magnetic domain of the second magnetic layer 52 is selected by the first magnetic layer 51 in the same manner as described above, and the nonmagnetic layer 4 is formed by magnetostatic coupling. Can be transferred to the reproduction layer 3 via

The magneto-optical recording medium according to the present invention is not limited to the magneto-optical recording medium 10 shown in FIG. 1, but may be a magneto-optical recording medium 100 shown in FIG. Magneto-optical recording medium 100
A second magnetic layer 52, which is a perpendicular magnetization film formed by contacting the recording layer 5 of the magneto-optical recording medium 10 with the non-magnetic layer 4,
A magneto-optical recording medium in which a first magnetic layer 51, which is an in-plane magnetic film formed at room temperature and is a perpendicular magnetic film at a predetermined temperature or higher and formed in contact with the second magnetic layer 52, is used instead of the recording layer 55. It is.

In the magneto-optical recording medium 100, the thickness of the nonmagnetic layer 4 is set in the range of 50 to 1000 °, and the thickness of the second magnetic layer 52 is set in the range of 250 to 2500 °. As a result, each magnetic domain of the second magnetic layer 52 is not transferred to the reproducing layer 3 by the magnetostatic coupling via the nonmagnetic layer 4 only by the leakage magnetic field from the magnetic domain.

Referring to FIGS. 7 and 8, magneto-optical recording medium 10
The mechanism by which the magnetic domain of the second magnetic layer 52 is transferred to the reproducing layer 3 will be described. Referring to FIG. 7, before the magneto-optical recording medium 100 is irradiated with a laser beam, the reproducing layer 3 and the first magnetic layer 51 of the recording layer 5 maintain in-plane magnetization, and The second magnetic layer 52 has a perpendicular magnetization modulated by a recording signal. Then, the second magnetic layer 5
The first magnetic layer 51 holds the in-plane magnetization 510 along the direction of the leakage magnetic field from each of the magnetic domains 2.

The magneto-optical recording medium 1 having such a magnetization distribution
When the laser beam LB is irradiated at 00, referring to FIG.
In the first magnetic layer 51, a region having a temperature equal to or higher than a predetermined temperature is changed from an in-plane magnetic film to a perpendicular magnetic film, and a magnetic domain 5101 exchange-coupled with the magnetic domain 61 of the second magnetic layer 52 is formed in the first magnetic layer 51. appear. Then, in the first magnetic layer 51, a region having a temperature equal to or lower than a predetermined temperature retains the in-plane magnetizations 5102 and 5103, and thus the magnetic domains 62, 63, 64, 65, of the second magnetic layer 52.
The leakage magnetic field from the magnetic domains 62, 63, 64, 65,
66 does not reach a strength sufficient to transfer to the reproducing layer 3 via the nonmagnetic layer 4 and is not transferred to the reproducing layer 3 by magnetostatic coupling.

On the other hand, the magnetic domains 61 of the second magnetic layer 52 are exchange-coupled with the magnetic domains 5101 of the first magnetic layer 51, and
As described with reference to FIG. 4 above, at a temperature T1 equal to or higher than the transition temperature at which the first magnetic layer 51 changes from an in-plane magnetic film to a perpendicular magnetic film, the magnetic field Ms2 of the second magnetic layer 52 increases.
And the magnetization Ms1 of the first magnetic layer 51. Accordingly, the magnetic domains 61 and 5101 in the exchange-coupled region become stronger than the leakage magnetic field from the magnetic domains 61 and have sufficient strength to be transferred to the reproducing layer 3 via the nonmagnetic layer 4. As a result, only the magnetic domains 61 of the second magnetic layer 52 are transferred to the reproducing layer 3 by magnetostatic coupling, and the magnetic domains 30 appear on the reproducing layer 3. Then, the laser beam LB is generated by the magnetic domain 30 and the magneto-optical effect.
The polarization plane of the reflected light is rotated, and the magnetic domain 30 is detected by detecting the degree of rotation of the polarization plane.

In the magneto-optical recording medium 100 as well, the non-magnetic layer 4 is inserted between the reproducing layer 3 and the recording layer 5 because the non-magnetic layer 4 is inserted as described with reference to FIG. Even if the thickness of the layer 3 is reduced to about 150 to 1000 ° C.
This is because a reproduced signal having a high / N can be obtained.

