JP2778526B2 - Magneto-optical recording medium and its recording / reproducing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical recording medium and a method for recording and reproducing the same, and more particularly to a magneto-optical recording medium suitable for high-density recording and a method for recording and reproducing the same.

[0002]

2. Description of the Related Art A magneto-optical recording medium is a magnetic film for magneto-optical recording formed on a substrate made of a synthetic resin such as glass or polycarbonate by a method such as a sputtering method. Information is recorded using the thermomagnetic effect accompanying the temperature rise. More specifically, a magnetic film having perpendicular magnetic anisotropy is used. When a laser beam having a diameter of, for example, 1 μm or less is applied while applying a constant magnetic field from the outside, the laser beam is applied. When the part is heated and reaches a certain temperature or higher, the magnetization of the irradiated part is reversed. Therefore, information is set to 0, 1 depending on whether the magnetization is upward or downward.
Is recorded as a binary signal.

On the other hand, recorded information is reproduced by injecting a linearly polarized laser beam into a magneto-optical recording medium and reflecting light from the optical recording medium by rotating the plane of polarization by the magnetic Kerr effect.
Alternatively, light transmitted through the magneto-optical recording medium is captured by rotation of the plane of polarization due to the magnetic Faraday effect. For example, when utilizing the magnetic Kerr effect, the reflected light is used as a photodetector by utilizing the fact that the rotation angle of the plane of polarization of reflected light (hereinafter referred to as “Kerr rotation angle”) differs depending on the direction of recording magnetization. Before entering, the information corresponding to the direction of magnetization is read out as a change in the amount of light through an analyzer.

By the way, in recent years, for the purpose of increasing the capacity of recorded information, a narrower track is required for producing a high-density recording magneto-optical medium (magneto-optical recording is performed along a track, so that the track width is reduced as much as possible). , Shortening of reading laser wavelength, PRML (Partial Response Maximum Likelih)
ood) and other advanced signal processing technologies are being actively developed.

[0005] However, narrowing the track is approaching the limit of mastering (technique for forming a substrate), and it is becoming difficult to form a good track. In addition, as the track becomes narrower, formation of prepits (holes formed in advance on a substrate for reading address information on a magneto-optical recording medium) becomes more difficult. On the other hand, attempts to increase the spatial resolution by reducing the focusing diameter of the laser beam by shortening the wavelength of the readout laser are promising, but semiconductor lasers with wavelengths shorter than green are still in the research stage and are not yet ready for practical use. take time. Further, as the read laser wavelength becomes shorter, the Kerr rotation angle of the magneto-optical recording medium decreases, and a problem arises in that good C / N cannot be obtained. PRML is also a powerful means, but has the disadvantage of increasing drive costs.

[0006]

The major drawbacks of these technologies are that data recording / reproducing on a magneto-optical recording medium is performed only two-dimensionally.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has as its object to provide a high-performance recording / reproducing apparatus capable of three-dimensionally recording and reproducing information and capable of being easily manufactured using conventional substrate manufacturing techniques. An object of the present invention is to provide a density magneto-optical recording medium and a recording / reproducing method thereof.

[0008]

In order to achieve the above object, a magneto-optical recording medium according to the present invention comprises a magnetic film having at least first, second and third magnetic perpendicular anisotropies in order from the light irradiation side. And the respective Curie temperatures Tc1, Tc2 and Tc3 of the first, second and third magnetic films are Tc2 <
The first magnetic film satisfies the relationship of Tc1 <Tc3, and the first magnetic film is so small that the Kerr rotation angle does not contribute to recording and reproduction. When the magnetization state of the first magnetic film is lower than Tc2, the second magnetic film always becomes the second magnetic film. The second magnetic film and the third magnetic film are transferred to a magnetic film, and satisfy a relationship in which the magnetization state is not transferred to each other.

In the magneto-optical recording medium, the temperature of the magneto-optical recording medium is raised to a temperature higher than the Curie temperature of the third magnetic film, and recording is performed on the third magnetic film. Recording on the first and second magnetic films by increasing the temperature of the magneto-optical recording medium to a temperature range from the Curie temperature of the magnetic film to the Curie temperature of the third magnetic film.

