JPH1166651A - Magneto-optical recording medium and its reproducing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable to obtain a reproduced signal indicating a high SN ratio in high density recording performed in a minute magnetic section by expanding, transcribing and reproducing a recorded magnetic section signal of a magneto-optical recording film in a part of a reproduction layer magnetic film laminated in a area in which an auxiliary magnetic film consisting of an anti-ferroelectric material is heated to a Neel temperature by a reproduced light and magnetized always. SOLUTION: A recording magnetic section recorded in a magneto-optical recording film 10 is transcribed on a reproduction layer magnetic film 24, expanded, and reading reproduction is performed by detecting a polarization Kerr rotation angle of a laser beam for reproduction obtained from a transcription recording magnetic section of the expanded reproduction layer magnetic film 24. Then. as it is limited to a recording magnetic section signal magnetic field from the magneto-optical recording layer 10 being infinitely pure, other noise magnetic field is shut out, and an anti-ferroelectric auxiliary magnetic layer 30 is used as a means performing efficient noise shield and cutting off. Thereby, reproduction of a super-minute recording magnetic section signal which earn be recorded but has been hard to reproduced hitherto can be performed.

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 reproducing method therefor, and more particularly to a magnetic recording medium in which a minute recording magnetic domain extremely smaller than a reproducing light spot is enlarged and a C / N ratio is increased.
The present invention relates to a magneto-optical recording medium suitable for high-density recording capable of obtaining a reproduced signal having a high recording density and a reproducing method thereof.

[0002]

2. Description of the Related Art A magneto-optical recording medium and a magnetic hard disk using a laser beam are rewritable recording information, have a large storage capacity, and have high reliability. Has begun. However, an increase in the amount of information and a reduction in the size of the device are progressing at a high speed, and further higher-density recording / reproducing technology is required. In order to record information on a magneto-optical recording medium, a magnetic field modulation method of applying a magnetic field having a polarity corresponding to a recording magnetic domain signal to a heated portion while irradiating the recording medium with a laser beam is used. This method enables overwrite recording and achieves high-density recording, for example, recording with the shortest mark length of 0.15 μm. Further, an optical modulation recording system for recording by irradiating light whose power has been modulated according to a recording signal under a constant applied magnetic field has also been put to practical use.

[0003]

By the way, in high-density recording of a magneto-optical recording medium, it is easy to record a magnetic domain having a fine hardness. For reproduction, the optical reproduction resolution determined by the spot diameter of the reproduction light beam becomes a problem. For example, it is impossible to identify and reproduce a minute mark having a magnetic domain length of 0.15 μm using reproduction light having a spot diameter of 1 μm. As one approach for eliminating the restriction on the reproduction resolution due to the optical spot diameter of the reproduction light, for example, the Journal of Magnetic Society of J
The magnetic super-resolution technique (MSR) as described in apan, Vol. 17 Supplement No. S1, pp. 201 (1993) has been proposed. This utilizes the fact that a temperature distribution is generated in the magnetic film inside the reproduction light spot when the reproduction light is irradiated to the magneto-optical recording medium, and a magnetic mask is generated in the spot, thereby contributing to the reproduction of the signal. In this case, the typical spot diameter is reduced. If this technique is used, the reproduction resolution can be improved without reducing the actual reproduction light spot diameter. However, in this method, since the effective spot diameter is reduced by the magnetic mask, the amount of light that contributes to the reproduction output decreases, and the reproduction C / N decreases accordingly. As a result, it is difficult to obtain a sufficient C / N.

Japanese Patent Application Laid-Open No. 1-143041 has a first magnetic film, a second magnetic film, and a third magnetic film which are magnetically coupled to each other at room temperature. When the Curie temperatures are TC1, TC2 and TC3, TC2> room temperature and TC2 <TC1, TC3, the coercive force HC1 of the first magnetic film is sufficiently small near the Curie temperature TC2 of the second magnetic film, and the third magnetic The coercive force HC3 of the film is the required temperature TP higher than room temperature to TC2.
A reproducing method for a magneto-optical recording medium in which a magneto-optical recording medium that is sufficiently larger than a required magnetic field in a temperature range up to B and which reproduces data by enlarging a recording magnetic domain of a first magnetic film is disclosed. In this method, the magnetic coupling between the first and third magnetic films is interrupted by utilizing the temperature rise of the medium during the irradiation of the reproduction light, and the first magnetic field is applied by the demagnetizing field acting on the recording magnetic domain and the externally applied magnetic field in that state. The domain of the film is enlarged. In this technique, the second magnetic film whose Curie temperature is set lower than the temperature of the read section during reproduction is used.

[0005] The method described above and the use of a magnetic film having such magnetic properties are not objects of the present invention.

Japanese Patent Application Laid-Open No. 6-295479 has a reproducing layer and a recording layer on a substrate, and the reproducing layer shows in-plane magnetization at room temperature. A magneto-optical recording medium that reproduces a magnetic domain of a recording signal by transferring and expanding the magnetic domain of the recording signal from a recording layer to a reproducing layer using a magnetic film that changes to perpendicular magnetization is disclosed. When reproducing the magneto-optical recording medium, a magnetic domain wall of the transfer magnetic domain is generated in the read layer, thereby enlarging the transfer magnetic domain.

Japanese Patent Application Laid-Open No. Hei 8-7350 discloses a magneto-optical recording medium having a reproducing layer and a recording layer on a substrate and capable of reproducing by enlarging the magnetic domain of the recording layer during reproduction. When reproducing the magneto-optical recording medium, an alternating magnetic field is used as a reproducing magnetic field, and a magnetic field in a direction for expanding the magnetic domain and a magnetic field in the opposite direction are alternately applied to cause the magnetic domain to expand and contract in each magnetic domain. I have.

According to the methods described in JP-A-1-143041, JP-A-6-295479, and JP-A-8-7350, when a recording magnetic signal is transferred to a reproducing layer, a leakage magnetic field or the like is generated. Noise other than the magnetic signal for reproduction is transferred at the same time, and the enlarged reproduction signal from the reproduction layer has a large noise. Therefore, there is a problem that the C / N of the enlarged reproduction signal is reduced, which hinders practical use. In order to solve this problem, the present invention is directed to Japanese Patent Application Laid-Open Nos.
SUMMARY OF THE INVENTION An object of the present invention is to provide a method different from the recording / reproducing layer described in JP-A-295479 and JP-A-8-7350, and to solve the problems of the prior art.
To provide a recording / reproducing method showing a high SN ratio in high-density recording in which recording is performed in a minute magnetic domain. Even when a magnetic domain is enlarged at the time of reproduction, a magnetic domain enlarged immediately after reproducing a recording magnetic domain is provided. An object of the present invention is to provide a magneto-optical recording medium that can be securely erased and a method for reproducing the medium.

[0009]

According to the present invention, at least a magneto-optical recording film, a reproducing magnetic film, and an auxiliary magnetic film made of an antiferromagnetic material are used as a laminated film constituting a recording layer of a magneto-optical recording medium. About things. The magneto-optical recording medium of the present invention,
As shown in FIGS. 1A and 1B, a magneto-optical recording film 10 having at least perpendicular magnetization is formed on a substrate 1 or a transparent protective film 3.
And an auxiliary magnetic film 30 made of an antiferromagnetic material having in-plane magnetism or perpendicular magnetization at room temperature, and an auxiliary magnetic film (abbreviated as reproducing layer magnetic film) 24 having in-plane magnetization or perpendicular magnetization at room temperature. It is provided. The material that exhibits in-plane magnetization at room temperature and that is used for the reproducing layer magnetic film 24 must be a magnetic material that is heated by the reproducing light and transitions to perpendicular magnetization when the temperature exceeds the critical temperature Tcr2. At room temperature, the auxiliary magnetic film 30 made of an antiferromagnetic material has an in-plane magnetization antiferromagnetization or a perpendicular magnetization antiferromagnetization at room temperature. It is a material exhibiting a property of performing exchange coupling with magnetization or in-plane magnetization to firmly fix the magnetization direction of the reproducing layer magnetic film 24, and in the portion irradiated with the reproducing laser light, the reproducing layer magnetic film 24 is laminated. A magnetic material is used in which the exchange coupling with the magnetic layer is canceled and the recording magnetic domain signal is magnetically transferred to the reproducing layer magnetic film 24 satisfactorily.

According to the first aspect of the present invention, the auxiliary magnetic film 30 made of an antiferromagnetic material is heated to a Neel temperature or higher by the reproduction light to form a portion of the reproduction layer magnetic film 24 that is laminated on the paramagnetic area. It is characterized in that the recorded magnetic domain signal is transferred, enlarged and reproduced.

The magneto-optical recording medium according to the second embodiment of the present invention comprises at least a magneto-optical recording layer 10, a reproducing layer magnetic film 24,
An auxiliary magnetic layer 128 which is perpendicular magnetization at room temperature but transitions to in-plane magnetization at or above the critical temperature Tcr1, and exhibits anti-ferromagnetism at in-plane magnetization at room temperature and becomes paramagnetic or non-paramagnetic beyond the Neel temperature Tn or blocking temperature Tb. An auxiliary magnetic film 30 that changes to a magnetized state is used. According to the present invention, the reproducing layer magnetic film 24, the antiferromagnetic auxiliary magnetic film 30 having in-plane magnetization at room temperature, the auxiliary magnetic layer 128, and the magneto-optical recording layer 10 are formed from the incident side of the reproducing laser beam of the magneto-optical recording medium. In particular, the reproducing layer magnetic film 24 and the antiferromagnetic auxiliary magnetic film 30 having in-plane magnetization at room temperature are in direct contact with each other and are laminated. Reproducing layer magnetic film 2
4. Materials such as the auxiliary magnetization layer 128 and the perpendicular magnetization antiferromagnetic auxiliary magnetic film 30 include a Neel temperature Tn and a critical temperature Tcr.
1 and the critical temperature Tcr2, Tcr2 ≦ Tn or Tcr2
A material that satisfies the relationship of b <Tcr1 is selected and used.

As a method of reproducing a recording magnetic domain signal of the magneto-optical recording medium of the present invention, first, although the coercive force is smaller than the magnetic field of the magneto-optical recording layer 10 by irradiation of the reproducing light, The auxiliary magnetic layer 128 for increasing the transfer magnetic field strength of the signal is operated, and then the temperature of the reproducing layer magnetic film 24 becomes Tcr2, and reaches a temperature at which transition from in-plane magnetization to perpendicular magnetization is possible. Then, the auxiliary magnetic film 30 made of the antiferromagnetic material exceeds the Neel temperature Tn or the blocking temperature Tb, and becomes paramagnetized. While the strong exchange coupling force in the in-plane magnetization that had been acting on the recording medium was eliminated, the portion of the reproducing layer magnetic film 24 receiving the reproduction laser beam and having a coercive force smaller than the magnetic field of the magneto-optical recording layer 10 was subjected to magneto-optical recording. The recording domain signal of the layer 10 is transferred.
Then, when the auxiliary magnetic layer 128 reaches the stage where the temperature of the auxiliary magnetic layer 128 exceeds the critical temperature Tcr1 and transitions to in-plane magnetization by the irradiation of the reproducing light, the recording magnetic domain magnetic field signal is cut off, and the expansion of the transfer magnetic domain of the reproducing layer magnetic film 24 reaches a peak. Thus, the transfer signal of the recording magnetic domain is reproduced. This method is characterized in that transfer enlarged reproduction of a recording magnetic domain can be performed using a reproduction laser beam having relatively low power.

