JPH04255946A - Magneto-optical recording and reproducing system - Google Patents

Abstract

PURPOSE:To propose a high resolution reproducing system and to make an improvement in resolution at the time of reproducing, i.e., an enhancment of S/N (C/N). CONSTITUTION:As for a magneto-optical recording medium 10 having at least a recording layer 13, a reproducing layer 11 and an intermediate layer 12 interposed between these individual layers, under the state of magnetizing one way the reproducing layer 11 excluding at least the recording layer 13 at the time of reproducing, a reproducing magnetic field Hr is given in the above magnetizing direction, and a read-out beam of light is projected, and then by this projection, at least a high temp. area 14 and a reproducible temp. area 16 are produced in a read-out light projecting area (beam spot) 6, where the intermediate layer 12 is raised in its temp. more than the Curie temp. in the high temp. area 14, and when coercive force of the layer of contribution to reproducing is denoted as HCA, and a magnetic field by a magnetic wall between the reproducing layer 11 and the intermediate layer 12 is HW1, Hr+HCA<HW1 must be proved in the reproducible temp. area 16.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magneto-optical recording and reproducing method, particularly a magneto-optical recording and reproducing method that performs super-resolution reproduction on a magneto-optical recording medium on which high-density recording has been performed. Involved. [0002] When using a magneto-optical recording and reproducing method in which information recording pits, that is, bubble magnetic domains are formed by local heating by laser beam irradiation, and this recorded information is read out by magneto-optical interaction, that is, by the Kerr effect or the Faraday effect. In order to increase the recording density of magneto-optical recording, it is necessary to make the recording pits smaller, but in this case, the resolution during reproduction becomes a problem. This resolution is determined by the wavelength of the laser during reproduction, the numerical aperture of the objective lens, and the numerical aperture of the objective lens. A. determined by A general magneto-optical recording and reproducing system will be explained with reference to FIG. FIG. 6A shows a schematic top view of a recording pattern. For example, recording pits 4 indicated by diagonal lines on land portions 2 sandwiched by grooves 1 on both sides are binary information "1" or "0". A method for reproducing a magneto-optical recording medium 3, such as a magneto-optical disk, recorded in accordance with the following will be described. Let us now consider the case where the beam spot of the readout laser beam on the magneto-optical recording medium 3 is a circular spot indicated by reference numeral 6. At this time, if the pit interval is selected so that only one recording pit 4 can exist in one beam spot 6 as shown in FIG. 6A, , there will be two modes: whether there is a recording pit 4 in the spot 6 or not. Therefore, when the recording pits 4 are arranged at equal intervals, the output waveform becomes, for example, a sine wave output whose polarity is inverted with respect to the reference level 0, as shown in FIG. 6D, for example. However, as shown in a schematic top view of a recording pattern in FIG.
comes in. For example, if we look at the three adjacent recording pits 4a, 4b, and 4c, FIGS. 7B and 7C
As shown in FIG.
Since there is no change in the reproduced output between the two cases, the reproduced output waveform becomes, for example, a straight line, as shown in FIG. 7D, and the two cannot be distinguished. As described above, in the conventional general magneto-optical recording and reproducing system, the recording pits 4 recorded on the magneto-optical recording medium 3
Even if high-density recording, that is, the formation of high-density recording pits, is possible because the data is read out in its original state, problems with S/N (C/N) arise due to resolution constraints during playback. Sufficient high-density recording and playback is not possible. Problem to be Solved by the Invention: Such S/N (C
/N), it is necessary to improve the resolution during playback, but this resolution depends on the laser wavelength,
There is a problem in that it is limited by the numerical aperture of the lens, etc. In order to solve these problems, the present applicant has previously proposed a super-resolution (super-resolution) magneto-optical recording and reproducing system (hereinafter referred to as MSR) (for example, in Japanese Patent Application No. 1-22
Application No. 5685 "Magneto-optical recording and reproducing method". [0007] To explain this MSR, this MS
