JP2000228043A - Information recording medium, recording / reproducing method thereof, and recording / reproducing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reproducing method and a reproducing apparatus capable of reproducing with a wide reproducing power margin and a recording method and a recording apparatus suitable for ultra-high density recording. SOLUTION: A recording / reproducing apparatus 101 mainly includes a magnetic field applying device, a laser beam irradiation unit, and a signal processing system. The magnetic coil 29 provided in the magnetic field applying device is arranged such that the magnetic field generation axis 102 is oblique to the surface of the information recording medium 100. Medium 1 by laser irradiation part
While irradiating reproduction light at 00, a reproduction magnetic field is applied obliquely to the surface of the information recording medium 100 using the magnetic coil 29. Thus, the in-plane leakage magnetic field from the recording magnetic domain of the recording layer is amplified, the magnetization reversal of the reproducing layer is easily caused, and the reproducing power margin is widened. Recording / reproducing device 10
No. 1 is also capable of recording information, and can form extremely minute recording magnetic domains in the recording layer of the information recording medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium for reproducing information by transferring magnetization information of a recording layer to a reproducing layer, a recording / reproducing method thereof, and a recording / reproducing apparatus. The present invention relates to an information recording medium that can be easily formed, a method of recording and reproducing information by applying a recording magnetic field and a reproducing magnetic field by a novel magnetic field applying method, and a recording apparatus and a reproducing apparatus suitable for the method.

[0002]

2. Description of the Related Art Optical recording media such as magneto-optical recording media are known as external memories of computers and the like. Magneto-optical recording media can handle large volumes of data such as moving images and audio, and are therefore frequently used as recording media in the multimedia age. For recording on a magneto-optical recording medium,
Usually, this is performed by utilizing the temperature characteristics of the coercive force of the magnetic material constituting the recording layer. That is, a recording magnetic field in a direction opposite to the initial state is applied to a magneto-optical recording medium in which the magnetization direction of the recording layer is aligned in one direction as an initial state, and the recording layer is locally heated by irradiating the recording light. Let it. As a result, the coercive force of the heated area of the recording layer is reduced and the recording layer is reversed in the direction of the recording magnetic field. Thereafter, during the cooling process, the magnetization of the recording layer is in a stable state while being inverted, and a recording magnetic domain is formed. Thus, information is recorded on the recording layer as magnetization information.

In recent years, it has been desired to further increase the storage capacity of magneto-optical recording media. As a method for realizing this, for example, a mark edge recording method, an optical pulse magnetic field modulation recording method, and the like have been proposed.
In the mark edge recording method, information is added to a front end and a rear end of a recording mark instead of adding one piece of information to a recording mark of a recording layer. That is, this is a method in which two pieces of information are added to one recording mark to improve the recording density in the linear direction. As a result, the density can be increased by a factor of about 1.5 even when the separation limit of the reproduction light during reproduction is taken into account.

On the other hand, the optical pulse magnetic field modulation method is a method of applying a recording magnetic field having a polarity corresponding to a recording signal while irradiating a pulsed recording light in synchronization with a recording clock.
Thereby, it becomes possible to form minute recording magnetic domains in the recording layer, and the recording density is improved.

[0005]

By the way, when further increasing the density of a magneto-optical recording medium, for example, in the optical pulse magnetic field modulation system, it is considered that the control of the recording magnetic field and the recording light becomes very important. Can be That is, in order to form a minute recording magnetic domain in the recording layer, the power of the recording light that determines the size of the recording magnetic domain and the power of the recording magnetic field for inverting the recording magnetic domain must be strictly controlled. Therefore, the power margin (write power margin) of the recording light and the recording magnetic field becomes narrow. Therefore, there has been a strong demand for a new recording method capable of easily performing high-density recording.

[0006] On the other hand, a problem also arises when trying to reproduce minute recording magnetic domains formed in the recording layer. Normally, the spot diameter of the reproduction light cannot be further reduced due to the limitation of the NA of the lens mounted on the optical head.
Therefore, a plurality of minute recording magnetic domains existing in the reproducing light spot cannot be reproduced individually. That is, since the resolution of the reproduction light is insufficient, it is not possible to reproduce each minute recording magnetic domain. Therefore, it was necessary to reproduce a minute recording magnetic domain with a reproduction spot diameter of the current size.

As one method for solving this problem, for example, Journal of Magnetic Society of Japan, V
ol.17 Supplement No.S1, pp.201 (1993) proposes a magnetic super-resolution technique (MSR). With this technology, even if two recording magnetic domains exist in the reproduction light spot, it is possible to reproduce the other recording magnetic domain by masking one of the magnetic domains so as not to be visible and narrowing the effective field of view. I have to. If this technique is used, the reproduction resolution can be improved without reducing the actual reproduction light spot diameter. However, even if the magnetic super-resolution technique is used, the intensity of the reproduced signal from each magnetic domain does not change.
Remained low.

[0008] The present inventors have set forth the international publication number WO98 / 0.
No. 2878, a magnetically enlarged reproducing layer and a recording layer are provided on a substrate, and the magnetic domains transferred to the reproducing layer by applying a reproducing magnetic field while individually transferring the minute magnetic domains of the recording layer to the reproducing layer at the time of reproducing. A magneto-optical recording medium that can be reproduced on an enlarged scale has been disclosed. According to this magneto-optical recording medium, the magnetic domain transferred to the magnetically enlarged reproducing layer is enlarged to about the spot size of light, so that the intensity of the reproduced signal is significantly increased. This technology is based on MAMMOS (Magnetic A
mplifying Magneto-Optical System), which solves the problem of the above magnetic super-resolution technique relating to reproduction C / N of a minute magnetic domain.

In such MSR and MAMMOS, a reproducing magnetic field is applied perpendicularly to a medium,
The recording magnetic domain located in the high-temperature region of the recording layer heated by the irradiation of the reproduction light is transferred to the reproduction layer to read information. However, when reproducing the information recording medium on which ultra-high density recording is performed, if the magnetic field strength of the reproducing magnetic field is too strong, the recording magnetic domain does not exist in the high temperature region of the recording layer heated by irradiating the reproducing light. Nevertheless, there is a possibility that the magnetic domain of the reproducing layer is reversed in the recording direction and a reproduced signal is detected. On the other hand, if the magnetic field strength of the reproducing magnetic field is too weak, information cannot be read from the reproducing layer because the magnetic domain of the reproducing layer does not reverse in the recording direction when the recording magnetic domain exists in the high-temperature region of the recording layer. . Therefore, at the time of information reproduction, the power of the reproduction light and the reproduction magnetic field must be strictly controlled within a limited range, and there is a problem that the power margin (read power margin) of the reproduction light and the reproduction magnetic field becomes narrow. Was.

The present invention has been made to solve the above-mentioned problems of the prior art, and a first object of the present invention is to record information with a wide recording light power margin and a recording magnetic field power margin. It is to provide a recording method.

A second object of the present invention is to provide a novel recording method capable of recording information on a recording layer at a very high density.

A third object of the present invention is to provide a recording apparatus capable of easily forming minute recording magnetic domains on a recording layer of an information recording medium with high accuracy.

A fourth object of the present invention is to provide an information recording medium capable of reproducing information with a wide reproducing light power margin and a reproducing magnetic field power margin.

A fifth object of the present invention is to provide a reproducing method capable of reliably reproducing a recording magnetic domain recorded on a recording layer at a high density with an amplified reproduction signal intensity.

A sixth object of the present invention is to provide a reproducing apparatus capable of individually and reliably reproducing minute magnetic domains formed on a medium even in an information recording medium on which high-density recording is performed. is there.

[0016]

According to a first aspect of the present invention, while irradiating a recording light on a surface of a disk-shaped information recording medium having a recording layer, the information recording medium irradiated with the recording light is irradiated. In a recording method of an information recording medium for recording information by applying a recording magnetic field using a magnetic field source to a region on the medium surface, the recording magnetic field causes an in-plane component parallel to the information recording medium surface in the region. The recording magnetic field is generated from the magnetic field source in a direction oblique to the surface of the information recording medium so that the in-plane component has the same direction as the direction of the track existing in the area. Is provided.

In the recording method of the present invention, information is recorded by irradiating recording light onto the surface of the information recording medium and generating a recording magnetic field from a magnetic field source in a direction oblique to the surface of the information recording medium. At this time, the recording magnetic field is set so that the recording magnetic field has an in-plane component parallel to the medium surface in the area irradiated with the recording light, and the in-plane component is oriented in the same direction as a track existing in the area. Is generated from a magnetic field source.
According to such a recording method, it is possible to more easily reverse the magnetization of the magnetic domain of the recording layer as compared with the conventional case where the voltage is applied from the vertical direction. Therefore, the power margin of the recording light and the recording magnetic field can be widened. The reason will be described below.

According to the study of the present inventors, it has been determined that a recording magnetic field applied to an information recording medium includes a component in an in-plane direction of the recording medium (hereinafter referred to as an in-plane component of the recording magnetic field). It was found that magnetic domains could be easily formed. This is considered to be because the magnetization reversal of the recording layer is triggered by the in-plane component of the recording magnetic field as a trigger. That is, it is considered that the minute magnetic domain existing in the recording light spot of the recording layer gradually turns in the in-plane direction due to the in-plane component of the recording magnetic field when heated by the irradiation of the recording light. When a vertical component of the recording magnetic field is applied to the in-plane minute magnetic domain in the recording direction (hereinafter, the upward direction is referred to as the recording direction), the minute magnetic domain is tilted upward from the in-plane direction, and the minute magnetic domain is tilted upward. Is triggered, the magnetization in a predetermined temperature region (a region where the coercive force is reduced) in the recording light spot of the recording layer is chain-reversed to form a recording magnetic domain. These minute magnetic domains are called seed magnetic domains. At the time of recording, the magnetization reversal gradually occurs from the seed magnetic domain which is strongly receiving the in-plane magnetic field. The occurrence of the seed magnetic domain is called nucleation, and the position where the seed magnetic domain occurs in the recording layer, that is, the position where the magnetization reversal occurs first is called the nucleation point. In the present invention, since the recording magnetic field is obliquely applied to the surface of the information recording medium to include the in-plane magnetic field component, the magnetization reversal of the recording magnetic domain is easily caused. Further, when a recording magnetic field is applied to the disk-shaped medium, the direction of generation of the recording magnetic field is adjusted so that the in-plane direction of the recording magnetic field is parallel to the tangential direction of the information recording medium. New creation can be concentrated in one place. Therefore, the formation of a recording mark (recording magnetic domain) can be easily and reliably generated from one nucleation. To make the in-plane direction of the recording magnetic field parallel to the tangential direction of the information recording medium, for example,
The magnetic coil for generating the recording magnetic field may be arranged so that the direction of the component of the magnetic field generation axis projected onto the medium surface is parallel to the tangential direction of the medium. According to such a recording method, the power margins of the recording light and the recording magnetic field become wider than before.