A third aspect of the present invention is at least a magneto-optical recording layer 10, a reproducing layer magnetic film 24, and an auxiliary magnetic layer 128 which is perpendicular at room temperature but transitions to in-plane magnetization at or above the critical temperature Tcr1. At room temperature, an auxiliary magnetic film 30 is used, which exhibits antiferromagnetism of perpendicular magnetization and transitions to paramagnetism or nonmagnetism exceeding the Neel temperature Tn or blocking temperature Tb. In the present invention, the reproducing layer magnetic film 24, the auxiliary magnetic layer 128, the perpendicular magnetization antiferromagnetic auxiliary magnetic film 30, and the magneto-optical recording layer 10 are arranged in this order from the side of the magneto-optical recording medium where the reproducing laser beam is incident. In particular, the auxiliary magnetization layer 128 and the perpendicular magnetization antiferromagnetic auxiliary magnetic film 30 are stacked in direct contact. Materials such as the reproducing layer magnetic film 24, the auxiliary magnetic layer 128, and the perpendicular magnetization antiferromagnetic auxiliary magnetic film 30 include Tn or Tb ≦ Tcr2 <Tcr1 between the Neel temperature Tn and the critical temperature Tcr1 and the critical temperature Tcr2. Is selected and used. In this method, the auxiliary magnetic film 30 made of an antiferromagnetic material of the magneto-optical recording medium is made paramagnetic by irradiation of the reproducing laser beam to exceed the Neel temperature Tn or the blocking temperature Tb, and then to the antimagnetic layer 128. The strong exchange coupling force in the in-plane magnetization that has been acting during the contact lamination with the auxiliary magnetic film 30 made of a ferromagnetic material is eliminated. Next, the recording magnetic domain signal of the magneto-optical recording layer 10 is transferred to the auxiliary magnetic layer 128 which has been heated by the reproducing laser beam and has reached the critical temperature Tcr1, and is enlarged. Then
After receiving the laser beam for reproduction, the critical temperature Tcr2
S / N by re-transferring and expanding the recording magnetic domain signal of the auxiliary magnetic layer 128 to the portion of the reproducing layer magnetic film 24 having a coercive force smaller than the magnetic field of the auxiliary magnetic layer 28 and the magneto-optical recording layer 10 It is characterized in that only a magnetic domain signal having a high ratio is reproduced. As a material of the reproducing layer magnetic film 24, it is preferable to select a magnetic material suitable for the transferred and expanded recording magnetic domain to be reduced and disappeared with the movement of the reproducing laser beam irradiation position. It is necessary to select and use a magnetic material suitable for transferring and enlarging by overwriting when reproducing.

A fourth aspect of the present invention is at least a magneto-optical recording layer 10, a reproducing layer magnetic film 24, and an auxiliary magnetic layer 128 which has in-plane magnetization at room temperature but transitions to perpendicular magnetization at or above the critical temperature Tcr1. At room temperature, an auxiliary magnetic film 30 is used which exhibits antiferromagnetism of in-plane magnetization and transitions to paramagnetism beyond the Neel temperature Tn or blocking temperature Tb. The present invention comprises a reproducing layer magnetic film 24, an auxiliary magnetic layer 128, an in-plane magnetization antiferromagnetic auxiliary magnetic film 30, and a magneto-optical recording layer 10 in this order from the side of the reproducing laser beam of the magneto-optical recording medium. In particular, the auxiliary magnetic layer 128 and the antiferromagnetic auxiliary magnetic film 30 having in-plane magnetization are stacked in direct contact. Materials such as the reproducing layer magnetic film 24, the auxiliary magnetic layer 128, and the in-plane magnetization antiferromagnetic auxiliary magnetic film 30 include a Neel temperature Tn and a critical temperature Tc.
Tcr2 <Tcr1 ≦ between r1 and critical temperature Tcr2
Materials are selected and used so as to satisfy the relationship of Tn or Tb. Upon receiving the laser beam for reproduction, the reproducing layer magnetic film 24 of the magneto-optical recording medium reaches the critical temperature Tcr2,
8 and a portion of the reproducing layer magnetic film 24 having a coercive force smaller than the magnetic field of the magneto-optical recording layer 10 is formed. Then, the temperature reaches the critical temperature Tcr1 of the auxiliary magnetic layer 28, and a portion having a coercive force smaller than the magnetic field of the magneto-optical recording layer 10 is formed. When the auxiliary magnetic film 30 made of an antiferromagnetic material is irradiated with the reproducing laser beam, the auxiliary magnetic film 30 has a nail temperature Tn or a blocking temperature T
b, near the temperature at which paramagnetization occurs, the magneto-optical recording layer 1
When the recording magnetic domain signal of 0 is transferred to the auxiliary magnetic layer 28 and expanded, it is characterized in that it can be re-transferred to the portion of the reproducing layer magnetic film 24 and expanded and reproduced. Except for the above, it is the same as the third embodiment of the present invention.

A fifth aspect of the present invention is a magneto-optical recording medium having at least a reproducing magnetic film 24 and a recording magnetic film 10 on a substrate 1, wherein the reproducing magnetic film 24 is in-plane by a reproducing laser beam. The process of transitioning from magnetization to perpendicular magnetization and receiving and expanding the recording magnetic domain signal functions to reproduce the recording magnetic domain signal and, after the recording magnetic domain signal is transferred to the reproducing magnetic film 24, A function of alternately and continuously cutting off noise such as a leakage magnetic field to the reproducing magnetic film 24, an external magnetic field, and the recording magnetic domain signal magnetic field, and canceling the interruption of the magnetic field of the recording magnetic domain signal. An auxiliary magnetic film 30 made of an antiferromagnetic material is provided between the recording magnetic film 10 and the reproducing magnetic film 24, and the material of the auxiliary magnetic film 30 has an in-plane magnetization antiferromagnetic material. Specially to use There is.

A sixth aspect of the present invention is a magnetic recording medium having at least a reproducing magnetic film 24, an auxiliary magnetic film 28, and a recording magnetic film 10 on a substrate, and has an in-plane magnetization at room temperature and a critical temperature Tcr2 or higher. Reproduced magnetic film 2 which changes to perpendicular magnetization at temperature
At the critical temperature Tcr1 lower than the critical temperature Tcr2 of No. 4, an auxiliary magnetic film 28 that transitions from in-plane magnetization to perpendicular magnetization is formed between the recording magnetic film 10 and the reproducing magnetic film 24, At a Neel temperature Tn higher than the critical temperature Tcr2 of the reproducing magnetic film 24 between the auxiliary magnetic film 28 and the reproducing magnetic film 24, the antiferromagnetic auxiliary magnetism of the in-plane magnetization that transitions from antiferromagnetic to paramagnetizing The feature is that the film 30 is formed in contact with the reproducing magnetic film 24.

According to a seventh aspect of the present invention, there is provided a magneto-optical recording medium having at least a recording magnetic film and a reproducing magnetic film on a substrate, and reproducing by irradiating the magneto-optical recording medium with reproducing light. It is characterized in that it is a magneto-optical recording medium using a laminated film in which an auxiliary magnetic film made of an antiferromagnetic material is interposed between the film and the reproducing magnetic film.

According to an eighth aspect of the present invention, there is provided a magneto-optical recording medium having at least a recording magnetic film and a reproducing magnetic film on a substrate, and reproducing by irradiating a reproducing light to the magneto-optical recording medium. It is characterized in that it is a magneto-optical recording medium using a laminated film in which an auxiliary magnetic film made of a perpendicular magnetization antiferromagnetic material is interposed between a magnetic film and a reproducing magnetic film.

According to a ninth aspect of the present invention, there is provided a magneto-optical recording medium having at least a recording magnetic film and a reproducing magnetic film on a substrate, and reproducing by irradiating a reproducing light to the magneto-optical recording medium. It is characterized in that it is a magneto-optical recording medium using a laminated film in which an auxiliary magnetic film made of an in-plane magnetization antiferromagnetic material is interposed between a magnetic film and a reproducing magnetic film.

Among the recording magnetic film, the auxiliary magnetic film made of an antiferromagnetic material, and the reproducing magnetic film, at least the auxiliary magnetic film made of an antiferromagnetic material and the reproducing magnetic film are in direct contact and laminated. Is preferably performed.

Further, the auxiliary magnetic film and the reproducing magnetic film made of the above-mentioned antiferromagnetic material include a combination of a perpendicular magnetic magnetic film and a perpendicular magnetic magnetic film, and a combination of an in-plane magnetic magnetic film and an in-plane magnetic magnetic film. It is preferable to be configured with a combination selected from the combinations.

Furthermore, a laminated structure may be formed by interposing a film made of a nonmagnetic material between the recording magnetic film and the auxiliary magnetic film made of an antiferromagnetic material.

Further, a laminated structure of a film made of a magnetic material and a film made of a nonmagnetic material may be interposed between the recording magnetic film and the auxiliary magnetic film made of an antiferromagnetic material. .

Further, the film made of a non-magnetic material is made of a material selected from materials used for a light reflection film, a heat insulating film, a dielectric film, a transparent protective film, a substrate material and the like of a magneto-optical recording medium. Is also good.

According to a tenth aspect of the present invention, in a magneto-optical recording medium comprising at least a recording magnetic film and a reproducing magnetic film on a substrate, and reproducing by irradiating a magneto-optical recording medium with reproducing light, Magnetized film, non-magnetic material film, first auxiliary magnetic film that transitions to perpendicular magnetization at critical temperature or higher at in-plane magnetization at room temperature, non-magnetic material film, auxiliary magnetic film made of antiferromagnetic material, in-plane magnetization at room temperature The magnetic recording medium is characterized in that it has a film layer such as a second auxiliary magnetic film that functions as a reproducing magnetic film that transitions to perpendicular magnetization at a critical temperature or higher, and is stacked in this order.

According to an eleventh aspect of the present invention, there is provided a magneto-optical recording medium having at least a recording magnetic film and a reproducing magnetic film on a substrate, and reproducing by irradiating the magneto-optical recording medium with reproducing light. Magnetized film, non-magnetic material film, first auxiliary magnetic film which transitions to perpendicular magnetization at critical temperature or higher at in-plane magnetization at room temperature, non-magnetic material film, auxiliary magnetic film made of anti-ferromagnetic material with in-plane magnetization, room temperature Is characterized in that it has a film layer such as a second auxiliary magnetic film functioning as a reproducing magnetic film that transitions to perpendicular magnetization at a critical temperature or higher by in-plane magnetization, and is a magneto-optical recording medium laminated in this order. is there.

According to a twelfth aspect of the present invention, there is provided a magneto-optical recording medium having at least a recording magnetic film and a reproducing magnetic film on a substrate, and reproducing by irradiating the magneto-optical recording medium with reproducing light. Magnetized film, non-magnetic material film, auxiliary magnetic film which changes to perpendicular magnetization at critical temperature or higher due to in-plane magnetization at room temperature,
It is characterized in that it is provided with a film layer such as a nonmagnetic material film, an auxiliary magnetic film made of a perpendicularly magnetized antiferromagnetic material, a perpendicularly magnetized reproducing magnetic film, and the like, and is a magneto-optical recording medium laminated in this order.

According to a thirteenth aspect of the present invention, there is provided a magneto-optical recording medium having at least a recording magnetic film and a reproducing magnetic film on a substrate, and reproducing by irradiating a reproducing light to the magneto-optical recording medium. A magnetic film, a non-magnetic film, an auxiliary magnetic film which is perpendicularly magnetized at room temperature and transitions to an in-plane magnetization at a temperature higher than the critical temperature, an auxiliary magnetic film made of an antiferromagnetic material, and a reproducing magnetic film are provided. It is characterized in that it is a magneto-optical recording medium having a laminated structure.