In R, the recording pits 4 of the magneto-optical recording medium are generated only in a predetermined temperature range during reproduction by utilizing the temperature distribution caused by the relative movement between the magneto-optical recording medium and the beam spot 6 for reproduction. This results in higher resolution playback. [0008] Examples of this MSR system include a so-called embossed type reproduction system and a so-called annihilation type reproduction system. First, the embossed type MSR method will be explained with reference to FIG. FIG. 8A is a schematic top view showing a recording pattern of the magneto-optical recording medium 10, and FIG. 8B is a schematic cross-sectional view showing its magnetization mode. In this case, as shown in FIG. 8A, the magneto-optical recording medium 10 is moved relative to the beam spot 6 of the laser beam in the direction shown by arrow D. In this case, for example, as shown in FIG. 8B, it has at least a reproducing layer 11 made of a perpendicularly magnetized film and a recording layer 13, and more preferably an intermediate layer 12 interposed between both layers 11 and 13. A magneto-optical recording medium 10, such as a magneto-optical disk, is used. The solid line arrows in the figure schematically show the direction of the magnetic moment. In the illustrated example, the downward direction is the initial state, that is, the binary "0" or "1", and the upward direction in the figure indicates the magnetic domain due to magnetization. Information recording pits 4 are formed in at least the recording layer 13 as binary "1" or "0". [0010] In such a magneto-optical recording medium 10,
To explain the reproduction mode, first, the initializing magnetic field H is applied from outside.
i is applied to initialize the reproducing layer 11 by magnetizing it downward in the figure. That is, in the reproducing layer 11, the recording pits 4 disappear, but at this time, in the portion having the recording pits 4, the directions of magnetization of the reproducing layer 11 and the recording layer 13 are maintained in opposite directions by the magnetic domain walls generated in the intermediate layer 12. Therefore, the recording pit 4 is the latent image recording pit 4.
It remains as 1. On the other hand, an initializing magnetic field H is applied to the magneto-optical recording medium 10.
A reproducing magnetic field Hr in the opposite direction to i is applied at least to the reproducing section. In this state, as the medium 10 moves, the area having the latent image recording pits 41 that has been initialized becomes the beam spot 6.
When the temperature rises due to beam irradiation moves to the lower tip of the beam spot 6, which is to the left in FIG. 8A, the tip of the spot 5 is shown surrounded by a broken line a and shaded As a result, a high-temperature region 14 is substantially generated, the domain wall of the intermediate layer 12 disappears in this region 14, the magnetization of the recording layer 11 is transferred to the reproducing layer 13 by the exchange force, and the latent existing in the recording layer 13 is removed. The image recording pits 41 are embossed as recording pits 4 that can be reproduced on the reproduction layer 11. Therefore, if the rotation of the polarization plane of the beam spot 6 due to the Kerr effect or Faraday effect due to the direction of magnetization in the reproducing layer 11 is detected, this recording pit 4 can be detected.
can be read out. At this time, in the low temperature region 15 other than the high temperature region 14 within the beam spot 6,
The latent image recording pits 41 are not embossed on the reproducing layer 11, and there are recording pits 4 that can be read only in the narrow high temperature area 14. As a result, a plurality of recording pits 4 are formed within the beam spot 6. Even when the recording pit 4 enters the magneto-optical recording medium 10 for high-density recording, only a single recording pit 4 can be read out, and high-resolution reproduction can be performed. In order to perform such reproduction, the initialization magnetic field Hi, the reproduction magnetic field Hr, the coercive force, thickness, magnetization,
The domain wall energy, etc. is generated in the high temperature region 1 within the beam spot 6.
4 and the temperature of the low temperature region 15. That is,
Assuming that the coercive force of the reproducing layer 11 is HC1, the saturation magnetization is MS1, and the film thickness is h1, the condition for initializing only the reproducing layer 11 is the following equation 2. [Equation 2] Hi>HC1+σw2/2Ms1h1 Here, σw2 represents the domain wall energy due to the domain wall between the reproducing layer 11 and the recording layer 13. Further, the conditions for maintaining information in the recording layer 13 in the magnetic field are as follows, assuming that the coercive force of the recording layer 13 is HC3, the saturation magnetization is MS3, and the film thickness is h3. [Math. 3] Hi<HC3−σw2/2Ms3h3 00
16] Also, even after passing under the initializing magnetic field Hi, the reproducing layer 11
In order to maintain the domain wall created by the intermediate layer 12 between the recording layer 13 and the recording layer 13, the following condition 4 is required. [Formula 4] HC1>σw2/2Ms1h1 0017
At the temperature TH selected within the high temperature region 14, the following condition 5 is required. [Formula 5] HC1-σw2/2Ms1h1 <Hr <H