Further, the magneto-optical recording medium may include
Raising the temperature of the magneto-optical recording medium to a temperature range from the Curie temperature of the magnetic film to the Curie temperature of the first magnetic film to reproduce the signal recorded on the third magnetic film, The signal recorded on the second magnetic film is reproduced by raising the temperature of the magneto-optical recording medium to a temperature lower than the Curie temperature of the second magnetic film.

[0011]

According to the present invention, different information can be recorded on the first and second magnetic films and the third magnetic film, respectively, and three-dimensional recording, that is, multi-layer recording can be realized.

[0012]

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

FIG. 1 is a sectional view showing the structure of the magneto-optical recording medium according to the present embodiment. The magneto-optical recording medium 10 has an interference film 4 as a dielectric film and a magnetic film 1 as a recording film on a substrate 6.
A magnetic film 2 and a magnetic film 3, and a protective film 5 as a dielectric film are sequentially formed, and a laser is irradiated to record data on the magneto-optical recording medium 10 and reproduce the recorded data. The light spot 7 of light is emitted from the substrate 6 side. Therefore, in FIG. 1, the magneto-optical recording medium 10 is shown in a sectional view with the substrate 6 on the light irradiation side facing upward.

Next, the recording film characteristics of the magnetic films 1, 2, and 3 will be described. The recording film characteristics such as Curie temperature, coercive force, and Kerr rotation angle described below can be controlled by adjusting the composition of the magnetic film.

Assuming that the Curie temperatures of the magnetic films 1, 2, and 3 in this embodiment are Tc1, Tc2, and Tc3, respectively, the magnetic films 1 and 2 have a relationship of Tc2 <Tc1 <Tc3. -3 are adjusted.
The composition of the magnetic film 1 is adjusted so that the Kerr rotation angle has a small value that does not contribute to reproduction.

Further, in the magnetic films 1, 2, and 3, the magnetic film 1
Is transferred to the magnetic film 2, but the magnetization state of the magnetic film 2 is not transferred to the magnetic film 3.

Here, the relationship between the transfer of the magnetization states of the magnetic films 1 to 3 will be described in more detail. The relationship between the magnetic film 1 and the magnetic film 2 or the relationship between the magnetic film 2 and the magnetic film 3 is exchangeable. This can be explained based on the basic principle of a two-layer bonding film. The exchange coupling two-layer film refers to a film in which when two magnetic films are stacked, the magnetic moments of the two films exert a magnetic exchange interaction with each other through an interface.

Now, the interface domain wall energy density acting between the magnetic film 1 and the magnetic film 2 is σ1, the interface domain wall energy density acting between the magnetic film 2 and the magnetic film 3 is σ2,
Two or three magnetizations are respectively Ms1, Ms2, Ms3, magnetic film 1,
Assuming that the coercive forces 2 and 3 are Hc1, Hc2 and Hc3, and the thicknesses of the magnetic films 1, 2 and 3 are h1, h2 and h3, respectively, the exchange force that the magnetic film 2 receives from the magnetic film 1 is σ1 /
(2 × Ms2 × h2), the exchange force that the magnetic film 2 receives from the magnetic film 3 is σ2 / (2 × Ms2 × h2), and the exchange force that the magnetic film 3 receives from the magnetic film 2 is σ2 / (2 × Ms3
× h3).

Therefore, the coercive force Hc2 of the magnetic film 2 is
If the exchange force σ1 / (2 × Ms2 × h2) that the magnetic film 2 receives from the magnetic film 1 is larger than the coercive force Hc2 of the magnetic film 2, the magnetization state of the magnetic film 1 Is changed, the changed magnetization state is always transferred to the magnetic film 2 at room temperature.

The relationship between the magnetic films 1 and 2 is shown in FIG.
It can be represented by the graph of FIG. 3A and the Kerr loop of FIG.

FIG. 3A is a graph showing the relationship between the coercive force of the magnetic film 1 and the magnetic film 2 and the temperature, wherein the ordinate represents the coercive force and the abscissa represents the temperature. As shown in FIG. 3A, the coercive force of the magnetic film 2 is always smaller than the coercive force of the magnetic film, and the Curie temperature of the magnetic film 1 is higher than the Curie temperature of the magnetic film 2.