On the other hand, when a recording magnetic field is applied only in a direction perpendicular to the medium as in the prior art, nucleation is unlikely to occur locally, and when the magnitude of the recording magnetic field exceeds a predetermined threshold value, It is considered that magnetization reversal occurs all at once in units of the magnitude. On the other hand, in the present invention, minute seed magnetic domains in the recording layer are locally generated due to the in-plane component of the recording magnetic field, and the magnetic domains are inverted in a chain triggered by the seed magnetic domains to form the recording magnetic domains. Therefore, the recording magnetic domain can be formed so as to be controllable, and a minute recording magnetic domain can be easily formed. Therefore, according to the recording method of the present invention, it is possible to form ultra-fine magnetic domains in a controlled manner, and it is possible to expect ultra-high density recording.

Japanese Patent Application Laid-Open No. 7-85526 discloses a magneto-optical recording apparatus having a magnetic field generator for applying an external magnetic field from a direction inclined with respect to the surface of a magnetic film of a magneto-optical recording medium. I have. However, this publication also describes and suggests that a magnetic field is obliquely applied so that a magnetic field generation direction is parallel to a tangential direction (track direction) of a disk-shaped medium to concentrate nucleation at one place. Not.

In the recording method of the present invention, when the recording layer of the information recording medium is a perpendicular magnetization film, the recording auxiliary layer having a perpendicular magnetic anisotropy smaller than the perpendicular magnetic anisotropy of the recording layer may be provided. preferable. The recording auxiliary layer is preferably formed so as to be in contact with one surface of the recording layer, and is laminated so as to approach the substrate in the order of the recording layer and the recording auxiliary layer, or so as to approach the substrate in the order of the recording auxiliary layer and the recording layer. May be. When the recording auxiliary layer has perpendicular magnetization during recording,
In other words, when the recording layer has perpendicular magnetization in the recording temperature range (200 ° C. to 350 ° C.), during recording, the magnetization of the recording auxiliary layer is aligned with the recording magnetic field via nucleation prior to the magnetic domain of the recording layer. Reversal occurs. As a result, the magnetization reversal of the recording magnetic domain of the recording layer is easily caused by the magnetization reversal of the recording auxiliary layer as a trigger.

On the other hand, when the recording auxiliary layer has in-plane magnetization during recording, that is, when it has in-plane magnetization in the recording temperature range, the recording auxiliary layer faces in an arbitrary direction during recording. Since the in-plane magnetization of the recording magnetic field is aligned with the direction of the in-plane component of the recording magnetic field, the inversion of the in-plane magnetization aligned in one direction of the recording auxiliary layer is likely to trigger the magnetization reversal of the recording layer.

In the present invention, examples of the material constituting the recording auxiliary layer include GdFeCo, GdFe, and GdFeCo.
dCo, GdDyFe, GdDyCo, a Gd-based alloy to which a transition metal is added, a transition metal-noble metal alloy, or a multilayer film thereof can be used. Also, CoCr
It is also possible to use an alloy containing a high melting point metal such as Ta, Pt, Mo, or the like, or a Co—Pd alloy or a granular alloy composed of a Co—Pt alloy and a nonmagnetic substance.

In the present invention, the material constituting the recording layer of the information recording medium is preferably a perpendicular magnetization film exhibiting perpendicular magnetic anisotropy at a temperature of room temperature or higher. For example, TbFeCo, DyFeCo, TbDyFeCo Most preferred are amorphous alloys of rare earths and transition metals. Further, an alternate laminate of a Pt film and a Co film, a garnet-based oxide magnetic material, or the like may be laminated on the recording layer. Also,
CoCr, a perpendicular magnetic recording material used for hard disks
A CoPt alloy film having an in-plane magnetization component may be added to the system alloy film, or a CoCr-based alloy film having an in-plane magnetization component may be added to the Pt / Co perpendicular magnetization film.

In the recording method of the present invention, in order to apply a recording magnetic field obliquely to the surface of the information recording medium,
For example, a magnetic coil for generating a recording magnetic field as conventionally used is positively tilted so that the direction of the magnetic field generated from the magnetic coil (magnetic field generation axis) is oblique to the surface of the information recording medium. What is necessary is just to apply a recording magnetic field.

According to a second aspect of the present invention, there is provided a method for recording information on an information recording medium having a recording layer by irradiating a recording light while applying a recording magnetic field. The recording medium includes a recording auxiliary layer having a perpendicular magnetic anisotropy smaller than the perpendicular magnetic anisotropy of the recording layer in contact with the recording layer, and the recording magnetic field is inclined with respect to the surface of the information recording medium. There is provided a recording method characterized in that application is performed from a direction.

In the recording method of the present invention, a recording magnetic field is applied obliquely to an information recording medium having a recording auxiliary layer in contact with the recording layer. The recording auxiliary layer is formed using a magnetic material having a smaller perpendicular magnetic anisotropy than the recording layer. Therefore, when a recording magnetic field is applied in an oblique direction, the magnetization of the recording auxiliary layer is reversed before the magnetization of the recording layer. Then, the magnetization reversal of the recording auxiliary layer triggers the magnetization of the recording layer to be easily reversed by the exchange coupling force, so that information can be recorded more easily than in the conventional case.

According to a third aspect of the present invention, there is provided a method for recording information on an information recording medium having a recording layer by irradiating a recording light while applying a recording magnetic field. A recording method is provided in which a magnetic field is applied not only in a direction perpendicular to a surface of an information recording medium but also in an in-plane direction.

In this recording method, the recording magnetic field from the in-plane direction can be made different from the intensity and application timing of the recording magnetic field from the perpendicular direction. Further, the direction of application of the in-plane recording magnetic field may be different between when recording information and when erasing information.

According to a fourth aspect of the present invention, a disk-shaped information recording medium provided with a perpendicular magnetic recording layer has a magnetic field generating axis and generates a recording magnetic field in the direction of the magnetic field generating magnetic domain. In a recording apparatus for an information recording medium comprising a device and a light source for irradiating recording light, the recording magnetic field generating device is characterized in that a magnetic field generation axis is directed obliquely to a magnetization direction of the perpendicular magnetic recording layer and a magnetic field is applied. A recording apparatus is provided, wherein a projection component of a generation axis onto a medium surface is arranged so as to face a track existing in an area irradiated with the recording light.

In the recording apparatus of the present invention, the recording magnetic field generator is arranged so that its magnetic field generation axis is parallel to the optical axis of the recording light and deviated from the optical axis of the recording light in the in-plane direction of the information recording medium. Can also. Alternatively, the recording magnetic field generator can be arranged so that the magnetic field generation axis of the recording magnetic field generator crosses the optical axis of the recording light obliquely in the information recording medium.

According to a fifth aspect of the present invention, there is provided an information recording medium comprising a perpendicular magnetic recording layer, a recording magnetic field generator for applying a recording magnetic field, and a light source for irradiating recording light. In a recording device for a recording medium, the recording magnetic field generating device generates a magnetic field in a direction perpendicular to a surface of the information recording medium, and a magnetic field in an in-plane direction with respect to the surface of the information recording medium. And a second magnetic field generating device for generating the magnetic field.

According to the recording apparatus of the present invention, a magnetic field in the in-plane direction can be generated by the second magnetic field generator.
The magnetization reversal of the recording magnetic domain of the information recording medium can be easily caused. The intensity and application timing of the magnetic field generated by the second magnetic field generating device, and when generating an alternating magnetic field, the alternating cycle does not need to be the same as that of the first magnetic field generating device.
They can be adjusted to be different from each other. When the information recording medium has a disk shape, the direction of the magnetic field generation axis of the second magnetic field generator is set so as to be parallel to the direction of the track existing in the area irradiated by the recording light. Is preferred.

In the recording apparatus of the present invention, a high NA lens having an NA (numerical aperture) of 0.5 or more, preferably 0.6 or more, is used as a lens for condensing and irradiating recording light on an information recording medium. Can be provided. More preferably,
That is, a solid immersion lens is provided. By using a solid immersion lens, the numerical aperture of the lens is effectively increased, so that the light spot diameter can be reduced. This makes it possible to record information at a very high density. When using a high NA lens and / or a solid immersion lens, it is preferable that at least one of the first and second magnetic field generators is installed below or around the high NA lens or the solid immersion lens.

According to a sixth aspect of the present invention, in an information recording medium having a recording layer and a reproducing layer, a perpendicular magnetic anisotropy smaller than the perpendicular magnetic anisotropy of the recording layer is provided between the recording layer and the reproducing layer. An information recording medium provided with a reproduction auxiliary layer having anisotropy is provided.

In the present invention, a reproduction auxiliary layer having a smaller perpendicular magnetic anisotropy than the recording layer is formed between the recording layer and the reproduction layer. As a result, the recording magnetic domain of the recording layer can be easily transferred to the reproducing layer, so that the power margin of the reproducing light and the reproducing magnetic field can be widened. The reason will be described below.