C1+σw2/2Ms1h1 By applying a reproducing magnetic field Hr that satisfies the equation 5,
The reproducing layer 11 is formed only in the portion where the domain wall due to the intermediate layer 12 exists.
It is possible to transfer the magnetization of the latent image recording pits 41 of the recording layer 13 to the recording layer 13, that is, to make the binary recording "1" and "0" stand out as the recording pits 4. The magneto-optical recording medium 10 used in the above-mentioned MSR method has been described as having a three-layer structure consisting of the reproducing layer 11, the intermediate layer 12, and the recording layer 13. FIG. As shown, a four-layer structure in which a reproduction auxiliary layer 17 is provided on the intermediate layer 12 side of the reproduction layer 11 can also be adopted. The reproduction auxiliary layer 17 assists the characteristics of the reproduction layer 11, thereby compensating the coercive force of the reproduction layer 11 at room temperature, and improving the reproduction layer 11 aligned by the initializing magnetic field Hi. Magnetization exists stably due to the presence of the domain wall, and the coercive force rapidly decreases near the reproduction temperature, so that the domain wall that was confined in the intermediate layer 12 spreads to the reproduction auxiliary layer 17, and finally the reproduction layer 11 is inverted to eliminate the magnetic domain walls, so that the recording pits 4 can be raised well. When a four-layer structure including the reproduction auxiliary layer 17 is adopted as described above, the coercive force HC1 of the reproduction layer 11 is replaced by HCA according to the following equation 6, and σw2/Ms
1h1 is replaced by σw2/(Ms1h1+Msshs). [Formula 6] HCA=(MS1h1 HC1+MSShS HC
S)/(MS1h1 +MSShS) (However, in the above-mentioned raised type MSR, HC1<HCA<HCS) 0
Here, MSS, hS, and HCS represent the saturation magnetization, film thickness, and coercive force of the reproduction auxiliary layer 17, respectively. Next, the annihilation type MSR will be explained with reference to FIG. FIG. 10A is a schematic top view showing a recording pattern of the magneto-optical recording medium 10, and FIG. 10B is a schematic cross-sectional view showing its magnetization mode. In FIGS. 10A and 10B, parts corresponding to those in FIGS. 8A and 8B are given the same reference numerals, and redundant explanation will be omitted. In this case, the initialization magnetic field Hi is not required. In such a magneto-optical recording medium 10,
To explain the reproduction mode, in this case, the following formula 7 is satisfied in the high temperature region 14, and as a result, even within the laser beam spot 6, the reproduction magnetic field Hr applied from the outside causes the reproduction magnetic field Hr to be applied downward in the figure. The magnetization is aligned so that the recording pits 4 in the reproducing layer 11 disappear. In other words, this annihilation type M
In the SR method, resolution is improved by making it possible to reproduce recorded pits within the low temperature region 15 of the beam spot 6. [Formula 7] Hr > HC1+σw2/2Ms1h1 0
At this time, various conditions such as coercive force are set so that the recording pits 4 remain as latent image recording pits 41 in the recording layer 13 even in the disappearing state, and at room temperature,
The magnetization of the recording layer 13, that is, the recording pits 4, are transferred to the reproduction layer 11 and held in a reproducible state. According to the above-mentioned raised type and disappearing type MSR methods, since the recorded pits in a part of the area of the reproduction laser beam spot are reproduced, the resolution at the time of reproduction can be improved. . The present invention proposes a reproduction method with even higher resolution in such an MSR reproduction method, and aims to improve the resolution during reproduction by the MSR method, that is, to improve the S/N (C/N). It is. [Means for Solving the Problems] FIG. 1A is a schematic top view showing the magneto-optical recording and reproducing system according to the present invention, FIG. 1B is a schematic cross-sectional view showing the magnetization mode, and FIG. 1C is a temperature distribution diagram. Shown below. The present invention provides at least a recording layer 1, as shown in FIG. 1B.
3, a reproduction layer 11, and an intermediate layer 1 interposed between these layers.