According to a fourteenth aspect of the present invention, there is provided a magneto-optical recording medium comprising at least a recording magnetic film and a reproducing magnetic film on a substrate, and reproducing by irradiating the magneto-optical recording medium with reproducing light. A magnetic film, an auxiliary magnetic film made of an antiferromagnetic material with in-plane magnetization, a film layer such as a reproducing magnetic film that transitions to perpendicular magnetization at a temperature above a critical temperature due to in-plane magnetization at room temperature, and is laminated in this order. It is characterized by being a magneto-optical recording medium.

According to a fifteenth aspect of the present invention, there is provided a magneto-optical recording medium having at least a recording magnetic film and a reproducing magnetic film on a substrate, and reproducing by irradiating the magneto-optical recording medium with reproducing light. Magnetized film, auxiliary magnetic film made of antiferromagnetic material with in-plane magnetization, first auxiliary magnetic film that transitions to perpendicular magnetization at room temperature above critical temperature due to in-plane magnetization, perpendicular at room temperature above critical temperature due to in-plane magnetization at room temperature A film layer such as a second auxiliary magnetic film that functions as a reproducing magnetic film that changes to magnetization,
It is characterized by a magneto-optical recording medium laminated in this order.

According to a sixteenth aspect of the present invention, there is provided a magneto-optical recording medium having at least a recording magnetic film and a reproducing magnetic film on a substrate, and reproducing by irradiating the magneto-optical recording medium with reproducing light. In addition to a film layer such as a magnetized film, an auxiliary magnetic film made of an antiferromagnetic material having in-plane magnetization, an auxiliary magnetic film which transitions to perpendicular magnetization at a temperature above a critical temperature due to in-plane magnetization at room temperature, and a film for perpendicular magnetization reproduction, It is characterized in that it is a magneto-optical recording medium that is sequentially laminated.

A seventeenth aspect of the present invention is a magneto-optical recording medium comprising at least a recording magnetic film and a reproducing magnetic film on a substrate, and reproducing by irradiating the magneto-optical recording medium with reproducing light. A magnetized film, a first auxiliary magnetic film that transitions to perpendicular magnetization at a temperature higher than a critical temperature at in-plane magnetization at room temperature, a non-magnetic material film, an auxiliary magnetic film made of an antiferromagnetic material having in-plane magnetization, and an in-plane magnetization at room temperature The magnetic recording medium is characterized in that it has a film layer such as a second auxiliary magnetic film that functions as a reproducing magnetic film that transitions to perpendicular magnetization at a critical temperature or higher, and is stacked in this order.

According to an eighteenth aspect of the present invention, in a magneto-optical recording medium having at least a recording magnetic film and a reproducing magnetic film on a substrate, and reproducing by irradiating a reproducing light onto the magneto-optical recording medium, A magnetized film, a first auxiliary magnetic film that transitions to perpendicular magnetization at a temperature above a critical temperature due to in-plane magnetization at room temperature, a second auxiliary magnetic film that transitions to perpendicular magnetization above a critical temperature due to in-plane magnetization at room temperature, It is characterized in that it is provided with a film layer such as an auxiliary magnetic film made of an antiferromagnetic material and a magnetic film for reproducing perpendicular magnetization, and is a magneto-optical recording medium laminated in this order.

The auxiliary magnetic film and the reproducing magnetic film made of the above-mentioned antiferromagnetic material are selected from a combination of a perpendicular magnetic film and a perpendicular magnetic film, and a combination of an in-plane magnetic film and an in-plane magnetic magnetic film. It is preferable to configure with a selected combination.

Further, the film made of the non-magnetic material is made of a material selected from materials used for a light reflection film, a heat insulating film, a dielectric film, a transparent protective film, a substrate material and the like of a magneto-optical recording medium. Is also good.

Next, the principle of recording and reproducing according to the present invention will be described.
The coercive force Ht of the perpendicularly magnetized magneto-optical recording film 10 and the reproducing magnetic film 24 used in the magneto-optical recording medium of the present invention decreases as the temperature of the magnetic film increases, and the coercive force becomes higher than the Curie temperature Tc. It has the property of becoming zero. At a temperature lower than the Neel temperature Tn or the blocking temperature Tb, the auxiliary magnetic film 30 made of an antiferromagnetic material exchange-couples with the adjacent magnetic layer to be stacked, and strongly fixes the magnetization direction of the adjacent magnetic layer. When the temperature exceeds the Neel temperature Tn or the blocking temperature Tb,
The auxiliary magnetic film 30 made of an antiferromagnetic material becomes paramagnetic,
The exchange coupling force with the adjacent magnetic layer disappears.

In the magneto-optical recording medium of the present invention, as a means for reproducing the recording magnetic domains recorded on the magneto-optical recording layer 10, the recording magnetic domains are transferred to the reproducing layer magnetic film 24 formed on the magneto-optical recording medium. The read-out reproduction is performed by detecting the polarization Kerr rotation angle of the reproduction laser light obtained from the transfer recording magnetic domain of the reproduction magnetic film 24 which has been enlarged. By the way, in order to obtain a reproduced signal having a large S / N ratio, the recording magnetic domain of the magneto-optical recording layer 10 is transferred from the magneto-optical recording layer 10 to the reproducing magnetic film 24, and at the stage of further expansion, the recording magnetic domain signal magnetic field is increased. External magnetization other than the recorded magnetic domain signal,
Noise such as a leakage magnetic field must be reduced to zero as much as possible. In order to reduce the noise and obtain a clearly transferred and enlarged recording magnetic domain, in order to limit the recording magnetic domain signal magnetic field from the magneto-optical recording layer 10 to an infinitely pure recording magnetic domain signal, another noise magnetic field is shut out to improve the efficiency. It is extremely effective to use the auxiliary magnetic film made of the antiferromagnetic material of the present invention as a laminated film of the magneto-optical recording layer as a means for good noise shielding or noise shielding.

The auxiliary magnetic film 30 made of an antiferromagnetic material
When an in-plane magnetization antiferromagnetic material is used, the magnetization direction of the in-plane magnetization magnetic film adjacent to the auxiliary magnetic film 30 is strongly fixed as it is. In the case of a perpendicular magnetization antiferromagnetic material, the direction of magnetization of the perpendicular magnetization magnetic film adjacent to the auxiliary magnetic film 30 is strongly fixed in the state. In order to make the recording magnetic field signal transferred to the magnetic film as pure as possible, it is necessary to complete the transfer in a short time within a limited temperature range with a transfer magnetic field strength equal to or higher than the coercive force of the reproducing magnetic film. After the transfer, it is necessary to enlarge the image without being affected by an external magnetic field.

The Neel temperature Tn or the blocking temperature Tb held by the auxiliary magnetic film 30 made of an antiferromagnetic material is:
It functions as an effective shutter to complete transfer in a very short time within a limited temperature range. That is, the strong exchange coupling force acting between the lamination of the reproducing magnetic film and the auxiliary magnetic film 30 made of the antiferromagnetic material is temporarily weakened or eliminated by the reproducing laser light, and the magnetization direction is changed to the recording magnetic domain. In order to follow the direction of the transfer magnetic field. That is, the auxiliary magnetic film 30 made of an antiferromagnetic material allows only the magnetic field of a pure recording magnetic domain to pass therethrough and be applied to the reproducing layer magnetic film 24, and the recording magnetic domain is transferred to the reproducing layer magnetic film 24. An important function of the auxiliary magnetic film 30 using an antiferromagnetic material is to weaken the exchange coupling force or to make the auxiliary magnetic film 30 made of an antiferromagnetic material paramagnetic at the moment of the change.

The material of the reproducing layer magnetic film 24 is a critical temperature Tcr2.
It is preferable to use a material having a coercive force smaller than the transfer magnetic field of the recording magnetic domain of the magneto-optical recording layer 10 at a temperature in the vicinity.
The car rotation angle of the recording magnetic domain transferred to the reproducing layer magnetic film 24 is read by the reproducing laser beam, and the recorded information is reproduced. In this way, a reproduced signal having a high S / N ratio can be obtained. In the present invention, the reproducing magnetic film 24 and the auxiliary magnetic film 30
Since the materials for the reproducing magnetic film 24 and the auxiliary magnetic film 30 are selected and used so that the critical temperature TCR2 and the Neel temperature Tn or the blocking temperature Tb satisfy TCR2 <Tn or Tb, the temperature profile in the medium shown in FIG. As shown in FIG. 7, the region of the reproducing layer magnetic film 24 which can be in the perpendicular magnetization state is a region where the temperature in the reproducing light spot region irradiated with the reproducing light has reached TCR2 or higher. That is, the reproducing layer magnetic film 24
In the region where the temperature reaches or exceeds the critical temperature TCR2, the in-plane magnetic domain cannot exist, and in the region where the temperature reaches or exceeds the critical temperature TCR2, the expansion of the transferred recording magnetic domain proceeds.

When this magneto-optical recording medium is irradiated with reproducing light of appropriate power so that the maximum heating temperature of the magnetic film becomes a desired temperature, the temperature of the reproducing layer magnetic film 24 becomes TCR2 or more and the perpendicular magnetization state becomes higher. There is a region that can be By selecting a magnetic material having a critical temperature TCR2 such that the temperature region is equal to or greater than the diameter of the recording magnetic domain M recorded in the magneto-optical recording film 10, and preferably equal to or greater than the reproducing light spot diameter, the reproducing layer magnetic film 24 is selected. Or the power of the reproduction light is set and used. The reproducing layer magnetic film 24 has a coercive force corresponding to the temperature distribution in the region of TCR2 or more, as shown in FIGS.
5, and has magnetic properties such that the value becomes sufficiently small in and near the region where the maximum temperature is reached. When the magneto-optical recording medium is irradiated with a reproducing laser beam, the reproducing layer auxiliary magnetic film 2 is formed in the reproducing layer magnetic film 24 when the perpendicular magnetization state becomes TCR2 or more.
Although the transfer magnetic domain (domain) of No. 4 expands, the transfer magnetic domain expands to a size at which the reproduction light can be read, for example, larger than the diameter of the reproduction light spot. For the reproducing layer magnetic film 24, a material having an optimum value of the element ratio uvw for the GduFevCow alloy is selected and used.

The magneto-optical recording film 10 has a magnetization distribution corresponding to a temperature distribution in a region of TCR2 or more, and has a magnetic property such that its value becomes sufficiently large in a region where the maximum temperature is reached and in the vicinity thereof. ing. Since the magnetic characteristics of each magnetic film are set as described above, only the magnetic domain M in the region where the temperature is high and the magnetization is sufficiently large in the magneto-optical recording film 10 is different from the magneto-optical recording film 10 acting in the region of the magnetic domain M and the auxiliary domain. Due to the exchange coupling force between the magnetic films 28 and the large magnetostatic coupling force between the magneto-optical recording film 10 or the auxiliary magnetic film 28 and the reproducing layer magnetic film 24, the temperature in the reproducing layer magnetic film 24 is high and the coercive force is sufficient. It is transferred to a small area. Thereby, a sufficient reproduction resolution can be obtained first.

Next, the magnetic domain transferred to the reproducing layer magnetic film 24 is changed due to the perpendicular magnetic anisotropy in the region of TCR2 or more and the exchange coupling force from the transferred magnetic domain as shown in FIG. It is thought to expand. After reproduction, that is, after the reproduction laser beam has moved, the read section is cooled to TCR2 or less, and the reproduction layer magnetic film 24 becomes an in-plane magnetized film.
Return to the state of (a).