According to the study of the present inventors, in an information recording medium for reproducing information by transferring a recording magnetic domain of a recording layer to a reproducing layer, the magnetization reversal of the reproducing layer is caused by an in-plane component of a leakage magnetic field from the recording magnetic domain. Turned out to be triggered. As shown in FIG. 8A, the leakage magnetic field from the recording magnetic domain 201 of the recording layer 600 includes an in-plane component, that is, a component adjacent to the recording magnetic domain in addition to the vertical component 210 emitted in the vertical direction. Unrecorded magnetic domain (downward magnetization in the figure)
There are in-plane components 211 and 212 toward 202 and 203, respectively. Recorded magnetic domain 201 and unrecorded magnetic domain 202, 2
The minute magnetic domains 221 and 222 of the reproducing layer 300 located almost directly above the boundary with the magnetic field 03 are gradually turned in the in-plane direction by the in-plane components 211 and 212 of the leakage magnetic field when heated by the irradiation of the reproducing light. It is thought to go. When the reproducing magnetic field Hr is applied upward to the minute magnetic domains 221 and 222 facing in the plane, the minute magnetic domains 221 and 222 respectively tilt upward from the in-plane direction (FIG. 8B). By using 222 as a trigger (trigger), all the magnetic domains 213 in a predetermined area in the reproduction light spot of the reproduction layer are reversed in a chain (FIG. 8C). These minute magnetic domains 221,
Reference numeral 222 denotes a seed magnetic domain. At the time of reproduction, the magnetization reversal gradually occurs from the seed magnetic domains 221 and 222 located almost immediately above the boundary between the recorded magnetic domain 201 and the unrecorded magnetic domains 202 and 203. Therefore, if the magnetic field in the in-plane direction can be increased at the position where the magnetization reversal occurs, that is, at the nucleation point almost immediately above the boundary between the recorded magnetic domain 201 and the unrecorded magnetic domains 202 and 203, the magnetization reversal of the reproducing layer will occur. It is likely to happen easily. In the present invention, the reproduction auxiliary layer existing between the recording layer and the reproduction layer is formed using a material having a smaller perpendicular magnetic anisotropy than the recording layer. It is easy to align with the direction of the leakage magnetic field, and the leakage magnetic field in the in-plane direction from the recording magnetic domain is significantly emphasized.
In particular, if the saturation magnetization of the reproduction auxiliary layer is made larger than the saturation magnetization of the recording layer, the leakage magnetic field in the in-plane direction can be further enhanced. Therefore, the magnetization reversal of the seed domain of the reproducing layer is easily caused by the amplified in-plane component from the reproducing auxiliary layer. Therefore, the power margin of the reproducing light and the reproducing magnetic field becomes wider than before.

In the information recording medium of the present invention, in order to reproduce recorded information, it is desirable to irradiate a reproducing light and to apply a reproducing magnetic field obliquely to the medium.
When the reproducing magnetic field is obliquely applied to the information recording medium, as shown in FIG. 9, the in-plane magnetic field 311 at the nucleation point P1 increases due to the in-plane component Hx of the reproducing magnetic field, and the nucleation point P2
The magnetic field 312 in the in-plane direction at is reduced. Therefore, the magnetization reversal of the magnetic domain of the reproducing layer at the nucleation point P1 can be more easily generated. In FIG. 9, P3 exists as a nucleation point at which the in-plane magnetic field increases.
This nucleation point P3 is an unrecorded magnetic domain 3
03 is present in the reproducing spot when reproducing the same, the magnetization reversal of the reproducing layer may occur by triggering the nucleation point P3. This is caused by shifting the phase of the alternating magnetic field, that is, the magnetization reversal of the reproducing layer. This can be prevented by shifting the phase of the magnetic field (reproducing magnetic field) + Hr in the direction in which the reversal occurs to change the application timing of the reproducing magnetic field. The reproducing magnetic field may be applied not only to the information recording medium obliquely but also to two magnetic fields for applying magnetic fields in the x direction and the y direction, respectively.

In the present invention, as a material constituting the reproduction auxiliary layer, for example, GdFeCo, GdFe, GdC
o, GdDyFe, GdDyCo, a Gd-based alloy to which a transition metal is added, a transition metal noble metal alloy, or a multilayer film thereof can be used.

The information recording medium of the present invention can have a structure in which the reproduction auxiliary layer is in contact with the recording layer. A non-magnetic layer is preferably interposed between the auxiliary reproduction layer and the reproduction layer. However, a magnetic layer that becomes non-magnetic when the recording magnetic domain of the recording layer is transferred to the reproduction layer may be interposed. An information recording medium having such a structure is suitable as a magneto-optical recording medium for MAMMOS.
It can function as a layer (magnetic domain expansion reproduction layer).

Further, the information recording medium of the present invention may have a configuration in which the reproduction auxiliary layer is in contact with the reproduction layer. In this case, it is preferable to interpose a non-magnetic layer or a magnetic layer that becomes non-magnetic when the recording magnetic domain of the recording layer is transferred to the reproduction layer, between the auxiliary reproduction layer and the recording layer. An information recording medium having such a structure,
Suitable as a magneto-optical recording medium for MSR, FAD
(Front Aperture Detection)
The present invention can be applied to an AD (Rear Aperture Detection) system and a CAD (Center Aperture Detection) system.

In the present invention, the reproduction auxiliary layer has a temperature of 160 ° C.
5 em per 10 ° C. within a temperature range of ２００200 ° C.
It preferably has a temperature gradient of saturation magnetization of u / cm ³ or more. More preferably, it has a temperature gradient of a saturation magnetization of 8 emu / cm ³ or more per 10 ° C. in a temperature range of 100 ° C. to 160 ° C. In order to satisfy such a condition, for example, the compensation temperature of the material constituting the reproduction auxiliary layer may be adjusted so as to be higher than the compensation temperature of the material constituting the recording layer. In the present invention, the temperature gradient of the saturation magnetization means an average temperature gradient of the saturation magnetization in a specific temperature range.

According to a seventh aspect of the present invention, a recording layer and
In an information recording medium including a reproduction layer, the recording layer includes:
5 emu per 10 ° C. in the temperature range of 160 ° C. to 200 ° C.
/ Cm ³Features a temperature gradient of the above saturation magnetization
Is provided.

In the present invention, the recording layer is formed at 160 ° C. to 200 ° C.
5 emu / cm ³ per 10 ° C. on average over a temperature range of 10 ° C.
It is made of a material having the above-mentioned temperature gradient of saturation magnetization. More preferably, the recording layer has a temperature gradient of a saturation magnetization of 8 emu / cm ³ or more per 10 ° C. on average in a temperature range of 100 ° C. to 160 ° C. Thereby, the distribution D1 of the vertical component of the leakage magnetic field shown in FIG.
As can be seen from FIG. 6, the leakage magnetic field in the vertical direction from the recording magnetic domain M rapidly increases from the area outside the reproduction light spot S toward the center. That is, as can be seen from comparison with the conventional distribution D2 of the perpendicular component of the stray magnetic field shown in FIG. 13, the contrast of the stray magnetic field according to the temperature distribution of the recording layer in the reproducing light spot S is clearer than that of the related art. Therefore, individual minute recording magnetic domains of the recording layer are reliably transferred to the reproducing layer, and when the reproducing layer is a magnetic domain expanding reproducing layer, magnetic domain expansion easily occurs. On the other hand, when the temperature gradient of the saturation magnetization of the recording layer is adjusted, the leakage magnetic field in the in-plane direction generated from the recording magnetic domain is reduced. Therefore, even if an unrecorded magnetic domain exists in the recording layer, the unrecorded magnetic domain remains unrecorded. The magnetic domain of the reproducing layer immediately above the magnetic domain is prevented from being inverted by the reproducing magnetic field. Also in the information recording medium according to the seventh aspect of the present invention, nucleation can be easily caused by applying a reproducing magnetic field in an in-plane direction or an oblique direction and adding an in-plane component of the magnetic field. As a material for the recording layer satisfying the above conditions, for example, a heavy rare earth-transition metal alloy such as GdTbFeCo, TbFeCo, or TbDyFeCo can be used.

Further, the recording layer may have a two-layer structure composed of a first recording layer and a second recording layer.
The combined magnetization component of the saturation magnetization of the recording layer and the saturation magnetization of the second recording layer is 1 on average in the temperature range of 160 ° C to 200 ° C.
What is necessary is just to have a temperature gradient of ⁵ emu / cm ³ per 0 ° C. For example, as a second recording layer in which recording magnetic domains are formed,
When a conventional recording layer material (TbFeCo) having the temperature dependence of the saturation magnetization as shown in FIG. 10 is used, the temperature gradient of the first recording layer is steeper than the temperature gradient of the second recording layer. It is preferable to use a material having the following, for example, GdFeCo. FIG. 11 shows TbFeC
o Temperature dependence of saturation magnetization of single layer (second recording layer) and Tb
The temperature dependence of the saturation magnetization of the GdFeCo single layer (first recording layer) having a half thickness of the FeCo layer and the temperature dependence of the saturation magnetization of the composite recording film composed of them are shown.
As can be seen from the graph of FIG. 11, the conventional recording layer (TbFeCo) having a gentle temperature gradient of saturation magnetization is provided with a material (GdFeCo) having a steep temperature gradient of saturation magnetization.
With the layer structure, the temperature gradient of the saturation magnetization (synthetic saturation magnetization) can be increased in the reproduction temperature region. The value of the saturation magnetization of the composite recording layer in the graph of FIG.
This is an average value obtained by weighting the film thickness ratio between the TbFeCo layer and the GdFeCo layer.

According to the eighth aspect of the present invention, the information recording medium having the recording layer and the reproducing layer is irradiated with the reproducing light while applying the reproducing magnetic field, thereby forming the magnetic domain transferred from the recording layer to the reproducing layer. A method for reproducing an information recording medium for reproducing magnetization information, wherein the reproducing magnetic field is applied obliquely to a surface of the information recording medium is provided.

In the reproducing method of the present invention, in order to apply a reproducing magnetic field obliquely to the surface of the information recording medium,
For example, a magnetic field for generating a reproducing magnetic field, which is conventionally used, is positively arranged so that the direction of the magnetic field generated from the magnetic coil is oblique to the surface of the information recording medium, and the reproducing magnetic field is May be applied.