During reproduction, with respect to the magneto-optical recording medium 10 having the magneto-optical recording medium 10 having the magneto-optical recording medium 2, the reproduction magnetic field Hr is applied in the magnetization direction as shown in FIG. This irradiation creates at least a high temperature region 14 and a reproducible temperature region 16 in the read light irradiation region 6, and in the high temperature region 14, as shown in FIG. 1C, the intermediate layer 12 is heated to the Curie temperature Tc2 or higher, the coercive force of the layer contributing to reproduction is HCA, and the magnetic field due to the domain wall between the reproduction layer 11 and the intermediate layer 12 is HW1, then in the reproducible temperature region 16, Hr+HCA< Make sure that HW1 holds true. [Operation] The above-described magneto-optical recording method of the present invention utilizes the temperature distribution on the magneto-optical recording medium 10 that occurs due to the irradiation of read light. Assuming that the traveling direction is the direction shown by arrow D, the temperature of this magneto-optical recording medium 10 increases immediately before entering the beam spot, that is, the readout light irradiation area 6, and due to heat conduction, the temperature of this magneto-optical recording medium 10 increases until it reaches the readout light irradiation area where the irradiation intensity is strongest. A temperature distribution occurs in which the area slightly in front of the center of 6 has the highest temperature. This temperature distribution is shown in FIG. 1C. According to the above-described magneto-optical recording and reproducing method of the present invention, the reproducing layer 11 is magnetized in one direction during reproduction, and the high temperature region 14 of the magneto-optical recording medium 10 that occurs when irradiated with read light is The temperature is set to be equal to or higher than the Curie temperature Tc2 of the layer 12, and in the reproducible temperature range 16, which is a lower temperature range, the above-mentioned equation 1 is made to hold. In the high temperature region 14 on the magneto-optical recording medium 10, the magnetization of the intermediate layer 12 disappears, and the magnetization of the reproducing layer 11 becomes oriented in the same direction as the reproducing magnetic field Hr, regardless of the recording magnetization of the recording layer 13. . In the reproducible temperature region 16, the direction of magnetization of the recording layer 13 is transferred to the reproducing layer 11 in a direction opposite to the direction of the reproducing magnetic field Hr so that the above-mentioned equation 1 holds true. In a region where the temperature is lower than the reproducible temperature region 16 and Equation 1 does not hold, the magnetization of the reproducing layer 11 remains oriented in the initially aligned magnetization direction, that is, in the same direction as the reproducing magnetic field Hr. Therefore, in the magneto-optical recording medium 10 under the readout light irradiation region 6, the magnetization of the reproducing layer 11 other than the reproducible temperature region 16 is all aligned in the same direction as the reproducing magnetic field Hr, and the magnetization within the reproducible temperature region 16 is Only in the recording layer 13
The recording pits 4 of 2 are transferred to the reproduction layer 11, thereby
The “1” and “0” values in the value record can be read. [Embodiment] An example of the magneto-optical recording system of the present invention will be described below with reference to FIGS. 1 to 5. In this example, the reproduction layer 11
When using a magneto-optical recording medium 10 such as a magneto-optical disk having a four-layer magnetic layer consisting of an auxiliary layer 12a, an intermediate layer 12b and a recording layer 13, a layer that contributes to reproduction, that is, a reproduction layer 11. and the auxiliary layer 12a, the coercive force HCA is made to have the desired temperature characteristics, and in this case, further,
The Curie temperature of the auxiliary layer 12a is selected to be relatively low. This magneto-optical recording medium 10 has one main surface 21 of a light-transmitting substrate 21 made of polycarbonate PC or the like, as shown in FIG.
A dielectric film 22 made of, for example, a SiN film is deposited to a thickness of, for example, 800 Å by sputtering or the like, and the reproducing layer 11 is made of, for example, a GdFeCo-based dielectric film 22.
3(Fe85Co15)77 at 300 Å, auxiliary layer 12a
As TbFeCoAl-based Tb12 (Fe95Co5
)83Al5 etc. at 80 Å, the intermediate layer 12 is made of GdFeCo-based Gd20(Fe95Co5)80 at 150 Å, and the recording layer 13 is made of TbFeCo-based Tb2, for example.
5(Fe85Co15)75 with a thickness of 450 Å is deposited by continuous sputtering or the like. Then, a surface protection film 23 made of SiN or the like is deposited on these to a thickness of, for example, 800 Å by sputtering or the like. In this case, the Curie temperatures and coercive forces of the reproducing layer 11, auxiliary layer 12a, intermediate layer 12b, and recording layer 13 are set as shown in Table 1 below. [Table 1] A magneto-optical recording and reproducing method using such a magneto-optical recording medium 10 will be explained in detail. in this case,
As shown in a schematic perspective view in FIG. 3, the magneto-optical recording medium 10
An optical system for irradiating readout light L from the upper surface of the substrate 21 side, for example, an objective lens 24 that condenses laser light, is arranged, and this objective lens 24 is arranged with the magneto-optical recording medium 10 in between.