In the magneto-optical recording medium 100,
Although the recording layer 5 is an in-plane magnetic film at room temperature, and has been described as including a first magnetic layer 51 which becomes a perpendicular magnetic film at a predetermined temperature or higher and a second magnetic layer 52 which becomes a perpendicular magnetic film, GdFeCo constituting the first magnetic layer 51 and the second magnetic layer 52
Is different from TbFeCo only in that Gd atoms and Tb atoms are different from each other. Therefore, the recording layer of the magneto-optical recording medium according to the present invention has Gd atoms in the thickness direction of the magneto-optical recording medium. And the content of Tb atoms is controlled to include one magnetic layer having the same distribution of Gd atoms and Tb atoms as the recording layer composed of the first magnetic layer 51 and the second magnetic layer 52. .

Further, in the magneto-optical recording medium 100,
Although it has been described that the reproducing layer 3 is a magnetic layer which is an in-plane magnetic film at room temperature and becomes a perpendicular magnetic film at a predetermined temperature or higher, the present invention is not limited to this. Similarly to the above, each magnetic domain of the second magnetic layer 52 is
And transfer to the reproducing layer 3 via the non-magnetic layer 4 by magnetostatic coupling.

The magneto-optical recording medium according to the present invention may be a magneto-optical recording medium 110 shown in FIG. The magneto-optical recording medium 110 is different from the magneto-optical recording medium 100 shown in FIG. 6 in that the recording layer 55 includes a first magnetic layer 53 that is a perpendicular magnetic film and a second magnetic layer 52 that is a perpendicular magnetic film. The other components are the same as those of the magneto-optical recording medium 100 shown in FIG.

Referring to FIG. 10, magneto-optical recording medium 110
Is irradiated with the laser beam LB, the second magnetic layer 5
When the temperature of the region of the second magnetic domain 61 rises, the temperature of the region of the magnetic domain 530 of the first magnetic layer 53 exchange-coupled with the magnetic domain 61 also rises, and the leakage magnetic field from the magnetic domain 61 and the magnetic domain 530 increases.
It becomes stronger than the case of only one. As a result, the magnetic domain 61 becomes
The image is transferred to the reproducing layer 3 through the nonmagnetic layer 4 by magnetostatic coupling. The magnetic domains 62, 63, 64, 65 of the second magnetic layer 52,
Reference numeral 66 indicates that the second magnetic layer 52 has a small thickness and the magnetic domains 62 and 6
3, 64, 65, 66, cannot be transferred to the reproducing layer 3 by the magnetostatic coupling via the non-magnetic layer 4, and the magnetic domain 531 exchange-coupled with the magnetic domains 62, 63, 64, 65, 66. , 532, 534, and 535, the magnetic domains 62, 63, 64, and 65 and the magnetic domains 531,
Considering the leakage magnetic field as the sum of 532, 534, and 535, the magnetic field is not strong enough to be transferred to the reproducing layer 3 by the magnetostatic coupling via the nonmagnetic layer 4, so that the magnetic field other than the magnetic domains 61 of the second magnetic layer 52 The magnetic domains are not transferred to the reproducing layer 3. In this case, the second magnetic layer 52 has a Tb content of 22a.
t. % Of TbFeCo, and the first magnetic layer 53
When the content of Tb is 19 at. % TbFeCo.
Therefore, by reducing the content of Tb, a magnetic layer in which the leakage magnetic field increases as the temperature rises can be obtained, and has a function of selecting a magnetic domain to be transferred to the reproducing layer 3.

Therefore, the magnetic domain can be selected and transferred to the reproducing layer 3 even if the recording layer 56 composed of two perpendicular magnetization films is used.

In the magneto-optical recording medium 110,
The first magnetic layer 53 has been described as having a function of selecting a magnetic domain of the second magnetic layer 52 and transferring the magnetic domain to the reproducing layer 3, but the second magnetic layer 52 has a function of selecting a magnetic domain of the first magnetic layer 53. It may be considered as a magnetic layer having a function of transferring the data to the reproducing layer 3.

The reproducing layer 3 of the magneto-optical recording medium 110
Has been described as a magnetic layer which is an in-plane magnetic film at room temperature and becomes a perpendicular magnetic film at a predetermined temperature or higher. However, the present invention is not limited to this, and may be a perpendicular magnetic film.