FIG. 3B shows the relationship between the applied magnetic field of the magnetic film 1 and the magnetic film 2 and the Kerr effect when a magnetic field is applied to the exchange-coupling two-layer film formed by the magnetic film 1 and the magnetic film 2. It is a car loop showing the relationship. The vertical axis of the car loop has a magnetic film 1,
The amount proportional to the Kerr effect of the reflected laser light applied to 2 is shown on an arbitrary scale, and the horizontal axis shows the applied magnetic field on the arbitrary scale. The relationship between the exchange force and the coercive force can be understood from this Kerr loop. That is, in FIG. 3B, the Kerr loop of the magnetic film 2 is a minor loop (a Kerr loop measured without applying an applied magnetic field up to the reversal magnetic field of the magnetic film 1), and the Kerr loop of the magnetic film 2 has an applied magnetic field of zero (the center of the applied magnetic field). Since the loop is drawn in the region above the vertical line, it can be understood that the exchange force is larger than the coercive force in the magnetic film 2 (the reversal magnetic field means that the loop is from bottom to top or from top to bottom). The value of the moving applied magnetic field).

On the other hand, since the exchange force which the magnetic film 3 receives from the magnetic film 2 is σ2 / (2 × Ms3 × h3), the magnetic film 3
Is smaller than the coercive force Hc2 of the magnetic film 2, the exchange force σ2 / (2 ×
If Ms3 × h3) is smaller than the coercive force Hc3 of the magnetic film 3,
The magnetization state of the magnetic film 2 is not transferred to the magnetic film 3. Further, the coercive force Hc3 of the magnetic film 3 is equal to the coercive force Hc of the magnetic film 2.
When c2 is larger than c2, the exchange force σ2 / (2 × Ms2 × h2) received by the magnetic film 2 from the magnetic film 3 is equal to the coercive force Hc2 of the magnetic film 2.
If it is smaller, the magnetization state of the magnetic film 3 will not be transferred to the magnetic film 2.

The relationship between the magnetic films 2 and 3 is shown in FIG.
It can be represented by the graph of (c) and the Kerr loop of FIGS. 3 (d) and 3 (e).

FIG. 3C is a graph showing the relationship between the coercive force of the magnetic film 2 and the magnetic film 3 and the temperature, wherein the ordinate represents the coercive force and the abscissa represents the temperature. As shown in FIG. 3C, the coercive force of the magnetic film 2 is larger than the coercive force of the magnetic film 3 in the temperature region indicated by A, and smaller than the coercive force of the magnetic film 3 in the temperature region indicated by B. The Curie temperature of the magnetic film 2 is lower than the Curie temperature of the magnetic film 3.

FIGS. 3D and 3E show the magnetic field applied to the magnetic film 2 and the magnetic film 3 when a magnetic field is applied to the exchange-coupled two-layer film formed by the magnetic film 2 and the magnetic film 3. It is a car loop showing the relationship with the Kerr effect. The vertical axis of the Kerr loop indicates the amount of reflected light of the laser light applied to the magnetic films 1 and 2 in proportion to the Kerr effect on an arbitrary scale, and the abscissa indicates the applied magnetic field on an arbitrary scale. 3D is a Kerr loop in the temperature region indicated by A in FIG. 3C, and FIG. 3E is B in FIG. 3C.
Shows a Kerr loop in the temperature range indicated by. The relationship between the exchange force and the coercive force can be understood from these Kerr loops. That is, in FIG. 3D, the Kerr loop of the magnetic film 3 is a minor loop (a Kerr loop measured without applying an applied magnetic field up to the reversal magnetic field of the magnetic film 2), and the Kerr loop of the magnetic film 3 has an applied magnetic field of zero (the center of the applied magnetic field). Since the loop is drawn across the vertical line), it can be understood that the exchange force received from the magnetic film 2 in the magnetic film 3 is smaller than its own coercive force. In FIG. 3E, the Kerr loop of the magnetic film 2 is a minor loop (a Kerr loop measured without applying an applied magnetic field up to the reversal magnetic field of the magnetic film 3), and when the Kerr loop of the magnetic film 2 has no applied magnetic field ( Since the loop is drawn across the central vertical line, it can be seen that the exchange force received from the magnetic film 3 in the magnetic film 2 is smaller than its own coercive force.

The schematic diagram of the Kerr loop shown in FIG. 3 shows a case where only the magnetic film 1 and the magnetic film 2 are formed and a case where only the magnetic film 2 and the magnetic film 3 are formed. When three films are actually formed, it becomes more complicated. In FIG. 3C, there is also a temperature region where the coercive force of the magnetic film 3 is smaller than the coercive force of the magnetic film 2, but the coercive force of the magnetic film 3 is between room temperature and the Curie temperature of the magnetic film 3. Naturally, the coercive force of other magnetic films may be larger than that of other magnetic films.