A reproducing magnet 25 that applies a required reproducing magnetic field Hr is placed directly below the magnetic field Hr. On the other hand, these objective lens 24 and reproduction magnet 2
An initialization magnet 26 to which an initialization magnetic field Hi is to be applied is provided at a position upstream of the track read by No. 5 and at a position that does not affect the reproduction magnetic field Hr, and the magnetic fields of the reproduction magnet 25 and the initialization magnet 26 are aligned in the same direction. At this time, the coercive force of each layer is configured as described above, and the initializing magnetic field Hi is set to 1 to 4 kOe, for example, 4 kO.
e, the reproduction layer 11 and the auxiliary layer 12a are uniformly magnetized in the direction of the initialization magnetic field Hi after passing under the initialization magnet 26, as shown in a schematic diagram of the magnetization mode in FIG. 4A. Make it possible to align. For this, [Formula 8] Hi>HCA+σW2/2(MS1h1 +MSShS
) should hold true. Here, HCA is the coercive force HC1 of the reproducing layer 11 and the coercive force HCS of the auxiliary layer 12a.
The above-mentioned HCA=(MS1
h1 HC1+MSShS HCS)/(MS1h1
+MSShS). Here, MS1 and MSS are the reproduction layer 11 and the auxiliary layer 1, respectively.
The saturation magnetization of 2a, h1 and hS are the reproduction layer 11, respectively.
, the thickness of the auxiliary layer 12a. Also, in equation 8, σW2
is the domain wall energy of the intermediate layer 12b. Equation 8 above corresponds to conditional expression Equation 2 in the MSR regeneration method described above. On the other hand, the recording layer 13 has a large coercive force so that its magnetization direction is maintained in the direction set during recording. For this purpose, it is sufficient that Hi<HC3-σW2/2MS3h3. Here, HC3 is the coercive force of the recording layer 13, MS3 is the saturation magnetization of the recording layer 13, and h3 is the thickness of the recording layer 13. This condition corresponds to Equation 3 above. Further, in order to maintain the direction of magnetization of the recording layer 13 and the direction of magnetization of the initialized reproduction layer 11 and auxiliary layer 12a opposite to each other in the absence of a magnetic field, the following formula is used:
It is sufficient if HCA>σW2/2 (MS1h1 +MSShS). This corresponds to Equation 4 above. A reproducing magnetic field Hr is applied in the same direction as the initializing magnetic field Hi under the readout light irradiation region 6 by the readout light. As the magneto-optical recording medium 10 moves in the direction indicated by the arrow D as shown in FIG. The temperature is highest at the front,
A temperature distribution occurs with this as the peak. This high temperature area 14
As shown in FIG. 4B, the readout light irradiation area 6 is a region that is biased to the left in the diagram, and in this region 14, the temperature is raised to the Curie temperature Tc2 or higher of the intermediate layer. In the example, the auxiliary layer 12a whose Curie temperature Tc2 is 140° C. is heated above the Curie point and its magnetization disappears. Therefore, the magnetization of the reproducing layer 11 is aligned in the direction of the reproducing magnetic field Hr. The regenerator temperature region 16 having a temperature lower than the high temperature region 14 is an arc-shaped region sandwiched between the high temperature region 14 and the low temperature region 15. This temperature region 16 is shown in FIG.
As shown by hatching C, in a region where the Curie temperature TC2 of the auxiliary layer 12a is lower than the predetermined temperature TB, Hr+HCA<HW1 is satisfied in this region. Here, HCA is determined by Equation 6 above. In this way, the reproducing magnetic field Hr and the reproducing layer 11
When the magnetic field HW1 due to the domain wall generated between the intermediate layer 12b and the intermediate layer 12b is made larger than the sum of the average coercive force HCA of the auxiliary layer 12a, the magnetization of the reproducing layer 11 and the auxiliary layer 12a resists the reproducing magnetic field Hr. It is aligned parallel to the direction of magnetization of the recording layer 13. That is, when there is recording magnetization in the recording layer 13 in a direction opposite to the direction of the reproducing magnetic field Hr, that magnetization is transferred to the reproducing layer 11. In this case, a temperature region lower than the reproducible temperature region 16, ie, less than the above-mentioned TB, occurs in a crescent shape within the readout light irradiation region 6, but in this low temperature region 15, Equation 1 does not hold. Therefore, the magnetization of the reproducing layer 11 is maintained uniformly oriented in the direction aligned by the initialization magnetic field Hi, which is the same as the magnetization direction of the reproducing layer 11 within the high temperature region 14. Therefore, within the readout light irradiation area 6, the high temperature area 14 and the low temperature area 15