According to the ninth aspect of the present invention, the information recording medium having the recording layer and the reproducing layer is irradiated with the reproducing light while applying the reproducing magnetic field, thereby forming the magnetic domain transferred from the recording layer to the reproducing layer. In a reproducing method of an information recording medium for reproducing magnetization information, the reproducing method is characterized in that the reproducing magnetic field is applied not only in a direction perpendicular to the surface of the information recording medium but also in an in-plane direction. Provided.

In this reproducing method, at least one of the reproducing magnetic field applied from the vertical direction and the reproducing magnetic field applied from the in-plane direction may be an alternating magnetic field. When both the reproducing magnetic field in the vertical direction and the reproducing magnetic field in the in-plane direction are alternate magnetic fields, at least one of the magnetic field strength, the magnetic field application timing, and the alternating cycle of the alternating magnetic fields can be adjusted to be different. is there. For example, as shown in FIG. 14, an in-plane reproducing alternating magnetic field is applied so as to synchronize with a recording clock for forming a recording mark, and a vertical reproducing alternating magnetic field is applied at a half cycle of the recording clock. . At this time, the reproducing alternating magnetic field is alternated so that the in-plane component of the leakage magnetic field increases at each of the leading edge and the trailing edge of the recording mark. By synchronizing the period of the in-plane reproducing alternating magnetic field with the recording clock, it is possible to make the in-plane components of the reproducing magnetic field applied to the recording mark different from each other when detecting the leading edge and the trailing edge of the recording mark. Becomes Further, by setting the period of the reproduction alternating magnetic field in the vertical direction to half the period of the recording clock, the magnetic field in the recording direction and the erasing direction perpendicular to the film surface is applied to each of the leading edge and the trailing edge of the recording mark. This allows
A nucleation occurs at the leading edge and the trailing edge of the recording mark, and a reproduction signal can be detected from each of the leading edge and the trailing edge of one recording mark.

According to a tenth aspect of the present invention, there is provided a reproducing apparatus for an information recording medium including a reproducing magnetic field generating device for applying a reproducing magnetic field to the information recording medium including a perpendicular magnetic recording layer and a reproducing layer. The reproducing magnetic field generator is provided so as to generate a magnetic field in a direction oblique to the magnetization direction of the perpendicular magnetic recording layer.

In the reproducing apparatus of the present invention, it is preferable that the reproducing magnetic field generating apparatus is arranged so that its magnetic field generating axis generates a magnetic field in a direction oblique to the magnetization direction of the recording layer of the information recording medium. .

Also, the reproducing magnetic field generating device can be arranged at a position where the magnetic field generating axis is parallel to the optical axis of the reproducing light and deviated from the optical axis of the reproducing light in the in-plane direction of the information recording medium. . Alternatively, the magnetic field generation axis of the reproducing magnetic field generator is
It is also possible to arrange the reproducing magnetic field generator so as to obliquely cross the optical axis of the reproducing light in the information recording medium.

According to an eleventh aspect of the present invention, there is provided a reproducing apparatus for an information recording medium including a reproducing magnetic field generator for applying a reproducing magnetic field to the information recording medium including a perpendicular magnetic recording layer and a reproducing layer. A first magnetic field generating device for generating a magnetic field in a direction perpendicular to the surface of the information recording medium;
A reproducing apparatus is provided, comprising: a magnetic field generating device; and a second magnetic field generating device that generates a magnetic field in an in-plane direction with respect to the surface of the information recording medium.

In the reproducing apparatus of the present invention, a magnetic field can be generated in the in-plane direction by the second magnetic field generator, so that the magnetization reversal of the reproducing layer of the information recording medium can be easily caused. The second magnetic field generator can be configured using, for example, a single-pole type magnetic field generator (electromagnet) in which a magnetic coil is wound around a cylindrical magnetic core or a permanent magnet. When using a single-pole type magnetic field generator, the in-plane reproducing magnetic field generated by the magnetic field generator may be an alternating magnetic field or a DC magnetic field. Further, the magnetic field strength and application timing of the reproducing magnetic field generated from the second magnetic field generator, and in the case of an alternating magnetic field, the alternating cycle can be appropriately adjusted so as to be different from that of the first magnetic field generator.

In the reproducing apparatus of the present invention, a high NA lens having an NA (numerical aperture) of 0.5 or more, preferably 0.6 or more, is used as a lens for converging and irradiating the information recording medium with reproduction light. Can be provided. More preferably,
That is, a solid immersion lens is provided. By using a solid immersion lens, the numerical aperture of the lens is effectively increased, so that the light spot diameter can be reduced. This makes it possible to reproduce information recorded at a very high density. When using a high NA lens and / or a solid immersion lens, it is preferable that at least one of the first and second magnetic field generators is installed below or around the high NA lens or the solid immersion lens.

[0056]

Embodiments of the present invention will be specifically described below with reference to the drawings.

Embodiment 1 In this embodiment, a recording method and a recording apparatus of the present invention will be described.

FIG. 1 shows a sectional structure of a specific example of a magneto-optical recording medium on which information is recorded by the recording method of the present invention.
The magneto-optical recording medium 100 includes a dielectric layer 2 on a transparent substrate 1,
It has a structure in which a reproducing layer 3, a nonmagnetic layer 4, a recording auxiliary layer 5, a recording layer 6, and a protective layer 7 are sequentially laminated.

In the structure shown in FIG. 1, as the transparent substrate 1, any substrate having light transmittance can be used. For example, a substrate formed by molding a transparent resin material such as polycarbonate or amorphous polyolefin into a desired shape, or a substrate having a transparent resin film in which a desired preformat pattern is transferred onto one surface of a glass plate formed into a desired shape is used. be able to.

The dielectric layer 2 is a layer provided for causing a reproduction light beam to cause multiple interference in the layer to substantially increase the Kerr rotation angle detected from the magneto-optical recording medium. The dielectric layer 2 can be formed using a material having a higher refractive index than the transparent substrate 1, for example, an inorganic dielectric made of SiN. The protective layer 7 is a layer for protecting the film bodies 3 to 6 laminated between the transparent substrate 1 and the protective layer 7 from a chemical adverse effect such as corrosion. Become. The non-magnetic layer 4 is a layer for cutting the exchange coupling between the reproducing layer 3 and the recording auxiliary layer 5, and can be made of, for example, a non-magnetic dielectric or a non-magnetic metal.

The recording auxiliary layer 5 is a perpendicular magnetization film having a perpendicular magnetic anisotropy smaller than the perpendicular magnetic anisotropy of the recording layer 6, and can be formed using, for example, GdFeCo. The recording layer 6 is a perpendicular magnetization film exhibiting perpendicular magnetic anisotropy at a temperature equal to or higher than room temperature. For example, TbFeCo, DyFeC
o, an amorphous alloy of a rare earth and a transition metal such as TbDyFeCo is most preferable, and other known magneto-optical recording materials such as an alternate laminate of a Pt film and a Co film or a garnet-based oxide magnetic material can also be used. . The reproducing layer 3 can be formed using a magnetic material having a larger Kerr rotation angle than the material forming the recording layer 6, for example, GdFeCo.

The dielectric layer 2, the reproducing layer 3, the nonmagnetic layer 4, the recording auxiliary layer 5, the recording layer 6, and the protective layer 7 are, for example,
It can be formed by a dry process such as continuous sputtering by a magnetron sputtering apparatus.

Next, a recording / reproducing apparatus for recording information on the magneto-optical recording medium 100 will be described. In FIG.
1 shows a schematic configuration diagram of a recording / reproducing apparatus according to the present invention. The recording / reproducing apparatus 101 is controlled by the laser beam irradiating unit for irradiating the magneto-optical recording medium 100 with pulsed light at a constant cycle synchronized with the code data, and controlled by the magneto-optical recording medium 100 during recording or reproduction. It mainly comprises a magnetic field applying device for applying a recording magnetic field or a reproducing magnetic field, and a signal processing system for detecting and processing a signal from the magneto-optical recording medium 100. In the laser beam irradiating section, the laser 22 includes a laser driving circuit 32 and a recording pulse width / phase adjusting circuit (RC-PP
A) The laser drive circuit 32 is connected to a controller 51 and receives a signal from the recording pulse width / phase adjusting circuit 51 to control the laser pulse width and phase of the laser 22. The recording pulse width / phase adjusting circuit 51 receives a clock signal described later from the PLL circuit 39 and adjusts the phase and pulse width of the recording light.

In the magnetic field applying device, a magnetic coil 29 for applying a magnetic field to the medium 100 is connected to a magnetic coil driving circuit 34. The magnetic field applying device is configured such that the magnetic field generation axis 102 is inclined with respect to the surface of the magneto-optical recording medium 100 and the projected component of the magnetic field generation axis 102 on the medium surface is irradiated with laser light. Are arranged so as to be parallel to the direction of the track existing in the inside. Here, the magnetic field generation axis 102 corresponds to the central axis of the magnetic core around which the coil is wound in the magnetic coil 29. At the time of recording, a magnetic coil drive circuit (M-DRIV
E) 34 controls the magnetic coil 29 by receiving the input data from the encoder 30 to which the data is input through the phase adjusting circuit (RE-PA) 31. On the other hand, at the time of reproduction, the phase and the pulse width are adjusted through a reproduction pulse width / phase adjustment circuit (RP-PPA) 131 in response to a clock signal described later from the PLL circuit 39, and then the magnetic coil 29 is controlled. To switch the signal input to the magnetic coil drive circuit 34 between recording and reproduction, a recording / reproduction switch (RC /
(RP SW) 134 is connected to the magnetic coil drive circuit 34.

In the laser beam irradiation section, a collimator lens 2 is provided between the laser 22 and the magneto-optical recording medium 100.
3. The first polarizing prism 25 and the objective lens 24 are arranged. On the side of the prism 25, a second polarizing prism 251 and detectors 28 and 281 are arranged.
In the signal processing system, the detectors 28 and 281 are connected to a subtractor (G2) 302 and an adder (G1) 301 via I / V converters 311 and 312, respectively. The adder 301 is a clock extraction circuit (CSS) 37
Is connected to the PLL circuit 39 via the. A subtractor 302 is a sample-and-hold circuit (S / H circuit) 41 for holding a signal in synchronization with a clock, and similarly an A / D conversion circuit (A / D circuit) 42, 2 for performing analog-to-digital conversion in synchronization with a clock. It is connected to a decoder 38 via a coded signal processing circuit (BSC) 43.