The effect of the magnetic domain expansion of the reproducing layer magnetic film 24 is maximized when the transfer magnetic domain in the reproducing layer magnetic film 24 is expanded to a diameter larger than the reproducing light spot diameter. In this state, an extremely large reproduction output determined only by the figure of merit of the reproduction layer magnetic film 24 and the reproduction beam light, regardless of the size or shape of the magnetic domain recorded in the magneto-optical recording film 6, is obtained. Even at the temperature at the time of the reproducing operation as described above, the magneto-optical recording film 10
Has a sufficiently large coercive force, so that information recorded as magnetization is completely retained.

FIG. 10 (a) shows the magnetization state of each layer before the reproduction after writing the recording magnetic domain on the magneto-optical recording film 10 by the optical modulation recording method or the like. Next, the perpendicular magnetization recording signal of the magneto-optical recording film 10 is transferred to an area where the temperature in the auxiliary magnetic film 28 is not less than the critical temperature Tcr1 and not more than Tcr2 (FIG. 10).
(B)). Next, as shown in FIG. 10C, when a temperature profile in the medium generated by the irradiation of the reproduction light is taken into consideration, a magnetic domain having the same magnitude as or smaller than the perpendicular magnetization recording domain signal of the magneto-optical recording film 10 is obtained. Are transferred to the reproducing layer magnetic film 24, the Neel temperature Tn or the blocking temperature Tb of the antiferromagnetic auxiliary magnetic film 30, the critical temperature Tcr2 of the reproducing layer magnetic film 24, and the power of the reproducing light spot are set in advance. Set.

The magnetic domain transferred to the auxiliary magnetic film 28 is transferred to the reproducing layer magnetic film 24. In the present invention, the auxiliary magnetic film 28
And the reproducing layer magnetic film 24 has a critical temperature Tcr1>
Since it is set to be Tcr2, as shown in the temperature profile in the medium of FIG.
The region in the middle perpendicular magnetization state has a larger diameter than that in the auxiliary magnetic film 28. For this reason, FIG.
As shown in FIG. 7, the transfer magnetic domain 231 in the reproducing layer magnetic film 24 is magnetostatically coupled from the perpendicular magnetic anisotropy in the region of the reproducing layer magnetic film 24 where the perpendicular magnetization can be obtained and the perpendicular magnetization in the auxiliary magnetic film 28. Expanded with power.

This magnetic domain expansion is based on the fact that the in-plane magnetization of the region of the reproducing layer magnetic film 24 causes the magnetostatic coupling force from the recording magnetic domain signal 22 of the magneto-optical recording film 10 shown in FIG. It can be said that it is being promoted because it is weakening. Due to the magnetic domain expansion, a decrease in the amount of light contributing to the reproduction output by the magnetic mask of the in-plane magnetization is reduced.

The magnetic temperature curve B in FIG.
4 shows the temperature change of the coercive force in the vertical direction in the state having the perpendicular magnetization of No. 4. This coercive force is applied to the coercive force Hr of the magnetic domain of the pure magnetic film 24 for reproduction in the vertical direction.
The magnetic field Hw (in other words, the exchange coupling magnetic field in the in-plane direction of the reproducing layer) corresponding to the virtual magnetic field which is considered to be applied by the generation of the magnetic wall of Hr +
Hw. That is, Hr + Hw indicates a magnetic field necessary for performing magnetization reversal in a direction perpendicular to the film surface of the reproducing magnetic film 24. That is, the magnetization recorded on the magneto-optical recording layer 10 is directed in the direction ↓ (recording direction).
, The transfer magnetic field represented by Hex + Ht is Hr
Must be greater than + Hw or-(Hr + Hw) (magnetic domain transfer requirement). When the magnetization recorded in the recording layer is in the ↑ direction (erasing direction),
The negative transfer magnetic field represented by Hex-Ht must be smaller than the perpendicular coercive force Hr + Hw or-(Hr + Hw) of the reproducing layer (magnetic domain transfer requirement).

[0049]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments and examples of a magneto-optical recording medium and a reproducing method of the present invention will be described below with reference to the drawings.

[0050]

Embodiment 1 A first embodiment of the magneto-optical recording medium of the present invention is shown in FIG.
As shown in (a), a reflective film 8, a nonmagnetic film 29, an antiferromagnetic material auxiliary magnetic film 30, and a reproduction auxiliary magnetic film 24 used for reproduction are stacked on the magneto-optical recording film 10 in this order. UV-curable resin, silicon oxide (SiO2), silicon nitride (Si3N4)
The auxiliary magnetic film for reproduction 24 is covered with silicon nitride (Si3N4), aluminum oxide (Al2O
3) A dielectric film 3 selected from a material such as aluminum nitride (AlN) or the like and a substrate 1 made of a polycarbonate resin or the like are formed. One side of the substrate 1 has a pre-forming 2
Is formed, and the dielectric film 3 and the auxiliary magnetic film for reproduction 24 are arranged and formed on the side of the pre-forming 2 side. For the magneto-optical recording film 10, an alloy of TbFeCo or, if necessary, an alloy of TbFeCo with addition of Nb, Cr or the like is used. The reflective film 8 is made of Al metal, an AlTi alloy, or the like, and the nonmagnetic film 29 is made of a conductive heat control material such as silicon nitride (Si3N4), aluminum oxide (Al2O3), or aluminum nitride (AlN). GdTb is used for the auxiliary magnetic film 24 for reproduction.
An alloy such as FeCo or GdFeCo is selected and used.
MnO, Cr 2 O 3,
FeS, FeCl2, MnAs, Tb, Dy, Ho, E
r, Tm, Tb alloy, Dy alloy, Ho alloy, Er alloy,
It is used by selecting from a compound such as a Tm alloy, an element, or an alloy. In the antiferromagnetic material auxiliary magnetic film 30, the magnetic moments of the magnetic atoms adjacent to each other in the crystal have a negative exchange interaction, so that the magnetisms are arranged in antiparallel and cancel each other out. When the temperature of the antiferromagnetic material auxiliary magnetic film 30 increases, the magnetic susceptibility increases, but becomes paramagnetic or non-magnetic at the Neel temperature Tn.

The magneto-optical recording medium of the present invention can be applied to all standardized media. In particular, the magneto-optical recording medium has an outer diameter of 120 mm or less, and has a thickness of 0.6 mm and a thickness of 0.6 mm.
1G thinner than 1.0mm such as 4mm, 0.8mm
It is suitable for high-density recording of B (gigabyte) / square inch (scare inch) or more.

In the laminated structure of the magneto-optical recording medium of the present invention shown in FIG. 1A, recording and reproduction are performed by a recording and reproducing apparatus using an ordinary optical head holding an objective lens 301. However, for a recording / reproducing apparatus using an optical head that uses both an objective lens 301 and an SIL (also known as a solid immersion lens, solid immersion lens, solid immersion lens, etc.) 302, the laminated film structure shown in FIG. Magneto-optical disks must be used. The magneto-optical disk shown in FIG. 1B has a thin transparent protective film, a thin transparent dielectric film 3, or a laminated film of a thin transparent protective film and a dielectric film on the side where the reproducing laser beam is incident. Reproducing layer magnetic film 24
The substrate 1 coated on the outer surface of the substrate 1 and subjected to the pre-matching 2 is used as a protective film on the outer surface of the magneto-optical recording film 10.

FIG. 2 is a temperature characteristic diagram of the coercive force of the magnetic film layer. Curve A shows the temperature characteristic of the coercive force of the magneto-optical recording film 10 and curve B shows the temperature characteristic of the coercive force of the reproducing layer magnetic film 24. The reproducing layer magnetic film 24 has in-plane magnetization up to the critical temperature Tcr2, and transitions to perpendicular magnetization above Tcr2. The recording magnetic domain of the magneto-optical recording film 10 is T
The image is transferred to the reproducing layer magnetic film 24 at a temperature of at least cr2 and reproduced. Since the Curie temperature Tc0 of the magneto-optical recording film 10 is lower than the Curie temperature Tc1 of the reproducing layer magnetic film 24, the temperature at which the recording magnetic domain is transferred by the irradiation of the reproducing laser beam is T1.
It is preferable to set the following. The recorded magnetic domain after reproduction disappears when the temperature of the reproduction layer magnetic film 24 becomes Tcr2 or lower.

The process of reproducing the recording magnetic domain 22 of the information recorded on the magneto-optical disk shown in FIGS. 1A and 1B is as shown in FIG.
Shown in FIG. 3A shows a state of the recording magnetic domains 22. When the reproducing laser beam is irradiated from the substrate 1 side, the reproducing of the antiferromagnetic material auxiliary magnetic film 30 having the in-plane magnetization as shown in FIG. The portion irradiated with the laser beam becomes paramagnetic beyond the nail point, and exchanged coupling with the reproducing layer magnetic film 24 is broken, thereby generating a hatched portion.
4, a transfer 23 of the recording magnetic domain is formed. Next, the recording magnetic domain transfer 23 of the reproducing layer magnetic film 24 is denoted by 231 in FIG.
And it enlarges like 232 of FIG.3 (d). When the heating temperature of the antiferromagnetic material auxiliary magnetic film 30 by the reproduction laser beam is high and the extent of the portion beyond the nail point is expanded, as shown in FIG. When the hatched portion is enlarged and the reproducing laser beam is fine and the power is low, the state of the hatched portion of the antiferromagnetic material auxiliary magnetic film 30 shown in FIG.

The critical temperature Tcr2 and the nail point Tn in FIG. 3 have a relationship of Tcr2 <Tn.

[0056]

[Embodiment 2] FIG. 4 shows a laminated film configuration of a magneto-optical disk used in Embodiment 2 of the present invention. This laminated film configuration is described in Example 1.
The first auxiliary magnetic film 128 is inserted between the magneto-optical recording layer 10 and the light reflection layer 8 of the medium, and the non-magnetic layer 29 is removed. Others are the same as FIG. 1 (a). The first auxiliary magnetic film 128 shown in FIG. 4 has perpendicular magnetization at room temperature, but transitions to in-plane magnetism at the critical temperature Tcr1, and becomes critical temperature Tcr1.
The above shows in-plane magnetism. A curve D in FIG. 5 shows the relationship between the temperature of the first auxiliary magnetic film 128 and the perpendicular magnetization coercive force. That is, the first auxiliary magnetic film 128 has the critical temperature Tcr1 and the curve C
A material that can be set to be higher than the critical temperature Tcr2 of the reproducing layer magnetic film 24 shown in FIG. The first auxiliary magnetic film 128 has T
It is preferable to use one having a function of transferring a recording magnetic domain signal of the magneto-optical recording layer 10 at a temperature of cr1 or lower. The anti-ferromagnetic material auxiliary magnetic film 30 has a nail point Tn at a temperature T shown in FIG.
A material having a value corresponding to the temperature between cr2 and Tcr1 is used.