As shown in FIGS. 4A and 4B, the lower recording pits are retained in the recording layer 13 as latent image pits 27, but are retained in the reproduction layer 11.
The recording pits 4 are not transferred to the reproducing layer 11, but are transferred to the reproducing layer 11 only in a narrow region of the reproducible temperature region 16. In this case, as described above, the reproducible temperature region 16 is a narrow region sandwiched between the high temperature region 14 and the low temperature region 15, so even if higher density recording is performed, it is possible to reproduce the data with high resolution. becomes possible. FIG. 5 shows the output characteristics when using the magneto-optical recording medium 10 having such a four-layer structure. In the figure, a solid line C represents a signal output, and a broken line N represents a noise output. In this example, the initialization magnetic field is 4k [Oe], the output of the readout light L is 3.3mW, and the magneto-optical recording medium 10 is heated at 2400 rpm.
pm, and the distance r from the center of the magneto-optical recording medium 10
This shows the case where a single frequency of 10 MHz was recorded on a track of 30 mm. At this time, the average coercive force HCA of the reproduction layer 11 and the auxiliary layer 12a is 4k [Oe], and the intermediate layer 1
The coercive force of 2b is 1 k [Oe], and the coercive force of the recording layer 13 is 1
A 5k [Oe] magneto-optical recording medium 10 was used. As can be seen from FIG. 5, according to the magneto-optical recording and reproducing method of the present invention, 1
Even in high frequency recording of 0MHz, the reproduction magnetic field Hr,
So that the difference between line C and line N is large, i.e. 30 in this case
Good C/C/
A high N ratio can be obtained, and high-density recording can be reproduced with high resolution. Note that in the above example, the initialization magnet 26
is provided upstream of the position where the magneto-optical recording medium 10 is read, but even if this initialization magnet 26 is not provided,
Immediately after recording or just before reproduction, a magnetic field having the same direction and magnitude as the reproduction magnetic field Hr is applied to the magneto-optical recording medium 1 by the reproduction magnet 25.
By applying 0, the magnetization of the reproducing layer 11 can be aligned in one direction, and then high-resolution reading can be performed by the method described above. Furthermore, the present invention is not limited to the above-mentioned example, and can be applied to magneto-optical recording media having various other configurations. That is, the present invention can also be applied to a magneto-optical recording medium having a three-layer structure of the reproducing layer 11, the intermediate layer 12, and the recording layer 13 without providing the auxiliary layer 12a. In this case, for example, as the reproduction layer 11, Gd24(Fe85Co15) 76
For example, using Tb18Fe82 as the intermediate layer 12 and Tb25 (Fe85Co15) 75 as the recording layer 13, and replacing the coercive force HCA of the layer contributing to reproduction in Equation 1 with the coercive force HC1 of the reproducing layer 11, Equation 1 holds. Also, the above-mentioned number 6 is replaced with the above-mentioned number 2, number 9 is replaced with number 3, and number 10 is replaced with number 4, and the coercive force and film thickness of each layer,
Select magnetization and domain wall energy. By making this selection, high-resolution reproduction as described above can be performed even in a magneto-optical recording medium consisting of a three-layered magnetic layer. As described above, according to the magneto-optical recording and reproducing system of the present invention, since the readable area in the readout light irradiation area 6 is sandwiched between the high temperature area 14 and the low temperature area 15, Compared to the above-mentioned MSR reproduction method, the readable area is further narrowed, and more recording pits 4 are present in the readout light irradiation area 6 in the magneto-optical recording medium 10 with high recording density. can be reliably read. Furthermore, when increasing the reproduction output by increasing the reproduction laser output, a sufficiently high resolution can be maintained even when the spot diameter, that is, the area of the readout light irradiation area 6 becomes large, and C/N ( This makes it possible to improve the signal-to-noise ratio (S/N) and perform high-resolution reproduction exceeding the conventional reproduction resolution limit. [0047] In particular, if the magnetization of the reproducing layer is aligned in one direction immediately before reproducing using the reproducing magnetic field generating means without providing the initializing magnetic field generating means, the apparatus can be simplified.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of the magneto-optical recording and reproducing method of the present invention.