In the above device configuration, the light emitted from the laser 22 is made parallel by the collimator lens 23, and is condensed on the magneto-optical recording medium 100 by the objective lens 24 through the polarizing prism 25. The reflected light from the magneto-optical recording medium 100 is directed to the polarizing prism 251 by the polarizing prism 25, passes through the half-wave plate 26, and is split into two directions by the polarizing prism 251.
The split light is condensed by a detection lens 27 and guided to photodetectors 28 and 281, respectively. Here, pits for generating a tracking error signal and a clock signal are formed on the magneto-optical recording medium 100 in advance. After the signals indicating the reflected light from the clock signal generation pits are detected by the detectors 28 and 281, the signals are extracted by the clock extraction circuit 37. Next, a data channel clock is generated in PLL circuit 39 connected to clock extraction circuit 37.

During data recording, the laser 22 is optically modulated by a laser driving circuit 32 at a constant frequency in synchronization with a data channel clock, emits a continuous pulse light having a narrow width, and rotates the rotating magneto-optical recording medium 100. Is locally heated at equal intervals. The data channel clock controls the signal processing system encoder 30 to generate a data signal having a reference clock cycle. The data signal is sent to the magnetic coil driving device 34 via the phase adjustment circuit (RE-PA) 31. Magnetic coil drive 34
Controls the magnetic field coil 29 to apply a magnetic field having a polarity corresponding to the data signal to a heated portion of the data recording area of the magneto-optical recording medium 100.

Next, a method for recording information on the magneto-optical recording medium 100 using the recording / reproducing apparatus 101 will be described in more detail.

In this embodiment, the magneto-optical recording medium 100
A description will be given of an example in which a signal is subjected to magnetic field modulation recording by applying an external magnetic field (recording magnetic field) modulated in accordance with a recording signal while irradiating a recording laser beam modulated in a pulse shape with a clock cycle. It is assumed that the magnetization direction of the recording layer of the magneto-optical recording medium 100 shown in FIG. 1 is aligned in one direction (upward in FIG. 1) in an initialized state. The magneto-optical recording medium 100 is placed on a turntable (not shown) of the recording / reproducing apparatus 101 shown in FIG. 2, and a laser beam irradiation unit is provided on the substrate 1 side, and a magnetic coil 29 is provided on the protective film 7 side.
Place. The turntable is driven by a medium drive unit (not shown) to rotate the magneto-optical recording medium 100 at a predetermined linear speed with respect to the laser beam irradiation unit and the magnetic coil 29. Next, after positioning the laser beam irradiation section and the magnetic coil 29 on a predetermined track to be recorded, a recording signal is recorded. As the recording laser light, for example, a semiconductor laser can be used.

In recording a recording signal, an external magnetic field (recording magnetic field) is applied to the magneto-optical recording medium 100 from the magnetic coil 29 by inputting the signal to a magnetic field generator in synchronization with a recording clock. Then, after the external magnetic field is switched to a predetermined value, an optical pulse modulated by the laser light irradiating unit is irradiated, and each magnetic layer of the light pulse irradiating unit of the magneto-optical recording medium 100 can be magnetization-reversed by the external magnetic field. Instantaneously heat to the temperature (recording temperature). Since the external magnetic field applied from an oblique direction to the medium includes not only the perpendicular component but also the in-plane component, nucleation occurs even in a minute area of the recording auxiliary layer heated by the recording light due to the in-plane component. Then, magnetization reversal occurs before the magnetization of the recording layer (seed magnetic domains are generated). Next, nucleation occurs in a minute area of the recording layer immediately above the seed magnetic domain generated in the recording auxiliary layer, and a seed magnetic domain is also generated in the recording layer. Then, using the seed magnetic domain of the recording layer as a trigger, the magnetization of a predetermined region formed based on the temperature distribution of the recording layer is gradually inverted by the perpendicular component of the recording magnetic field. Thereafter, the recording light spot moves from the magnetization-reversed region of the recording layer, and when the region is cooled, the magnetic domains in the region are in a stable state while being reversed. Thus, a minute recording magnetic domain is formed in the light pulse irradiation portion of the recording layer. The shape of the minute magnetic domains (recording marks) formed in the recording layer is extremely clear and has good symmetry.

In the above-mentioned signal recording of the magnetic field intensity modulation method, the laser beam is irradiated by modulating the laser beam in a pulsed manner at a constant period. It is also possible to irradiate a laser beam with continuous light at a constant intensity.

As described above, information can be recorded on the magneto-optical recording medium having the laminated structure shown in FIG. 1 by using the recording / reproducing apparatus of the present invention. When reproducing the recorded information, the medium is irradiated with reproducing light to transfer the recording magnetic domains of the recording layer to the reproducing layer, and the information is reproduced from the reproducing layer. Since the magnetic material forming the reproducing layer has a Kerr rotation angle larger than that of the recording layer, information can be reproduced with a large signal intensity.

Here, in the above magneto-optical recording medium, the MSR is formed by making the reproducing layer function as a mask layer, or by interposing a mask layer between the reproducing layer and the recording layer.
It is also possible to reproduce information by improving the reproduction resolution by (magnetic super-resolution) technology.

Further, the MAMMOS invented by the present inventors has been proposed.
Based on the principle of (Magnetic Amplifying Magneto-Optical System), the reproducing layer functions as a magnetic domain enlarging reproducing layer, so that the minute recording magnetic domain of the recording layer is transferred to the magnetic domain enlarging reproducing layer and enlarged while applying a reproducing magnetic field. be able to. Therefore, the combination of the recording method of the present invention, in which a recording magnetic field is applied obliquely to the medium, and the above-described MAMMOS, enables recording of minute recording magnetic domains in a controlled manner at a high density, This is an extremely effective combination because information can be reproduced with a high reproduction signal intensity. As for the principle of MAMMOS,
It is described in detail in International Publication No. WO 98/02878, which can be referred to.

Embodiment 2 Next, an embodiment of a magneto-optical recording medium, a reproducing method thereof, and a reproducing apparatus according to the present invention will be specifically described.

FIG. 7 shows a sectional structure of a specific example of the magneto-optical recording medium according to the present invention. The magneto-optical recording medium 200 has a structure in which a dielectric layer 2, a magnetic domain expansion reproducing layer 13, a non-magnetic layer 4, a reproduction auxiliary layer 15, a recording layer 6, and a protective layer 7 are sequentially laminated on a transparent substrate 1.

In the structure shown in FIG.
The dielectric layer 2, the non-magnetic layer 4, the recording layer 6, and the protective layer 7 are the same as the magneto-optical recording medium 100 described in the first embodiment,
A detailed description thereof will be omitted.

In FIG. 7, the magnetic domain expansion reproduction layer 13
A material used for the magnetic domain expansion reproduction layer for MMOS, for example, GdFeCo can be used. The reproduction auxiliary layer 15 is a perpendicular magnetization film having a perpendicular magnetic anisotropy smaller than that of the recording layer 6.
It can be configured using eCo.

Magnetic domain enlarged reproduction layer 13 and reproduction auxiliary layer 15
As in the first embodiment, can be formed by a dry process such as continuous sputtering using a magnetron sputtering apparatus.

As the reproducing apparatus for reproducing the information recorded on the magneto-optical recording medium 200, the recording / reproducing apparatus 101 shown in the first embodiment can be used. A method for reproducing the magneto-optical recording medium 200 using the recording / reproducing apparatus 101 will be described in more detail below.

First, the recording / reproducing apparatus 101 shown in FIG.
Then, the magneto-optical recording medium 200 is loaded so that the substrate faces down, that is, the reproduction light enters from the substrate side. It is assumed that a crescent-shaped recording magnetic domain as shown in the lower part of FIG. 12 is formed in the recording layer of the magneto-optical recording medium 200. From the recording magnetic domain having such a shape, a leakage magnetic field is generated with a magnetic field intensity as shown in the upper graph of FIG.
In the drawing, Hz indicates the magnetic field component of the leakage magnetic field generated from the recording magnetic domain in the Z direction (direction perpendicular to the paper surface), and Hx is the magnetic field component of the leakage magnetic field in the X direction, that is, the in-plane direction (lateral direction of the paper surface). The components are shown. The magnetic field distribution shown in the graph of FIG. 12 is obtained by simulation from the shape of the recording magnetic domain. The recording direction is the positive Z direction with respect to the recording magnetic domain. As can be seen from FIG. 12, the leakage magnetic field component Hx in the in-plane direction (linear direction) is about −430 [Oe] to +3.
80 [Oe] (about 33970 [A / m] to about +300
20 [A / m]). Here, the magnetic coil 29 of the reproducing apparatus 101 shown in FIG.
When the reproducing magnetic field Hr is applied so that a magnetic field of 00 [Oe] (approximately +31600 [A / m]) is applied, the in-plane component Hx of the leakage magnetic field from the recording magnetic domain becomes as shown by the broken line in the graph of FIG. , The positive direction (+ X direction) is amplified, and the negative direction (−X direction) is reduced. Then, nucleation occurs in a minute region of the reproducing layer to which the amplified in-plane leakage magnetic field Hx is applied, and a seed domain whose magnetization is reversed is generated. The seed domain whose magnetization has been inverted is expanded by the vertical component Hz of the reproducing magnetic field and spreads to the size of the reproducing light spot. Since an alternating magnetic field is used as the reproducing magnetic field, magnetic domain transfer and magnetic domain expansion are performed with a magnetic field in the + Hz direction.
It can be extinguished by a magnetic field in the Hz direction. Further, by adjusting the magnetic field generation timing in the + Hz direction of the alternating magnetic field, it is possible to concentrate the generation of the seed magnetic domains in the magnetic domain expansion reproduction layer due to the increased in-plane leakage magnetic field Hx at one location. Further, when an unrecorded magnetic domain exists in the reproducing light spot, it is possible to effectively prevent generation of seed magnetic domains in the magnetic domain enlarged reproducing layer due to the influence of the leakage magnetic field Hx from the adjacent recording magnetic domain and the vertical component Hz of the reproducing magnetic field. can do. Thus, the minute recording magnetic domains of the recording layer are transferred to the enlarged reproduction layer and enlarged. An amplified reproduction signal is obtained from the expanded magnetic domain of the expansion reproduction layer, so that the recorded information can be reproduced at a high C / N.