FIG. 6A shows a state of magnetization of each magnetic film of the magneto-optical disk in which the recording magnetic domains 22 are recorded on the magneto-optical recording layer 10. The first auxiliary magnetic film 12 is irradiated with a reproduction laser beam.
8, when the recording magnetic domain is transferred, the recording magnetic domain signal magnetic field is changed to the antiferromagnetic material auxiliary magnetic film 30 as shown in FIG.
And the reproducing layer magnetic film 24. Reproducing layer magnetic film 2
4 is exchange-coupled with the antiferromagnetic material auxiliary magnetic film 30, and at least the critical temperature T of the reproducing layer magnetic film 24.
The data up to cr2 is not transferred to the reproducing layer magnetic film 24. The temperature due to the reproducing laser beam is the critical temperature Tc of the reproducing layer magnetic film 24.
r2 and the Neel point T of the antiferromagnetic material auxiliary magnetic film 30
When the temperature reaches about n, the transfer of the recording magnetic domain signal to the portion of the reproducing layer magnetic film 24 is started.
When the temperature of the anti-ferromagnetic material auxiliary magnetic film 30 is higher than the nail point Tn, the transfer of the recording magnetic domain signal to the reproducing layer magnetic film 24 becomes clear as shown in FIG. Next, the temperature of the portion of the first auxiliary magnetic film 128 irradiated with the reproducing laser beam is changed to the critical temperature Tc.
At r1 or more, the first auxiliary magnetic film 128 transitions to in-plane magnetization, so that the recording magnetic domain signal magnetic field to the reproducing layer magnetic film 24 is cut off, and noise such as an external magnetic field and a leakage magnetic field is also cut off. Therefore, as shown in FIGS. 6C and 6D, Tn and Tc
The recording magnetic domain transferred to the reproducing layer magnetic film 24 at the temperature of r1 is represented by 231 and 232 as shown in FIG.
It expands to the region where the critical temperature Tcr2 accompanying the thermal diffusion proceeds. At this time, when the state of the heating temperature of the antiferromagnetic material auxiliary magnetic film 30 by the reproduction laser beam is high and the spread beyond the nail point is widened, as shown in FIG. Area 3 with transition to 30 paramagnetism
When the reproduction laser beam is small and the power is low, it is assumed that the area 332 of the antiferromagnetic material auxiliary magnetic film 30 transitions to paramagnetism as shown in FIG. 6D.

The critical temperatures Tcr1 and Tcr2 and the nail point Tn in FIG. 6 have a relationship of Tcr2 <Tn <Tcr1.

[0059]

Embodiment 3 Regarding the laminated film configuration of the recording layer of the magneto-optical disk, the first auxiliary magnetic film 128 of the magneto-optical disk used in Example 2 was replaced with the anti-ferromagnetic material auxiliary magnetic film 30 and the reproducing layer magnetic film 24. In between, the antiferromagnetic material auxiliary magnetic film 3
The laminated film configuration was manufactured as shown in FIG. 17 by using the perpendicularly magnetized antiferromagnetic material 130 as the material No. 0. When the recording magnetic domain recorded on the magneto-optical disk is reproduced by irradiating the reproducing laser beam, the recording magnetic domain signal of the magneto-optical recording layer 10 is transferred to the first auxiliary magnetic film 128 because of the perpendicular magnetization at room temperature and the critical magnetization. The material of the first auxiliary magnetic film 128 which changes to in-plane magnetization at the temperature Tcr1 has a critical temperature Tc higher than the nail point Tn of the perpendicular magnetization antiferromagnetic material auxiliary magnetic film 130.
This is a case where a device that holds r1 is used. In this case, when the temperature of the perpendicular magnetization antiferromagnetic material auxiliary magnetic film 130 reaches the vicinity of the nail point Tn, the recording magnetic domain signal is transferred to the first auxiliary magnetic film 128 as shown in FIG. The critical temperature Tcr2 of the reproducing layer magnetic film 24 is lower than the critical temperature Tcr1 of the first auxiliary magnetic film 128, and the Neal point T of the perpendicular magnetization antiferromagnetic material auxiliary magnetic film 130
If a magnetic material lower than n is used, the transfer of the recording magnetic domain signal and the enlarged recording magnetic domain 233 can be obtained as shown in FIG. Others are the same as the second embodiment.

[0060]

Embodiment 4 With respect to a magneto-optical disk having the same laminated film configuration as the recording layer of the magneto-optical disk used in Embodiment 3, an anti-ferromagnetic material 30 having in-plane magnetization was used for the anti-ferromagnetic material auxiliary magnetic film.
At room temperature, the first auxiliary magnetic film has a critical temperature Tcr1 due to in-plane magnetization at room temperature.
The material 28 which changes to perpendicular magnetization at the time of was used. When the recording magnetic domain recorded on the magneto-optical disk is reproduced by irradiating the reproducing laser beam, the recording magnetic domain signal of the magneto-optical recording layer 10 is transferred to the first auxiliary magnetic film 28 because of the critical temperature at which the magnetization transitions to perpendicular magnetization. This is the case where Tcr1 has been reached. That is, the anti-ferromagnetic material auxiliary magnetic film 30 having in-plane magnetization has a nail point Tn.
Preferably maintain a temperature value equal to or higher than Tcr1. In this case, when the temperature of the antiferromagnetic material auxiliary magnetic film 30 of in-plane magnetization reaches near the nail point Tn, the recording magnetic domain signal is transferred to the first auxiliary magnetic film 28 as shown in FIG. . For the reproducing layer magnetic film 24, it is preferable to use a magnetic material whose critical temperature Tcr2 is lower than the critical temperature Tcr1 of the first auxiliary magnetic film 28, as shown in FIG.
As shown by, transfer of the recording magnetic domain signal, the enlarged recording magnetic domain 23
4 is obtained. Others are the same as the third embodiment.

[0061]

[Embodiment 5] FIG. 8 shows a laminated film configuration of a magneto-optical disk used in Embodiment 5 of the present invention. The configuration of this laminated film is the same as that of FIG. 4, but the auxiliary magnetic film 28 is made of a magnetic material which has in-plane magnetization at room temperature and transitions to perpendicular magnetization at the critical temperature Tcr1. Uses an in-plane magnetization antiferromagnetic material. The reproducing layer magnetic film 24 in FIG. 8 also has in-plane magnetization at room temperature, but transitions to perpendicular magnetism at the critical temperature Tcr2. The critical temperature Tcr2 is, as apparent from the temperature characteristic curve B of coercive force in FIG. Critical temperature Tcr of magnetic film 28
A magnetic material lower than 1 is used. A curve C in FIG. 9 shows the relationship between the temperature of the auxiliary magnetic film 28 and the perpendicular magnetization coercive force. That is, the critical temperature Tcr1 of the auxiliary magnetic film 28 can be set higher than the critical temperature Tcr2 of the reproducing magnetic layer 24 shown by the curve B, and is higher than the nail point Tn of the in-plane magnetization antiferromagnetic material auxiliary magnetic film 30. It is preferable to use a material that can be set low. The anti-ferromagnetic material auxiliary magnetic film 30 having in-plane magnetization has a nail point Tn at temperatures Tcr2 and Tc shown in FIG.
If the material is higher than r1, a recording magnetic domain with very little noise can be transferred to the reproducing layer magnetic film 24.

FIG. 10A shows a state of magnetization of each magnetic film of the magneto-optical disk in which the recording magnetic domains 22 are recorded on the magneto-optical recording layer 10. At the point when the recording magnetic domain is transferred to the auxiliary magnetic film 28 by the irradiation of the reproduction laser beam, the recording magnetic domain signal magnetic field reaches the in-plane magnetization antiferromagnetic material auxiliary magnetic film 30 as shown in FIG. However, no influence of the recording magnetic domain signal magnetic field appears on the reproduction layer magnetic film 24 exchange-coupled with the in-plane magnetization antiferromagnetic material auxiliary magnetic film 30. It is preferable that the transfer is not performed to the reproducing layer magnetic film 24 at least up to the nail point Tn of the antiferromagnetic material auxiliary magnetic film 30 having the in-plane magnetization. The temperature of the reproducing laser beam is
When the temperature reaches about the temperature between the critical temperature Tcr2 and the nail point Tn of the in-plane magnetization antiferromagnetic material auxiliary magnetic film 30, transfer of the recording magnetic domain signal to the portion of the reproducing layer magnetic film 24 is started. As shown in FIG. 10C and FIG. 10D, when a temperature equal to or higher than the nail point Tn is applied to the in-plane magnetization antiferromagnetic material auxiliary magnetic film 30, a recording magnetic domain signal to the reproducing layer magnetic film 24 is transmitted. Transcription becomes clear. Therefore, FIG.
(C), the recording magnetic domain transferred to the reproducing layer magnetic film 24 between the temperatures Tn and Tcr1 as shown in FIG. 10 (d) is accompanied by the thermal diffusion on the reproducing layer magnetic film 24 as indicated by 231 and 232. The region expands to the region where the critical temperature Tcr2 advances. At this time, when the state of the heating temperature of the antiferromagnetic material auxiliary magnetic film 30 having the in-plane magnetization by the reproducing laser beam is high, and the portion beyond the nail point expands, as shown in FIG. The area of the antiferromagnetic material-assisted magnetic film 30 which has transitioned to paramagnetism is enlarged, and when the reproducing laser beam is fine and has low power, the in-plane magnetization antiferromagnetic material assisted as shown in FIG. It is assumed that the state of the magnetic film 30 is changed to the paramagnetic state.

The critical temperatures Tcr1 and Tcr2 and the nail point Tn in FIG. 6 have a relationship of Tcr2 <Tcr1 <Tn.

[0064]

Embodiment 6 With respect to a laminated film of recording layers constituting a magneto-optical disk, the magneto-optical recording layer 10 has an auxiliary magnetic film 28 which has in-plane magnetization at room temperature and transitions to perpendicular magnetization at a critical temperature Tcr1, and an anti-in-plane magnetization. A layered structure of a magnetic film as shown in FIG. 7 was manufactured in which the ferromagnetic material auxiliary magnetic film 30 and the reproducing layer magnetic film 24 were directly contacted in this order. The method of transferring, enlarging, and reproducing the recording magnetic domain recorded on the magneto-optical disk by the reproducing laser beam, the reproducing mechanism, the reproducing characteristics, and the obtained effects are the same as those in the fifth embodiment.

[0065]

Seventh Embodiment A non-magnetic film 29 is inserted between the auxiliary magnetic film 28 and the magneto-optical recording film 10 in the recording film layer of the magneto-optical disk used in the fifth embodiment, as shown in FIG. A magneto-optical disk was constructed in which the first auxiliary magnetic film 32 was covered with a non-magnetic film so that the first auxiliary magnetic film 32 did not directly contact another magnetic film.

The first auxiliary magnetic film 32 is made of a magnetic material which has in-plane magnetization at room temperature and transitions to perpendicular magnetization at the critical temperature Tcr1, and the anti-ferromagnetic material auxiliary magnetic film 30 is an anti-ferromagnetic material having in-plane magnetization. Is used.

FIG. 14A shows the state of magnetization of each magnetic film of the magneto-optical disk in which the recording magnetic domains 22 are recorded on the magneto-optical recording layer 10. The recording magnetic domain must be transferred to the first auxiliary magnetic film 32 by irradiating the reproduction laser light to first heat the first auxiliary magnetic film 32 to the critical temperature Tcr1. On the other hand, since the critical temperature Tcr2 of the reproducing magnetic layer 24 is lower than Tcr1, the temperature of the reproducing magnetic film 24 has already reached the critical temperature Tcr2 or higher. Since the material whose nail point Tn is set to be higher than Tcr1 is used for the in-plane magnetization antiferromagnetic material auxiliary magnetic film 30, after the recording magnetic domain is transferred to the first auxiliary magnetic film 32, FIG. As shown in ()), a paramagnetic broadened portion is generated in the in-plane magnetization antiferromagnetic material auxiliary magnetic film 30 and the in-plane magnetization antiferromagnetic material auxiliary magnetic film 3 is formed.
In the reproducing layer magnetic film 24 exchange-coupled to 0, the recording magnetic domain is transferred and expanded in a portion of the reproducing layer magnetic film 24 opposite to the paramagnetic expansion portion of the antiferromagnetic material auxiliary magnetic film 30. The temperature due to the reproduction laser beam is changed to the first auxiliary magnetic film 32.
When the temperature reaches about the temperature between the critical temperature Tcr1 and the nail point Tn of the in-plane magnetization antiferromagnetic material auxiliary magnetic film 30, the transfer of the recording magnetic domain signal to the reproducing layer magnetic film 24 is started.