The magneto-optical recording medium 1 shown in FIGS.
Reference numerals 0, 100, and 110 are also effective in magnetic domain enlargement reproduction in which a laser beam is irradiated, an alternating magnetic field is applied, and the magnetic domains of the recording layers 5, 55, and 56 are transferred to the reproduction layer 3 and enlarged and reproduced. In this case, the intensity of the laser beam applied to the magneto-optical recording media 10 and 100 is 2.0 mW, the intensity of the applied alternating magnetic field is ± 300 Oe, and the frequency is 25 MHz.
It is.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a magnetization state of each layer before the magneto-optical recording medium shown in FIG. 1 is irradiated with a laser beam.

FIG. 3 is a diagram illustrating a mechanism in which magnetic domains of a recording layer of the magneto-optical recording medium shown in FIG. 1 are transferred to a reproducing layer.

FIG. 4 shows the temperature dependence of the magnetization of a first magnetic layer and a second magnetic layer constituting the recording layer of the magneto-optical recording medium shown in FIG. .

FIG. 5 is a diagram illustrating the significance of a non-magnetic layer of the magneto-optical recording medium shown in FIG.

FIG. 6 is another sectional structural view of the magneto-optical recording medium according to the present invention.

FIG. 7 is a diagram showing a magnetization state of each layer before the magneto-optical recording medium shown in FIG. 6 is irradiated with a laser beam.

8 is a diagram illustrating a mechanism in which magnetic domains of a recording layer of the magneto-optical recording medium shown in FIG. 6 are transferred to a reproducing layer.

9 is a diagram showing another example of the recording layer of the magneto-optical recording medium shown in FIG.

10 is a diagram illustrating a mechanism in which magnetic domains of a recording layer of the magneto-optical recording medium shown in FIG. 9 are transferred to a reproducing layer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Translucent substrate 2 ... Underlayer 3 ... Reproducing layer 4 ... Nonmagnetic layer 5, 55, 56 ... Recording layer 6 ... Protective layer 10, 100, 110, 200 ··· Magneto-optical recording media 51 and 53 ··· First magnetic layer 52 ··· Second magnetic layer 30, 61, 62, 63, 64, 65, 66 and 5101
... Magnetic domains 331, 332, 510, 5102, 5103, 510
4 ... magnetization

Claims (4)

[Claims] A non-magnetic layer formed in contact with the reproducing layer; and a recording layer formed in contact with the non-magnetic layer, wherein the recording layer is a perpendicular magnetization film. 1. A magneto-optical recording medium comprising: a first magnetic layer; and a second magnetic layer which is an in-plane magnetic film at room temperature and becomes a perpendicular magnetic film at a predetermined temperature or higher. 2. A recording medium comprising: a reproducing layer; a nonmagnetic layer formed in contact with the reproducing layer; and a recording layer formed in contact with the nonmagnetic layer, wherein the recording layer is in contact with the nonmagnetic layer. A first magnetic layer which is an in-plane magnetic film at room temperature and becomes a perpendicular magnetic film at a predetermined temperature or higher, and a second magnetic film which is a perpendicular magnetic film formed in contact with the first magnetic layer. A magneto-optical recording medium comprising a magnetic layer. 3. A non-magnetic layer, comprising: a reproducing layer; a non-magnetic layer formed in contact with the reproducing layer; and a recording layer formed in contact with the non-magnetic layer. Of a perpendicular magnetization film formed by
1. A magneto-optical recording medium comprising: a magnetic layer of the formula (1); 4. A recording medium comprising: a reproducing layer; a nonmagnetic layer formed in contact with the reproducing layer; and a recording layer formed in contact with the nonmagnetic layer, wherein the recording layer is in contact with the nonmagnetic layer. Of a perpendicular magnetization film formed by
And a first magnetic layer which is formed in contact with the second magnetic layer and which is an in-plane magnetic film at room temperature and which becomes a perpendicular magnetic film at a predetermined temperature or higher. A magneto-optical recording medium, wherein the thickness of the nonmagnetic layer is in the range of 50 to 1000 °, and the thickness of the first magnetic layer is in the range of 100 to 2000 °.