Embodiment 3 Next, instead of the magnetic field applying device in FIG. 2, FIG.
A perpendicular magnetic coil 15 having a magnetic field generation axis 154 in a direction perpendicular to the film surface of the magneto-optical recording medium 200 as shown in FIG.
2 and an in-plane magnetic coil 153 having a magnetic field generation axis 155 parallel to the film surface of the magneto-optical recording medium 200 and in the same direction as a track existing in the reproduction light irradiation area. A method for reproducing information will be described. As the magneto-optical recording medium 200, the same magneto-optical recording medium for MAMMOS as in the second embodiment is used. FIG.
In the magnetic field generator 151 having the configuration shown in FIG. 7, a magnetic field oblique to the film surface is applied to the magneto-optical recording medium 200 by a composite magnetic field of the magnetic field from the vertical magnetic coil 152 and the magnetic field from the in-plane magnetic coil 153. You. Both the vertical magnetic coil 152 and the in-plane magnetic coil 153 can generate an alternating magnetic field, and can independently control the magnetic field strength, the magnetic field application timing, the alternating cycle, and the like. In the present embodiment, the alternation cycle of the in-plane magnetic coil 153 is adjusted so as to synchronize with the recording clock, and the alternation cycle of the vertical magnetic coil 152 is adjusted so as to be half the recording clock.

FIG. 14 shows a recording mark sequence formed on the recording layer, a timing chart of a vertical magnetic field and an in-plane magnetic field applied when reproducing the recording mark sequence, and a reproduced waveform obtained by the timing chart. By applying the vertical magnetic field and the in-plane magnetic field at such timing, as shown in FIG. 14, a reproduced signal can be detected from the front edge and the rear edge of each recording mark. Here, when the recording mark is relatively moved with respect to the light spot, the end (edge) of the recording mark that first enters the light spot is referred to as a front edge, and the other end of the recording mark is referred to as a rear edge. Is called. In FIG. 14, the left edge of the recording mark is the front edge. In FIG. 14, the left direction in the figure is the positive direction (+ Hx) of the in-plane magnetic field. The leakage magnetic field at the front edge 403 of the shortest recording mark 401 has an in-plane component in the positive direction (+ Hx), and the leakage magnetic field at the rear edge 404 has an in-plane component in the negative direction (-Hx) (FIG. 12). In the figure, T is the period of the recording clock, and 1T shown in the figure means a recording mark formed at a period of 1T, that is, the shortest recording mark. Hereinafter, the principle of reproducing the leading edge and the trailing edge of the recording mark will be described.

As shown in the timing chart of FIG. 14, since the alternating cycle of the in-plane alternating magnetic field is synchronized with the recording clock, the surface is positioned at the front edge 403 of the recording mark formed in synchronization with the recording clock. As the inner alternating magnetic field, a magnetic field of + Hx is generated. That is, when reproducing the front edge 403, an in-plane magnetic field of + Hx in the same direction as the in-plane component of the leakage magnetic field of the front edge 403 is applied. For this reason, the in-plane component of the leakage magnetic field at the front edge 403 is amplified, and nucleation occurs in a minute region of the magnetic domain expansion reproduction layer due to the influence of the leakage magnetic field of the amplified in-plane component, and the magnetization is reversed in the magnetic domain expansion reproduction layer. A seed domain is created. Then, the seed domain whose magnetization has been inverted is expanded by a + Hz magnetic field (expanded magnetic field) generated by the vertical magnetic coil, and spreads to the size of the light spot. Next, the magnetic domain expanded by the magnetic field (erasing magnetic field) of −Hz by the vertical magnetic coil shrinks and disappears. Thus, a reproduced signal from the leading edge 403 is detected as shown in the reproduced waveform in the lower part of FIG.

Next, when reproducing the latter half of the recording mark including the trailing edge 404,
The same as the in-plane component of the stray magnetic field at the trailing edge 404-
An in-plane magnetic field of Hx is applied. As a result, the in-plane component of the leakage magnetic field in the latter half of the recording mark is amplified, and nucleation occurs in a small region of the magnetic domain expansion reproduction layer due to the amplified leakage magnetic field of the in-plane component, and the seed magnetic domain is generated in the magnetic domain expansion reproduction layer. Generated. Then, the seed domain whose magnetization has been inverted is expanded by a + Hz magnetic field (expanded magnetic field) generated by the vertical magnetic coil, and spreads to the size of the light spot. Next, the magnetic domain expanded in the magnetic domain expansion reproducing layer by the magnetic field of -Hz (erasing magnetic field) by the vertical magnetic coil is reduced and disappears. Thus, the front edge 40 of the recording mark 401
A reproduced signal is detected not only from the third part but also from the latter half of the recording mark including the trailing edge 404.

On the other hand, when reproducing the front edge 405 of the erase mark 402 having the magnetization in the opposite direction to the recording mark 401, the front edge 405 has + Hx in the direction opposite to the in-plane component of the leakage magnetic field at the front edge 405. Is applied. Therefore, seed magnetic domains are not generated in the magnetic domain expansion reproduction layer, and transfer and expansion of magnetic domains do not occur in the magnetic domain expansion reproduction layer. Therefore, no reproduced signal is detected as shown in the reproduced waveform of FIG.

The trailing edge 406 of the erase mark 402
When reproducing the latter half of the mark including, an in-plane magnetic field of −Hx in the opposite direction to the in-plane component of the leakage magnetic field at the trailing edge 406 is applied to the latter half of the erase mark. Therefore, seed magnetic domains are not generated in the magnetic domain expansion reproduction layer, and no transfer and expansion of the magnetic domains occur in the magnetic domain expansion reproduction layer, so that no reproduction signal is detected as shown in the reproduction waveform of FIG.

When reproducing the continuous recording mark, the reproduction signal is detected only from the former half of the continuous recording mark including the front edge and the latter half including the rear edge, as shown in FIG. 14, according to the same principle as described above. Is done. At this time, in portions other than the first half of the mark including the front edge of the continuous recording mark and the second half including the rear edge, for example, in the central portion of the continuous recording mark, the in-plane direction is larger than the front edge or the rear edge of the continuous recording mark. Since the leakage magnetic field is weak, even when an in-plane magnetic field is applied, nucleation does not occur in the magnetic domain expansion reproducing layer. Therefore, portions other than the first half of the mark including the front edge of the continuous recording mark and the second half including the rear edge of the continuous recording mark,
For example, no reproduction signal is detected from the center of the continuous recording mark as shown in FIG.

As described above, in the reproducing method of the present embodiment,
By changing the alternating cycle of the vertical alternating magnetic field and the in-plane alternating magnetic field, it is possible to detect the reproduced signal from the first half including the front edge of the recording mark and the second half including the rear edge, respectively. As a result, even in the case of a continuous recording mark, the reproduction signal can be reliably detected from the vicinity of the front edge and the rear edge of the continuous recording mark to know the recording mark length, so that the information can be reproduced reliably and stably. be able to.

Although the embodiments of the information recording medium, the recording method, the reproducing method and the recording / reproducing apparatus according to the present invention have been described above, the present invention is not limited to these embodiments. In the recording / reproducing apparatus described in the first embodiment, a magnetic coil in which a coil is wound around a cylindrical magnetic core is used. However, the present invention is not limited to this, and a known E-type magnetic coil or C-type magnetic coil can be used. . For example, in the case of the E-type magnetic coil 600 as shown in FIG. 3, the magnetic field generation axis 61 may be disposed so as to be directed obliquely to the surface of the magneto-optical recording medium 100.

In the above embodiment, the recording apparatus according to the fourth aspect of the present invention and the reproducing apparatus according to the tenth aspect of the present invention are constituted by the same apparatus, but only information can be recorded. It is also possible to configure as a recording device or a reproducing device that can only reproduce information.

Further, as a recording / reproducing apparatus according to the present invention,
A magnetic head 80 equipped with an SIL (Solid Immersion Lens; solid immersion lens) 80 as shown in FIG.
0 can be used. In this case, the magnetic coil 81 is provided so as to be inclined such that the magnetic field generation axis 82 of the magnetic coil 81 is oblique to the medium 100.
Alternatively, as shown in FIG. 5, a magnetic head 900 in which a magnetic coil 90 capable of generating a magnetic field in an in-plane direction is newly provided may be provided.
It is also possible to use a permanent magnet instead of zero. When a magnetic head equipped with such an SIL is used, it is necessary to make recording light incident from the side opposite to the substrate. Therefore, the recording medium, the recording auxiliary layer, the non-magnetic layer, It is desirable that the layers have a layer structure provided in this order. Further, in the above SIL, a surface other than the light entrance / exit surface is coated with a metal reflection film, and a SIM (Solid Im) that enhances near-field light by utilizing light reflection in the SIL.
mersion Mirror). The arrangement of the magnetic coils in this case may be the same as in the case of the SIL.

Further, as another modified example of the magnetic head in which recording light is incident from the side opposite to the substrate, a magnetic head 700 as shown in FIG. 6 can be used. The magnetic head 700 shown in FIG. 6 mainly includes a condenser lens 70 having an NA of 0.5 or more and a lens support plate 71 made of permalloy. The lens support plate 71 has a circular hole 72 formed therein. The recording light condensed by the condenser lens 70 is applied to the medium 100 through the hole 72. Further, a coil 73 for generating a vertical magnetic field is formed around the hole 72 by printed wiring, so that a magnetic field can be applied to the medium 100 in the vertical direction. The lens support plate 71 has holes 7.
2, a U-shaped notch is formed, and an elongated portion defined by the notch has a magnetic coil 7 for generating an in-plane magnetic field.
4 are wound. This magnetic coil 74 can generate a magnetic field in the in-plane direction. The magnetic head 700 having such a structure can also be applied to the recording / reproducing apparatus of the present invention.