[0068]

[Embodiment 8] A magneto-optical device in which a reproducing auxiliary magnetic layer 240 is added to the reproducing laser beam incident side surface of the reproducing magnetic layer 24 of the laminated film of the magneto-optical disk used in the embodiment 7 shown in FIG. The disk is shown in FIG. In this embodiment, as shown in FIG. 15, the reproduction signal obtained by performing the transfer expansion of the recording magnetic domain on the reproduction layer magnetic film 24 of the magneto-optical disk in Embodiment 7 is further retransferred to the reproduction auxiliary magnetic layer 240, as shown in FIG. This is a method of reproducing a recording magnetic domain recorded in the reproduction auxiliary magnetic layer 240 by a reproduction laser beam.

[0069]

Ninth Embodiment The reproducing layer magnetic film 24 is removed from the magneto-optical disk laminated film used in the eighth embodiment shown in FIG.
A magneto-optical disk having a laminated film structure as shown in FIG. 13 was manufactured. The auxiliary magnetic film 2 of perpendicular magnetization is used as the magnetic film for reproduction.
40 is used. In the signal recorded on the reproduction auxiliary magnetic film 240, the recording domain magnetic field of the magneto-optical recording layer 10 is temporarily transferred to the first auxiliary magnetic film 32, and then the in-plane magnetization of the antiferromagnetic material auxiliary magnetic film 30 When the temperature rises to around Tn or higher, the reproducing laser beam incident portion of the in-plane magnetization antiferromagnetic material auxiliary magnetic film 30 exchange-coupled with the auxiliary reproducing magnetic layer 240 becomes paramagnetic. Next, the recording magnetic domain magnetic field from the magneto-optical recording layer 10 or the first auxiliary magnetic film 32 causes the recording portion of the reproduction auxiliary magnetic layer 240, in which the exchange coupling between the in-plane magnetization and the antiferromagnetic material auxiliary magnetic film 30 has disappeared, to be as shown in FIG.
As shown in FIG. 6, a recording magnetic domain signal is recorded. In this embodiment, the recording magnetic domain transferred to the first auxiliary magnetic film 32 of the magneto-optical disk in the eighth embodiment is re-transferred to the reproduction auxiliary magnetic layer 240 as shown in FIG. This is a method of reproducing the recording magnetic domain recorded in the recording medium by a reproducing laser beam. Others are the same as the seventh embodiment.

[0070]

Embodiment 10 As shown in FIG. 11, the first auxiliary magnetic film 3
2 so as not to make direct contact with other magnetic films.
A configuration in which the auxiliary magnetic film 32 is covered with a non-magnetic film;
The auxiliary magnetic film 32 has in-plane magnetization at room temperature and a critical temperature Tc.
A magneto-optical disk was fabricated using a magnetic material that transitions to perpendicular magnetization at r1 and using an antiferromagnetic material auxiliary magnetic film 130 made of a perpendicular magnetization antiferromagnetic material and a perpendicular magnetization magnetic film 124 as a reproducing magnetic film. .

The feature of such a magnetic film configuration is that the perpendicularly magnetized magnetic film 124 as the reproducing magnetic film is strongly exchange-coupled with the antiferromagnetic material auxiliary magnetic film 130 made of the perpendicularly magnetized antiferromagnetic material. And that the first auxiliary magnetic film 32 functions as a shutter that blocks magnetic fields such as the magnetic field of the magneto-optical recording layer 10, an external magnetic field, and a leakage magnetic field.

FIG. 20A shows a state of magnetization of each magnetic film of the magneto-optical disk in which the recording magnetic domains 22 are recorded on the magneto-optical recording layer 10. When the reproduction laser beam is irradiated, first, FIG.
As shown in (b), the critical temperature T is applied to the first auxiliary magnetic film 32.
A portion that is heated to cr1 and transitions to perpendicular magnetization occurs. At this time, if the antiferromagnetic material auxiliary magnetic film 130 has not reached the nail point Tn, the perpendicular magnetic
24 and a strong exchange coupling is maintained. However, when a portion reaching the nail point Tn occurs in the antiferromagnetic material auxiliary magnetic film 130, as shown in FIG. 20C, the portion of the antiferromagnetic material auxiliary magnetic film 130 becomes paramagnetic and becomes vertical. The magnetized magnetic film 124 becomes responsive to the magnetic field from the magneto-optical recording layer 10, the first auxiliary magnetic film 32, and the like, and the recording magnetic domain signal is transferred to the perpendicularly magnetized magnetic film 124. Recording magnetic domains 231 and 2 transferred to perpendicular magnetic film 124
As shown in FIGS. 20 (c) and 20 (d), the size of the perpendicular magnetization 32 corresponds to the state where the area of the portion reaching the nail point Tn of the antiferromagnetic material auxiliary magnetic film 130 is expanded. The recording magnetic domain transferred to the magnetic film 124 of FIG.

The condition for enlarging the transferred recording magnetic domain is such that the state of the heating temperature of the perpendicular magnetization antiferromagnetic material auxiliary magnetic film 130 by the reproduction laser beam is high, and the spread of the area beyond the nail point is expanded. 20C, the paramagnetized area of the perpendicular magnetization antiferromagnetic material auxiliary magnetic film 130 is expanded as shown in FIG. 20C, and when the reproducing laser light beam is fine and the power is low, as shown in FIG. It is assumed that the paramagnetic area of the perpendicular magnetization antiferromagnetic material auxiliary magnetic film 130 becomes small.

[0074]

Embodiment 11 A magneto-optical recording medium according to this embodiment is shown in FIG.
1A and 1B, a reflective film 8, a non-magnetic film 29, an antiferromagnetic material auxiliary magnetic film on a magneto-optical recording film 10, and a reproducing film used for reproducing. The magneto-optical recording film 1 has a structure in which auxiliary magnetic films are stacked in this order.
0 is an ultraviolet curable resin, silicon oxide (SiO2),
A dielectric film selected from materials such as silicon nitride (Si3N4), aluminum oxide (Al2O3), aluminum nitride (AlN), and the like is covered with a protective film using silicon nitride (Si3N4) or the like, and the outer surface of the auxiliary magnetic film for reproduction is formed on the outer surface. A film 3 and a substrate 1 made of a polycarbonate resin or the like are formed. A pre-formatting 2 is formed on one side of the substrate 1, and a dielectric film 3 and a reproducing auxiliary magnetic film are arranged and formed on the pre-formatting 2 forming side. As the antiferromagnetic material auxiliary magnetic film of the magneto-optical recording medium of this embodiment, an auxiliary magnetic film 130 made of a perpendicular magnetization antiferromagnetic material is used. The auxiliary magnetic film for reproduction used for reproduction is the auxiliary magnetic film for reproduction 124 of perpendicular magnetization.

FIG. 21 shows a process of reproducing the recorded magnetic domains 22 recorded on the magneto-optical disk of the embodiment. FIG. 21 (a)
Represents the magnetization state of each magnetic film of the magneto-optical recording medium on which the recording magnetic domain 22 before recording is recorded. When the reproducing laser beam is irradiated from the substrate 1 side, the portion of the perpendicularly magnetized antiferromagnetic material auxiliary magnetic film 130 irradiated with the reproducing laser beam as shown in FIG. A portion indicated by oblique lines occurs in which exchange coupling with the perpendicular magnetization reproducing layer magnetic film 124 is broken, and a portion of the perpendicular magnetization reproducing layer magnetic film 124 stacked in contact with the oblique line portion has a magneto-optical recording layer. The transferred recording magnetic domains 23 formed by the ten recording magnetic domain magnetic fields are formed. 21 (c), and FIG. 21 (c).
The image is enlarged as indicated by 232 in FIG. When the area of the area exceeding the nail point Tn greatly expands due to the high heating temperature of the perpendicular magnetization antiferromagnetic material auxiliary magnetic film 130 by the reproduction laser beam, as shown in FIG. The transfer recording magnetic domain of the perpendicular magnetization reproduction layer magnetic film 124 expands following the enlarged area of the hatched portion of the ferromagnetic material auxiliary magnetic film 130. When the reproducing laser beam is small and the power is low, the area of the hatched portion of the perpendicular magnetization antiferromagnetic material auxiliary magnetic film 130 becomes small as shown in FIG. Of the transfer recording magnetic domain is also reduced.

The materials, manufacturing methods, operating means, measuring methods, environmental conditions, and others used in the above Examples 1 to 11 were performed as described below.

As the transparent substrate 1 used in the magneto-optical recording medium of the present invention, for example, a transparent resin material such as polycarbonate or amorphous polyolefin formed into a desired shape, or a glass plate formed into a desired shape is used. Any substrate having a light-transmitting property, such as a substrate in which a transparent resin film having a desired preformat pattern 2 transferred thereon is adhered to one side of the substrate, can be used. The dielectric film 3 is provided for causing a reproduction light beam to cause multiple interference in the film and increasing the apparent Kerr rotation angle, and is made of, for example, Si 3 N 4 having a larger refractive index than the transparent substrate 1. It can be formed of an inorganic dielectric. The protective film is for protecting a film body laminated between the substrate and the protective film from a chemical adverse effect such as corrosion, and is made of, for example, a Si3N4 film. The magneto-optical recording film 10 is a perpendicular magnetization film exhibiting perpendicular magnetic anisotropy at a temperature equal to or higher than room temperature. For example, TbFeCo, D
An amorphous alloy of a rare earth and a transition metal such as yFeCo and TbDyFeCo is most preferable, but other known magneto-optical recording materials such as an alternately stacked Pt film and a Co film or a garnet-based oxide magnetic material may be used. it can.

The auxiliary magnetic film 28 and the reproducing layer magnetic film 24
From room temperature (RT) to a certain critical temperature above room temperature (Tcr)
Up to 2), the film is an in-plane magnetized film, and has a magnetic property of transitioning to a perpendicular magnetized film at Tcr2 or more. In this specification, room temperature refers to an ambient temperature at which a magneto-optical recording medium is usually used, and varies depending on a place of use, and is not particularly limited to a specific temperature.

ΘKR / θ obtained from the Kerr effect hysteresis loop when an external magnetic field is applied in a direction perpendicular to the film surface.
Examining the temperature dependence of KS (θKR: residual Kerr rotation angle, θKS: saturation Kerr rotation angle), the materials of the auxiliary magnetic film are, for example, GdFeCo, GdFe, GdTbFeC.
o, an amorphous alloy of a rare earth such as GdDyFeCo and a transition metal is most preferable.

The dielectric film 3, the reproducing layer magnetic film 24, the auxiliary magnetic film 28, the magneto-optical recording film 10, and the protective film 7 can be formed by a dry process such as continuous sputtering using a magnetron sputtering device.

The auxiliary magnetic film 28 of a magneto-optical recording medium, that is, a magneto-optical disk is shown. The sample is composed of a dielectric film made of a SiN film, a reproducing magnetic film made of a Gd25Fe56Co19 film (II), an auxiliary magnetic film made of a Gd28Fe53Co19 (I) film, and a Tb21Fe66Co13 film on a glass substrate having a preformat pattern. A magneto-optical recording film,
A protective film made of a SiN film was sequentially formed by sputtering to form a protective film. Table 1 shows the thickness and magnetic characteristics of each auxiliary magnetic film and magneto-optical recording film in this case. In the table, Tc represents the Curie temperature, and Tcr represents the critical temperature at which the in-plane magnetic film of the reproducing layer magnetic film changes to a perpendicular magnetic film or the perpendicular magnetic film changes to an in-plane magnetic film.