FIG. 2 is a schematic enlarged cross-sectional view of a main part of an example of the magneto-optical recording medium of the present invention.

FIG. 3 is a schematic perspective view showing the magneto-optical recording and reproducing system of the present invention.

FIG. 4 is an explanatory diagram showing an example of the magneto-optical recording and reproducing method of the present invention.

FIG. 5 is an output characteristic diagram of a magneto-optical recording medium using the magneto-optical recording and reproducing method of the present invention.

FIG. 6 is an explanatory diagram showing a conventional magneto-optical recording and reproducing method.

FIG. 7 is an explanatory diagram showing a conventional magneto-optical recording and reproducing method.

FIG. 8 is an explanatory diagram of an embossed MSR method.

FIG. 9 is a schematic cross-sectional view of a magneto-optical recording medium.

FIG. 10 is an explanatory diagram of the annihilation type MSR method.

[Explanation of symbols]

4 Record pit 6 Readout light irradiation area 10 Magneto-optical recording medium 11 Reproduction layer 12 Middle class 12a Auxiliary layer 12b Middle class 13 Recording layer 14 High temperature area 15 Low temperature region 16 Renewable temperature range 21　Substrate 22 Dielectric layer 23　Surface protective film

Claims (1)

[Claims] Claim 1: For a magneto-optical recording medium having at least a recording layer, a reproduction layer, and an intermediate layer interposed between these layers, during reproduction, the reproduction layer, except for at least the recording layer, is magnetized in one direction. In this state, a readout magnetic field Hr is applied to the magnetization direction and readout light is irradiated, and by this irradiation, at least a high temperature region and a reproducible temperature region are generated in the readout light irradiation region, and in the high temperature region, the above intermediate temperature region is generated. When the layer is heated to a temperature higher than the Curie temperature, the coercive force of the layer that contributes to reproduction is HCA, and the magnetic field due to the domain wall between the reproduction layer and the intermediate layer is HW1, in the reproduction temperature range, [Equation 1] ] A magneto-optical recording and reproducing system characterized in that Hr+HCA<HW1 holds true.