Although the magneto-optical recording medium has been described as an example of the information recording medium of the present invention, the present invention is not limited thereto. For example, the present invention can be applied to magnetic recording media such as a magnetic disk having a perpendicular magnetization film on a recording layer and a magnetic disk having a pre-emboss type plastic substrate. Applicant filed Japanese Patent Application No. Hei 10-32
No. 8788, the recording layer has a Curie temperature of 3
00 ° C or higher, and within a temperature range of 10 to 100 ° C, 5
[KOe] (about 395 [kA / m]) or more, and 2 [kOe] (about 15
8 [kA / m]) discloses a thermally assisted magnetic recording medium using a perpendicular magnetization film having a coercive force of not more than 8 [kA / m].
The recording method and recording apparatus of the present invention can be applied to such a magnetic recording medium.

[0095]

According to the recording method of the present invention, since the magnetization reversal of the recording magnetic domain of the recording layer of the information recording medium can be easily generated, the power margins of the recording light and the recording magnetic field can be made wider than before. be able to. Further, since the recording magnetic domains formed in the recording layer are extremely minute, high-density recording becomes possible.

Further, since the recording device of the present invention can apply a recording magnetic field in an oblique direction to the information recording medium, minute recording magnetic domains can be individually and reliably formed on the recording layer. Therefore, it is extremely suitable as a recording device for ultra-high density recording. Further, since information can be recorded with a small magnetic field, the power consumption of the magnetic coil can be reduced. In addition, since the number of turns of the magnetic coil can be reduced, inductance is reduced, and high-speed recording and reproduction by high-speed driving can be performed.

In the information recording medium of the present invention, fine recording magnetic domains can be reliably and easily transferred to the reproducing layer, so that the power margin of the reproducing light and the reproducing magnetic field can be made wider than before. Further, since the reproduction signal can be amplified by making the reproduction layer function as a magnetic domain expansion reproduction layer, the C / N of the reproduction signal can be improved.

Further, according to the reproducing method of the present invention, only the in-plane leakage magnetic field in a predetermined direction generated from the recording magnetic domain can be amplified, and the reproduction is performed based on the in-plane leakage magnetic field in the predetermined direction and the reproducing magnetic field. The magnetization reversal of the layer can be easily generated.

Further, the reproducing apparatus of the present invention can apply a reproducing magnetic field in an oblique direction to the medium, so that minute recording magnetic domains can be individually and reliably transferred to the reproducing layer. Therefore, it is extremely suitable as a reproducing apparatus for reproducing a magneto-optical recording medium for MSR or a magneto-optical recording medium for MAMMOS on which ultra-high density recording is performed.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a cross-sectional structure of an information recording medium shown in an embodiment.

FIG. 2 is a schematic configuration diagram of a recording / reproducing apparatus according to the present invention.

FIG. 3 is a schematic view of an E-type magnetic coil capable of applying a recording magnetic field obliquely to an information recording medium.

FIG. 4 is a schematic diagram of a magnetic head equipped with an SIL (solid immersion lens) capable of applying a magnetic field obliquely to a medium.

FIG. 5 is a schematic diagram of a magnetic head including a magnetic coil and an SIL for applying a magnetic field in a vertical direction and an in-plane direction, respectively.

FIG. 6 is a specific example of a magnetic head capable of reproducing information by inputting recording light from a side opposite to a substrate;
6A is a cross-sectional view of the magnetic head, and FIG. 6B is a view of the magnetic head as viewed from the bottom.

FIG. 7 is a diagram schematically showing a cross-sectional structure of one specific example of an information recording medium according to the present invention.

FIG. 8 is a diagram illustrating a process in which the magnetization reversal of the reproducing layer occurs when a reproducing magnetic field is applied.

FIG. 9 is a diagram illustrating a state when a reproducing magnetic field having an in-plane magnetic field component is applied to a medium.

FIG. 10 shows TbFeCo used for a conventional recording layer.
6 is a graph showing temperature dependence of saturation magnetization of the present invention.

FIG. 11 shows a second structure including a GdFeCo layer and a TbFeCo layer.
5 is a graph showing the temperature dependence of the synthetic saturation magnetization of a recording layer having a layer structure.

FIG. 12 is a graph showing a magnetic field distribution of a leakage magnetic field from a crescent-shaped recording magnetic domain in an in-plane direction and a vertical direction.

FIG. 13 is a diagram showing a distribution of a vertical component of a leakage magnetic field from a recording magnetic domain formed in a recording layer.

FIG. 14 is a diagram schematically showing a record mark row recorded on a recording layer, an application timing chart of an in-plane reproducing magnetic field and a perpendicular reproducing magnetic field, and a reproduced signal obtained by the recording timing chart.

FIG. 15 schematically illustrates a configuration of a magnetic field generating apparatus including a perpendicular magnetic coil for generating a reproducing magnetic field in a direction perpendicular to a magneto-optical recording medium and an in-plane magnetic coil for generating a reproducing magnetic field in an in-plane direction. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Dielectric layer 3 Reproducing layer 4 Nonmagnetic layer 5 Recording auxiliary layer 6 Recording layer 7 Protective layer 13 Magnetic domain expansion reproducing layer 15 Reproducing auxiliary layer 80 SIL (solid immersion lens) 100, 200 Magneto-optical recording medium 101 Recording / reproducing device 61, 102 Magnetic field generation axis 700, 800, 900 Magnetic head

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 11/105 566 G11B 11/105 566D (72) Inventor Manabu Tani 1-88 Ushitora 1-chome, Ibaraki-shi, Osaka No. Hitachi Maxell Co., Ltd. (72) Inventor Masafumi Yoshihiro 1-188 Ushitora, Ibaraki City, Osaka Prefecture Hitachi Maxell Co., Ltd. (72) Hiroshi Ido 1-188 Ushitora, Ibaraki City, Osaka Hitachi Maxell, Inc.

Claims (56)