(Table 1) Material Thickness TC TCR (nm) (° C.) (° C.) Magneto-optical recording film TbFeCo 50 270-Auxiliary magnetic film GdFeCo (I) 70> 400 150 Reproducing layer magnetic film GdFeCo (II) 60> 400 90 A test was performed by using an optical magnetic field modulation method in which an external magnetic field was modulated in accordance with a recording signal while recording was performed while irradiating a laser beam in a pulsed manner at a constant period to a data recording area of the disk manufactured as described above. The signal was recorded. The duty ratio of the recording light pulse was 50%. Test signals were applied so that recording marks of various recording mark lengths were formed. Next, using a pickup having a numerical aperture of the objective lens = 0.55, laser wavelengths of 340, 640, 780 nm, etc., a linear velocity of 7.5 m / sec and a reproduction power of 2.5 m
W, recording marks of various lengths were reproduced by setting the externally applied magnetic field to zero during reproduction. Regeneration CN ratio (C: carrier level,
N: noise level) was measured.

In the sample disk according to the present embodiment (data is a solid line), it was found that a remarkably high reproduction C / N was obtained even when the recording mark length was 0.2 μm. Therefore, according to the present invention, extremely small recording marks exceeding the conventional reproduction limit can be reproduced, and the recording density can be improved.

As a light source for recording and reproduction, a wavelength of 680 is used.
An optical head having a nm and a lens numerical aperture of 0.55 was used. For recording on the magneto-optical disk, an optical pulse intensity modulation method was used. Recording was performed at a linear velocity of 5 m / s, a recording period of 320 ns, a recording laser power of 7.5 mW, a pulse width of 53.3 ns, and a recording magnetic field of 500 Oe.

The 0.8 μm recording magnetic domains were recorded at 0.8 μm intervals corresponding to data such as 1 and 0.

This recorded magnetic domain was reproduced under the following reproducing conditions. The linear velocity is 5.0 m / s, the reproducing laser power is 1.5 mW as low power Pr1 for magnetic domain expansion, and 3.5 as high power Pr2 for magnetic domain reduction (or disappearance).
Modulated to two power levels of mW. The modulation cycle of the reproduction power is 160 ns, and 150 ns at low power Pr1.
Irradiation was performed at a high power Pr2 for 10 ns. As the reproducing magnetic field, a constant DC magnetic field was used, and about 80 Oe was applied in the recording direction. This magnetic field can be substituted by a leakage magnetic field from the objective lens / actuator.

From the reproduced waveform, it was found that the signal increased only in the portion where the recording magnetic domain was present, and was not increased where the recording magnetic domain was not present. This means that the recording magnetic domain is transferred and expanded in the reproducing layer only when the reproducing light scans the portion where the recording magnetic domain of the recording track exists. Further, the reproduced signal has been amplified to a magnetic super-resolution mode, that is, about 1.5 times as large as the reproduced signal when the magnetic domain transferred by the magnetic domain is reproduced without being enlarged. This effect of amplifying the reproduced signal is remarkably effective in a finer recording magnetic domain.
Even when a small magnetic domain of 4 μm or less is recorded, 80% of the saturation amplitude (the difference between the reproduction signal when all the magnetizations of the reproduction layer are downward and the reproduction signal when all the magnetizations of the reproduction layer are upward). (To the saturation amplitude ratio) was obtained.

The reproduction conditions in the above embodiment can be explained as follows. That is, a temperature region in which magnetic domain transfer and magnetic domain expansion occur at low power Pr1 of the power-modulated reproducing light, that is, a temperature at which the reproducing layer is heated to Tcr2 = 175 ° C. to Tc0mp = 240 ° C. and magnetic domain disappears at high power Pr2. It is heated from a temperature exceeding a region (area c), that is, Tcomp (240 ° C.) to Tc0 = 270 ° C. A DC magnetic field of about 80 Oe applied in the recording direction positions the magnetic temperature curves A and B in the relationship as shown in the figure. That is, the relationship between the magnetic temperature characteristics of the magneto-optical disk used in this embodiment and the applied DC magnetic field satisfies the following requirements (3) and (4). Hereinafter, requirements necessary for the reproducing method described in this embodiment will be listed. The magnetic characteristics of the reproducing layer and the recording layer of the magneto-optical recording medium used in this embodiment satisfy the following requirements (1) and (2) as described above.

(1) The reproducing layer magnetized in the film plane direction at least at room temperature has a compensation temperature Tc0mp between the critical temperature Tcr2 for magnetizing in the vertical direction and the Curie temperature Tc0.

(2) The Curie temperature Tc of the recording layer is between the compensation temperature Tc0mp of the reproducing layer and the Curie temperature Tc0 of the reproducing layer.

In this embodiment, the above requirements (1) and (2) were satisfied by forming a magneto-optical disk using the specific material and applying a DC magnetic field of 80 Oe in the recording direction. Any material can be used as long as it can satisfy the conditions (1) and (2) and a magneto-optical recording medium having a laminated structure and an external magnetic field applied during reproduction. The DC magnetic field applied at the time of reproduction may be not only in the recording direction but also in the erasing direction.

In the reproducing method of the present invention, by modulating the reproducing light power intensity under a DC magnetic field,
The processes of (a) magnetic domain transfer, (b) magnetic domain enlargement, and (c) disappearance of the transferred magnetic domain are performed. The time during which these processes are performed depends not only on the magnetic properties of the recording layer, the auxiliary magnetic layer, and the reproducing layer, but also on the recording layer, the auxiliary magnetic layer, the reproducing layer, the nonmagnetic layer,
It also depends on the temperature rise rate of the dielectric layer, the protective layer, and other stackable magnetic or non-magnetic layers, the substrate, etc., and the heat transfer rate between the layers. These speeds can be adjusted by appropriately changing the thermal conductivity, the thickness, the laminated structure, and the like of the materials constituting the layers, and thereby can correspond to a desired reproduction access speed.

It is preferable that the dielectric layer and the non-magnetic layer adjacent to the reproducing layer have a suitable heat insulating property. The degree of the heat insulating property depends on the access speed of recording / reproducing or the linear speed of recording / reproducing on the recording medium. The size and the thermal characteristics of the reproducing layer and the recording layer and the thermal characteristics in combination can be adjusted as appropriate.

In the above embodiment, the structure in which the reproducing layer of the magneto-optical recording medium is sandwiched between the dielectric layer and the non-magnetic layer has been described. May be laminated. The magnetic material has a predominant in-plane magnetic anisotropy up to its Curie temperature, and it is preferable that the Curie temperature is substantially equal to the Curie temperature of the reproducing layer. By laminating such a magnetic material in contact with the reproducing layer, it is possible to suppress the occurrence of Bloch lines in the transfer magnetic domain at the time of reproducing, and to reduce the noise at the time of reproducing by the suppression action. As a material of such a magnetic material, PTc
0 alloy, for example, PTc0 alloy containing 25 atomic% of Co or Gd
An FeCo alloy or the like can be used. The magnetic material may be laminated on the upper side or the lower side of the reproducing layer.

A light magnetic field modulation method for modulating the polarity of an applied magnetic field according to a recording signal while irradiating pulse light, and a light modulation method for modulating light intensity according to a recording signal while applying a DC magnetic field are used. Although the recording was performed, any of a magnetic field modulation recording method using a normal DC light, a light modulation recording method, and a light magnetic field modulation method may be used.

Further, the magneto-optical recording medium used in each of the above embodiments is not limited to the magneto-optical recording medium having the laminated film structure described in each of the embodiments. May be used in each embodiment.

[0097]

According to the present invention, there is provided a recording medium in which reproduction is performed by means for transferring a magnetic domain signal recorded on a magneto-optical recording film of a magneto-optical recording medium to a magnetic recording film exclusively for reproduction. Critical temperature above room temperature (Tcr2)
Up to this point, a magnetic material that transitions to perpendicular magnetization at Tcr2 or more using an in-plane magnetized film is used to transfer the recorded magnetic domain signal and to reproduce it by enlarging it. It was possible to reproduce an extremely fine recorded magnetic domain signal, which was difficult. For this reason, higher density recording has become possible.

In the present invention, an auxiliary magnetic film which has perpendicular magnetization from room temperature to a desired critical temperature between the reproducing layer magnetic film and the magneto-optical recording layer, but transitions to in-plane magnetization at a temperature higher than the critical temperature Tcr1. The magnetic signal such as an external magnetic field and a leakage magnetic field enters the reproduction signal transferred and expanded on the reproduction layer magnetized film by forming
A means for preventing shielding and a transfer magnetic field reaching the read-only magnetic recording film A magnetic film of an antiferromagnetic material is formed between the magneto-optical recording film and the read-only magnetic recording film to substantially reduce the transfer magnetic field. The means for controlling the shut-off and release of the magnetic field enables the transfer of the high-purity recording magnetic domain, thereby greatly improving the C / N of the reproduced signal.

Furthermore, since recording marks extremely small as compared with the reproducing light spot diameter can be reproduced independently, the recording density of the magneto-optical recording medium can be remarkably improved. Further, the magnetic field applied at the time of reproduction is a DC magnetic field, and it is not necessary to use an alternating magnetic field. Therefore, the reproduction operation can be performed by using a low-cost and simple reproducing apparatus.

By using this magneto-optical recording medium,
After recording a minute magnetic domain smaller than the reproduction light spot as a recording signal, the minute magnetic domain can be distinguished from other magnetic domains and detected by an amplified reproduction signal. therefore,
The magneto-optical recording medium of the present invention is extremely useful as a high-density magneto-optical recording medium.

[Brief description of the drawings]

FIGS. 1A and 1B are cross-sectional views conceptually showing a laminated structure of a magneto-optical recording medium according to the present invention.

FIG. 2 is a diagram showing magnetic temperature characteristics of a magneto-optical recording layer and a magneto-optical reproducing layer of the magneto-optical recording medium of the present invention.

FIG. 3 is a conceptual diagram (A) showing the magnetization state of each layer before reproduction of the magneto-optical recording medium of the present invention, and a conceptual diagram (B) showing the magnetization state of each layer during transfer of the magneto-optical recording medium. FIGS. 7C and 7D are conceptual diagrams (C) and (D) showing the magnetization state of each layer when the transfer magnetic domain of the magneto-optical recording medium is enlarged.

FIG. 4 is a sectional view conceptually showing another laminated structure of the magneto-optical recording medium of the present invention.

FIG. 5 is a diagram showing magnetic temperature characteristics of a magneto-optical recording layer, an auxiliary magnetic layer, and a magneto-optical reproducing layer of the magneto-optical recording medium of the present invention.

FIG. 6 is a conceptual diagram (A) showing the magnetization state of each layer before reproduction of the magneto-optical recording medium of the present invention, and a conceptual diagram (B) showing the magnetization state of each layer during transfer of the magneto-optical recording medium. FIGS. 7C and 7D are conceptual diagrams (C) and (D) showing the magnetization state of each layer when the transfer magnetic domain of the magneto-optical recording medium is enlarged.

FIG. 7 is a conceptual diagram showing a magnetization state of each layer before reproduction of the magneto-optical recording medium of the present invention.

FIG. 8 is a sectional view conceptually showing a laminated structure of the magneto-optical recording medium of the present invention.