[Claims] A recording magnetic field is generated by irradiating a recording light onto a surface of a disc-shaped information recording medium having a recording layer and using a magnetic field generating source in a region on the surface of the information recording medium irradiated with the recording light. A recording method of an information recording medium for recording information by applying a magnetic field, wherein the recording magnetic field has an in-plane component parallel to the surface of the information recording medium in the area, and the in-plane component is present in the area. A recording magnetic field generated from the magnetic field source in an oblique direction with respect to the surface of the information recording medium so as to be in the same direction as the direction of the recording medium. 2. The recording method according to claim 1, wherein the recording layer is a perpendicular magnetization film, and a recording magnetic field is applied obliquely to a magnetization direction of the recording layer. 3. A magnetic coil is used as the magnetic field generating source such that the magnetic field generating axis of the magnetic coil is oblique to the surface of the information recording medium and the projected component of the magnetic field generating axis on the medium surface is oriented in the track direction. 3. The recording method according to claim 1, wherein a recording magnetic field is applied by disposing a magnetic coil in the recording medium. 4. The information recording medium further comprises a recording auxiliary layer having a perpendicular magnetic anisotropy smaller than the perpendicular magnetic anisotropy of the recording layer, wherein the recording auxiliary layer is provided in contact with the recording layer. The recording method according to claim 1, wherein: 5. The recording auxiliary layer has a temperature of 200 ° C. to 350 ° C.
5. The recording method according to claim 4, wherein the recording method has in-plane magnetization in a temperature range of: 6. The information recording medium is a magnetic recording medium using a perpendicular magnetization film having perpendicular magnetization in a recording layer, wherein the perpendicular magnetization film has a Curie temperature of 250 ° C. or higher,
The recording method according to any one of claims 1 to 5, wherein the recording method has a coercive force of 5 kOe or more in a temperature range of 10 to 100 ° C and a coercive force of 2 kOe or more at 200 ° C or more. 7. A method for recording information on an information recording medium having a recording layer by irradiating a recording light while applying a recording magnetic field, wherein the information recording medium is perpendicular to the recording layer. A recording auxiliary layer having a perpendicular magnetic anisotropy smaller than the magnetic anisotropy is provided in contact with the recording layer, and the recording magnetic field is applied obliquely to the surface of the information recording medium. Recording method. 8. The recording auxiliary layer according to claim 1, wherein the recording auxiliary layer has a temperature of 200 to 350 ° C.
8. The recording method according to claim 7, wherein the recording method has in-plane magnetization in a temperature range of: 9. The information recording medium is a magnetic recording medium using a perpendicular magnetization film having perpendicular magnetization in a recording layer, wherein the perpendicular magnetization film has a Curie temperature of 250 ° C. or higher,
The recording method according to claim 7, wherein the recording method has a coercive force of 5 kOe or more in a temperature range of 10 to 100 ° C. and a coercive force of 2 kOe or less at 200 ° C. or more. 10. A recording method for an information recording medium for recording information by irradiating a recording light to an information recording medium having a recording layer while applying a recording magnetic field, wherein the recording magnetic field is applied to a surface of the information recording medium. A recording method characterized in that the voltage is applied not only from the vertical direction but also from the in-plane direction. 11. The recording method according to claim 10, wherein the in-plane direction is a direction parallel to a plane direction of the information recording medium. 12. The recording method according to claim 10, wherein the recording layer is a perpendicular magnetization film. 13. The information recording medium further comprises a recording auxiliary layer having a perpendicular magnetic anisotropy smaller than the perpendicular magnetic anisotropy of the recording layer, wherein the recording auxiliary layer is provided in contact with the recording layer. The recording method according to claim 10, wherein the recording method is performed. 14. The recording auxiliary layer has a temperature of 200 ° C. to 350 ° C.
14. The recording method according to claim 13, having in-plane magnetization in a temperature range of ° C. 15. The information recording medium is a magnetic recording medium using a perpendicular magnetization film having perpendicular magnetization in a recording layer, wherein the perpendicular magnetization film has a Curie temperature of 250 ° C. or higher, and 10 to 100 ° C. The recording method according to any one of claims 10 to 14, wherein the recording method has a coercive force of 5 kOe or more in a temperature range of 200 kC or more and 2 kOe or less at 200 ° C or more. 16. A recording magnetic field generating device having a magnetic field generating axis and generating a recording magnetic field in the direction of the magnetic field generating domain on a disk-shaped information recording medium having a perpendicular magnetic recording layer, and irradiating a recording light. An information recording medium recording device comprising: a light source; and a recording magnetic field generation device, wherein the magnetic field generation axis is directed obliquely to the magnetization direction of the perpendicular magnetic recording layer, and the magnetic field generation axis is projected onto the medium surface. A recording apparatus, wherein components are arranged so as to face a track existing in an area irradiated with the recording light. 17. The recording device according to claim 16, wherein a recording magnetic field generated from a magnetic field generation axis of the recording magnetic field generation device is directed in a direction oblique to a magnetization direction of the recording layer. 18. The recording magnetic field generating device according to claim 1, wherein the magnetic field generating axis is arranged so as to obliquely intersect the optical axis of the recording light in the information recording medium.
18. The recording device according to 6 or 17. 19. The apparatus according to claim 16, wherein a magnetic field generation axis of the recording magnetic field generation device is parallel to an optical axis of the recording light and is shifted in an in-plane direction of the information recording medium. The recording device according to claim 1. 20. The apparatus according to claim 16, further comprising a lens for condensing the recording light and irradiating the information recording medium with the light, wherein the lens has an NA of 0.5 or more. The recording device according to claim 1. 21. The recording apparatus according to claim 20, wherein the recording magnetic field generator is provided below or around the lens. 22. A recording apparatus for an information recording medium comprising: a recording magnetic field generator for applying a recording magnetic field to an information recording medium having a perpendicular magnetic recording layer; and a light source for irradiating a recording light. A first magnetic field generator for generating a magnetic field in a direction perpendicular to the surface of the information recording medium; and a second magnetic field generator for generating a magnetic field in the in-plane direction with respect to the surface of the information recording medium. A recording device, comprising: 23. The information recording medium is disk-shaped, and a direction of a magnetic field generation axis of the second magnetic field generator is parallel to a direction of a track existing in an area of the information recording medium irradiated by the recording light. 23. The method of claim 22, wherein
The recording device according to claim 1. 24. The apparatus according to claim 22, further comprising a lens for condensing the recording light and irradiating the information recording medium with the light, wherein the lens has an NA of 0.5 or more.
The recording device according to claim 1. 25. The recording apparatus according to claim 24, wherein at least one of the first and second magnetic field generators is provided below or around the lens. 26. An information recording medium comprising a recording layer and a reproducing layer, wherein a reproducing auxiliary layer having a perpendicular magnetic anisotropy smaller than the perpendicular magnetic anisotropy of the recording layer is provided between the recording layer and the reproducing layer. An information recording medium, comprising: 27. The information recording medium is of a type in which a reproducing magnetic field is applied to the information recording medium during information reproduction, and a direction in which the reproducing magnetic field is applied is oblique to the information recording medium. Item 29. The information recording medium according to Item 26. 28. The recording medium according to claim 26, wherein the auxiliary reproduction layer is provided in contact with the recording layer.
8. The information recording medium according to 7. 29. The reproducing layer according to claim 26, wherein the reproducing layer is a magnetic domain expanded reproducing layer capable of reproducing a magnetic domain transferred from the recording layer by a reproducing magnetic field.
29. The information recording medium according to any one of 28. 30. The reproduction assist layer according to claim 26, wherein the auxiliary reproduction layer is provided in contact with the reproduction layer.
8. The information recording medium according to 7. 31. The reproduction assisting layer has a temperature of 160 ° C. to 200 ° C.
27. A temperature gradient having a saturation magnetization of ⁵ emu / cm ³ or more per 10 ° C. in a temperature range of 10 ° C.
31. The information recording medium according to any one of items 30 to 30. 32. The reproduction assisting layer has a temperature of 100 ° C. to 160 ° C.
33. A temperature gradient having a saturation magnetization of 8 emu / cm ³ or more per 10 ° C. in a temperature range of 10 ° C.
An information recording medium according to claim 1. 33. An information recording medium comprising a recording layer and a reproducing layer
In the body, the recording layer is 10 ° C. in a temperature range of 160 ° C. to 200 ° C.
5 emu / cm per ³Saturated magnetization temperature gradient
An information recording medium characterized in that: 34. The information recording medium is of a type in which a reproducing magnetic field is applied to the information recording medium at the time of reproducing information, and the application direction of the reproducing magnetic field is oblique to the information recording medium. Item 34. The information recording medium according to Item 33. 35. The information recording apparatus according to claim 33, wherein the recording layer has a temperature gradient of a saturation magnetization of 8 emu / cm ³ or more per 10 ° C. in a temperature range of 160 ° C. to 200 ° C. Medium. 36. The recording layer, comprising a first recording layer and a second recording layer, wherein the second recording layer holds magnetization information even under a reproducing magnetic field, and has a saturation magnetization of the first recording layer. The information recording medium according to any one of claims 33 to 35, wherein the temperature gradient is larger than the temperature gradient of the saturation magnetization of the second recording layer. 37. An information recording medium having a recording layer and a reproducing layer, which is irradiated with reproducing light while applying a reproducing magnetic field to reproduce magnetic information of magnetic domains transferred from the recording layer to the reproducing layer. In the reproducing method, the reproducing magnetic field is applied obliquely to the surface of the information recording medium. 38. The reproducing method according to claim 37, wherein the recording layer is a perpendicular magnetization film, and a reproducing magnetic field is applied obliquely to a magnetization direction of the recording layer. 39. A magnetic coil for generating a reproducing magnetic field, wherein the magnetic field of the magnetic coil is arranged so as to be oblique to the surface of the information recording medium and the reproducing magnetic field is applied. The reproducing method according to claim 37 or 38, wherein 40. The information recording medium, further comprising a reproduction auxiliary layer having a perpendicular magnetic anisotropy smaller than the perpendicular magnetic anisotropy of the recording layer between the recording layer and the reproducing layer. The reproduction method according to any one of claims 37 to 39. 41. An information recording medium for reproducing magnetic information of magnetic domains transferred from a recording layer to a reproduction layer by irradiating a reproduction light to an information recording medium having a recording layer and a reproduction layer while applying a reproduction magnetic field. In the reproducing method, the reproducing magnetic field is applied not only in a direction perpendicular to the surface of the information recording medium but also in an in-plane direction. 42. The reproducing method according to claim 41, wherein at least one of the vertical reproducing magnetic field and the in-plane reproducing magnetic field is an alternating magnetic field. 43. The reproducing magnetic field in the vertical direction and the reproducing magnetic field in the in-plane direction are both alternating magnetic fields, and at least one of a magnetic field intensity, a magnetic field application timing, and an alternating cycle is different. 42. The reproducing method according to 42. 44. An alternating magnetic field synchronized with a recording clock is applied from an in-plane direction, and an alternating magnetic field having a half cycle of the recording clock is applied from a vertical direction.
Reproduction method described in 1. 45. The information recording medium, further comprising, between the recording layer and the reproduction layer, a reproduction auxiliary layer having a perpendicular magnetic anisotropy smaller than the perpendicular magnetic anisotropy of the recording layer. The reproduction method according to any one of claims 41 to 44. 46. A reproducing apparatus for an information recording medium comprising: a reproducing magnetic field generator for applying a reproducing magnetic field to an information recording medium having a perpendicular magnetic recording layer and a reproducing layer; and a light source for irradiating a reproducing light. A reproducing apparatus, wherein the reproducing magnetic field generator is arranged to generate a magnetic field in a direction oblique to a magnetization direction of the perpendicular magnetic recording layer. 47. The reproducing apparatus according to claim 46, wherein the reproducing magnetic field generating apparatus is arranged so that a magnetic field generating axis is directed in a direction oblique to a magnetization direction of the recording layer. . 48. The reproducing magnetic field generator, wherein a magnetic field generating axis is parallel to an optical axis of the reproducing light and is shifted in an in-plane direction of the information recording medium. Item 50. The playback device according to Item 46. 49. The reproducing magnetic field generating device according to claim 4, wherein the magnetic field generating axis is disposed so as to obliquely intersect the optical axis of the reproducing light in the information recording medium.
7. The playback device according to 6. 50. A lens according to claim 46, further comprising a lens for condensing the reproduction light and irradiating the information recording medium with the reproduction light, wherein the lens has an NA of 0.5 or more. The playback device according to claim 1. 51. The reproducing apparatus according to claim 50, wherein the reproducing magnetic field generator is provided below or around the lens. 52. A reproducing apparatus for an information recording medium comprising a reproducing magnetic field generator for applying a reproducing magnetic field to an information recording medium comprising a perpendicular magnetic recording layer and a reproducing layer, wherein the reproducing magnetic field generator comprises: an information recording medium; A reproducing apparatus, comprising: a first magnetic field generator for generating a magnetic field in a direction perpendicular to a surface of the information recording medium; and a second magnetic field generator for generating a magnetic field in an in-plane direction to the surface of the information recording medium. . 53. The reproducing apparatus according to claim 52, wherein at least one of the first and second magnetic field generators is a magnetic field generator for generating an alternating magnetic field. 54. Both the first and second magnetic field generators are magnetic field generators for generating an alternating magnetic field, and the first and second magnetic field generators have a magnetic field intensity of the generated alternating magnetic field and a magnetic field application. 54. The reproducing apparatus according to claim 53, wherein at least one of the timing and the alternating magnetic field period is different from each other. 55. The apparatus according to claim 52, further comprising a lens for condensing the reproduction light and irradiating the information recording medium with the reproduction light, wherein the lens has an NA of 0.5 or more. The playback device according to claim 1. 56. The reproducing apparatus according to claim 55, wherein at least one of the first and second magnetic field generators is provided below or around the lens.