FIG. 9 is a diagram showing the magnetic temperature characteristics of the magneto-optical recording layer, the auxiliary magnetic film, and the magneto-optical reproducing layer of the magneto-optical recording medium of the present invention.

FIG. 10 is a conceptual diagram (A) showing a magnetization state of each layer before reproduction of the magneto-optical recording medium of the present invention, and a conceptual diagram (B) showing a magnetization state of each layer during transfer of the magneto-optical recording medium. FIGS. 7C and 7D are conceptual diagrams (C) and (D) showing the magnetization state of each layer when the transfer magnetic domain of the magneto-optical recording medium is enlarged.

FIG. 11 is a sectional view conceptually showing another laminated structure of the magneto-optical recording medium of the present invention.

FIG. 12 is a sectional view conceptually showing another laminated structure of the magneto-optical recording medium of the present invention.

FIG. 13 is a sectional view conceptually showing another laminated structure of the magneto-optical recording medium of the present invention.

FIG. 14 is a conceptual diagram (A) showing the magnetization state of each layer before reproduction of the magneto-optical recording medium of the present invention, and a conceptual diagram showing the magnetization state of each layer when the transfer domain of the magneto-optical recording medium is enlarged. (B).

FIG. 15 is a conceptual diagram showing a magnetization state of each layer when a transfer magnetic domain of a magneto-optical recording medium is enlarged.

FIG. 16 is a conceptual diagram showing a magnetization state of each layer when a transfer magnetic domain of a magneto-optical recording medium is enlarged.

FIG. 17 is a sectional view conceptually showing another laminated structure of the magneto-optical recording medium of the present invention.

FIGS. 18A and 18B are conceptual diagrams (A) and (B) showing the magnetization state of each layer when the transfer magnetic domain of the magneto-optical recording medium is enlarged.

FIG. 19 is a diagram showing a temperature distribution inside a reproducing laser beam spot used for reproducing the magneto-optical recording medium of the present invention.

FIG. 20 is a conceptual diagram (A) showing the magnetization state of each layer before reproduction of the magneto-optical recording medium of the present invention, and a conceptual diagram (B) showing the magnetization state of each layer during transfer of the magneto-optical recording medium. FIGS. 7C and 7D are conceptual diagrams (C) and (D) showing the magnetization state of each layer when the transfer magnetic domain of the magneto-optical recording medium is enlarged.

FIG. 21 is a conceptual diagram (A) showing the magnetization state of each layer before reproduction of the magneto-optical recording medium of the present invention, and a conceptual diagram (B) showing the magnetization state of each layer during transfer of the magneto-optical recording medium. FIGS. 7C and 7D are conceptual diagrams (C) and (D) showing the magnetization state of each layer when the transfer magnetic domain of the magneto-optical recording medium is enlarged.

[Explanation of symbols]

 Reference Signs List 1 substrate 3 dielectric film 24 reproducing layer magnetic film 10 magneto-optical recording film 28 128 auxiliary magnetic film 30 130 magnetic film of antiferromagnetic material

Claims (19)

[Claims] 1. A magneto-optical recording medium having at least a recording magnetic film and a reproducing magnetic film on a substrate, and reproducing by irradiating a reproducing magnetic film with reproducing light. A magneto-optical recording medium comprising a laminated film in which an auxiliary magnetic film made of an antiferromagnetic material is interposed between the magnetic film and the magnetic film. 2. A magneto-optical recording medium comprising at least a recording magnetic film and a reproducing magnetic film on a substrate, and reproducing by irradiating a reproducing light to the reproducing magnetic film. It is a laminated film in which an auxiliary magnetic film made of an antiferromagnetic material whose sublattice magnetization is perpendicular to the film surface (hereinafter referred to as perpendicular magnetization) is interposed between the magnetic film and the magnetic film. Magneto-optical recording medium. 3. A magneto-optical recording medium comprising at least a recording magnetic film and a reproducing magnetic film on a substrate, and reproducing by irradiating a reproducing light to the reproducing magnetic film. The laminated film is formed by interposing an auxiliary magnetic film made of an antiferromagnetic material in which the direction of the sublattice magnetization is parallel to the film surface (hereinafter referred to as in-plane magnetization) between the magnetic film and the magnetic film. Characteristic magneto-optical recording medium. 4. An auxiliary magnetic material comprising at least the antiferromagnetic material among the recording magnetic film, the auxiliary magnetic film made of the antiferromagnetic material, and the reproducing magnetic film, according to claim 1, 2, or 3, A magneto-optical recording medium, wherein a film and the reproducing magnetic film are stacked in contact with each other. 5. The magnetic recording medium according to claim 1, wherein the auxiliary magnetic film made of the antiferromagnetic material and the reproducing magnetic film are a combination of a perpendicular magnetic magnetic film and a perpendicular magnetic magnetic film.
And a magneto-optical recording medium comprising a combination selected from a combination of an in-plane magnetization magnetic film and an in-plane magnetization magnetic film. 6. A laminated structure according to claim 1, 2 or 3, wherein a film made of a non-magnetic material is interposed between the recording magnetic film and the auxiliary magnetic film made of the antiferromagnetic material. Characteristic magneto-optical recording medium. 7. A lamination of a film made of a magnetic material and a film made of a non-magnetic material between the recording magnetic film and the auxiliary magnetic film made of the antiferromagnetic material according to claim 1, 2, or 3. A magneto-optical recording medium having a laminated structure with a body interposed therebetween. 8. The film according to claim 6, wherein the film made of the nonmagnetic material is a light reflecting film, a heat insulating film, or a heat insulating film of a magneto-optical recording medium.
A magneto-optical recording medium comprising a material selected from materials used for a dielectric film, a transparent protective film, a substrate material and the like. 9. A magneto-optical recording medium having at least a recording magnetic film and a reproducing magnetic film on a substrate, and reproducing by irradiating a reproducing light to the reproducing magnetic film, wherein the recording magnetic film and the non-magnetic A material film, a first auxiliary magnetic film which transitions to perpendicular magnetization at a temperature above the critical temperature due to in-plane magnetization at room temperature, a non-magnetic material film, an auxiliary magnetic film made of an antiferromagnetic material, and a room temperature above the critical temperature due to in-plane magnetization at room temperature A magneto-optical recording medium comprising a film layer such as a second auxiliary magnetic film functioning as a reproducing magnetic film that changes to perpendicular magnetization, and is laminated in this order. 10. A magneto-optical recording medium having at least a recording magnetic film and a reproducing magnetic film on a substrate, and reproducing by irradiating a reproducing light to the reproducing magnetic film, wherein the recording magnetic film and the non-magnetic Material film, first auxiliary magnetic film that transitions to perpendicular magnetization above critical temperature at in-plane magnetization at room temperature, non-magnetic material film, auxiliary magnetic film made of antiferromagnetic material with in-plane magnetization, at room temperature with in-plane magnetization A magneto-optical recording medium comprising: a film layer such as a second auxiliary magnetic film functioning as a reproducing magnetic film that changes to perpendicular magnetization at a critical temperature or higher, and is laminated in this order. 11. A magneto-optical recording medium having at least a recording magnetic film and a reproducing magnetic film on a substrate, and reproducing by irradiating a reproducing light to the reproducing magnetic film. Materials such as auxiliary magnetic film, non-magnetic material film, auxiliary magnetic film made of perpendicularly magnetized anti-ferromagnetic material, perpendicular magnetization reproducing magnetic film, etc. A magneto-optical recording medium comprising layers and stacked in this order. 12. A magneto-optical recording medium having at least a recording magnetic film and a reproducing magnetic film on a substrate, and reproducing by irradiating a reproducing light to the reproducing magnetic film, wherein the recording magnetic film and the non-magnetic In addition to a film layer such as a film, an auxiliary magnetic film which is perpendicularly magnetized at room temperature and transitions to in-plane magnetization at or above a critical temperature, an auxiliary magnetic film made of an antiferromagnetic material, a reproducing magnetic film, etc.
A magneto-optical recording medium characterized by being laminated in this order. 13. A magneto-optical recording medium having at least a recording magnetic film and a reproducing magnetic film on a substrate and reproducing by irradiating a reproducing light to the reproducing magnetic film, wherein the recording magnetic film and the in-plane An auxiliary magnetic film made of a magnetized antiferromagnetic material,
A magneto-optical recording medium comprising: a film layer such as a reproducing magnetic film which transitions to perpendicular magnetization at a temperature equal to or higher than a critical temperature at room temperature at room temperature, and is laminated in this order. 14. A magneto-optical recording medium having at least a recording magnetic film and a reproducing magnetic film on a substrate, and reproducing by irradiating a reproducing light to the reproducing magnetic film, wherein the recording magnetic film and An auxiliary magnetic film made of a magnetized antiferromagnetic material,
A first auxiliary magnetic film that transitions to a perpendicular magnetization above the critical temperature due to in-plane magnetization at room temperature, and a second auxiliary magnetic film that functions as a reproducing magnetic film that transitions to a perpendicular magnetization above the critical temperature due to in-plane magnetization at room temperature A magneto-optical recording medium comprising a film layer such as 15. A magneto-optical recording medium having at least a recording magnetic film and a reproducing magnetic film on a substrate, and reproducing by irradiating a reproducing magnetic film with a reproducing light, wherein the recording magnetic film has an in-plane magnetic field. An auxiliary magnetic film made of a magnetized antiferromagnetic material,
A magneto-optical recording medium comprising: a film layer such as an auxiliary magnetic film and a film for perpendicular magnetization reproduction, which transition to perpendicular magnetization at room temperature or higher at in-plane magnetization at room temperature, and are laminated in this order. 16. A magneto-optical recording medium comprising at least a recording magnetic film and a reproducing magnetic film on a substrate and reproducing by irradiating a reproducing magnetic film with reproducing light, wherein the recording magnetic film is at room temperature. A first auxiliary magnetic film which transitions to perpendicular magnetization at a temperature above the critical temperature by in-plane magnetization, a non-magnetic material film, an auxiliary magnetic film made of an antiferromagnetic material having in-plane magnetization, and A magneto-optical recording medium comprising a film layer such as a second auxiliary magnetic film functioning as a reproducing magnetic film that changes to perpendicular magnetization, and is laminated in this order. 17. A magneto-optical recording medium comprising at least a recording magnetic film and a reproducing magnetic film on a substrate, and reproducing by irradiating a reproducing magnetic film with reproducing light. From a first auxiliary magnetic film that transitions to perpendicular magnetization above the critical temperature due to in-plane magnetization, a second auxiliary magnetic film that transitions to perpendicular magnetization above the critical temperature due to in-plane magnetization at room temperature, and a perpendicular magnetization antiferromagnetic material A magneto-optical recording medium comprising: a film layer such as an auxiliary magnetic film and a magnetic film for reproducing perpendicular magnetization, and laminated in this order. 18. The magnetic recording medium according to claim 14, wherein the auxiliary magnetic film made of the antiferromagnetic material and the reproducing magnetic film are a combination of a perpendicular magnetic magnetic film and a perpendicular magnetic magnetic film, and a combination of an in-plane magnetic magnetic film and a planar magnetic film. A magneto-optical recording medium comprising a combination selected from a combination with an inner magnetization magnetic film. 19. The method of claim 9, 10, 11, 12, or 1.
6. The method according to 6, wherein the film made of the nonmagnetic material is made of a material selected from materials used for a light reflection film, a heat insulating film, a dielectric film, a transparent protective film, a substrate material, and the like of a magneto-optical recording medium. Magneto-optical recording medium.