Next, a recording / reproducing method for a magneto-optical recording medium according to the present invention will be described with reference to FIG. FIG.
2D is a diagram illustrating a method for recording information on the magneto-optical recording medium according to the present embodiment, and FIGS. 2E to 2G are methods for reproducing information recorded on the magneto-optical recording medium according to the present embodiment. FIG. In order to simplify the drawing, FIG. 2 shows only the magnetic films 1 to 3 of the magneto-optical recording medium 10 according to the embodiment shown in FIG. 1, and the arrows in the drawing show the directions of magnetization. .

First, a method of recording information on the magneto-optical recording medium 10 according to the present embodiment will be described with reference to FIGS. Before recording information on the magneto-optical recording medium 10, a large magnetic field is applied from the outside in a certain direction, etc.
As shown in FIG. 2A, the magnetization directions of the magnetic films 1 to 3 are aligned in a fixed direction (upward in this embodiment). However, in the overwrite type magneto-optical recording system, it is not always necessary to align the magnetization in one direction in advance).

Next, a light spot 7 is applied to the position where the recording of the magnetic film 3 is performed. Assuming that the temperature at the time when the heated portions of the magnetic films 1 to 3 are increased by the irradiation of the light spot is T, the relationship between the Curie temperatures of the magnetic films 1, 2, and 3 is Tc2 <Tc.
Since c1 <Tc3, when the light spot 7 is irradiated under the temperature condition of T> Tc3 and a recording magnetic field is applied downward from the outside,
Since T exceeds any of the Curie temperatures of the magnetic films 1 to 3, the magnetization directions of the irradiated magnetic films 1 to 3 are as shown in FIG.
As shown in (b), they are all inverted and face downward.

Next, as shown in FIG. 2C, for example, the light spot 7 is irradiated under the temperature condition of Tc3>T> Tc2 and an upward magnetic field is applied from outside to magnetize the magnetic film 1 and the magnetic film 2. (In this case, the magnetization of the magnetic films 1 and 2 is aligned in one direction in advance for the sake of simplicity, but in the overwrite type magneto-optical recording system, the magnetization is not necessarily adjusted in advance. It is not necessary to align in one direction).

Finally, a light spot 7 is irradiated to a position of the magnetic film 1 where recording is desired under the temperature condition of Tc1 <T <Tc3, and a recording magnetic field is applied downward from the outside. Then, as shown in FIG. 2D, the directions of the magnetizations of the magnetic film 1 and the magnetic film 2 in the irradiated portion are reversed and become downward. In this case, the information recorded on the magnetic film 3 is kept as it is because T does not reach the Curie temperature Tc3 of the magnetic film.

Thus, the magnetic film 1 and the magnetic film 2,
Different information can be recorded on the magnetic film 3. This is multilayer recording in the depth direction, and is equivalent to three-dimensional recording.

Next, a method for reproducing information recorded on the magneto-optical recording medium according to the present embodiment will be described with reference to FIGS.

First, as shown in FIG. 2E, T <Tc2
When the light spot 7 is radiated to the magneto-optical recording medium 10 under the above temperature condition, the Kerr rotation angle of the magnetic film 1 is so small that it does not contribute to the reproduction, and the reflected light from the magnetic film 1 does not contribute to the recording / reproduction. The information recorded on the magnetic film 1 can be reproduced by the magnetic Kerr effect due to the reflected light from the magnetic film 2 on which information is recorded in the same magnetization state as the film 1.

On the other hand, when the light spot 7 is irradiated on the magneto-optical recording medium 10 under the temperature condition of Tc2 <T <Tc1, T exceeds the Curie temperature of the magnetic film 2, so that the magnetic film 2 becomes paramagnetic. Since the reflected light from the film 1 has a small Kerr rotation angle and does not contribute to reproduction, the recorded information on the magnetic film 3 can be reproduced by the magnetic Kerr effect due to the reflected light from the magnetic film 3. As shown by the hatched portion in FIG. 2F, when the recorded information from the magnetic film 3 is reproduced,
However, since the information recorded on the magnetic film 1 is preserved, the temperature of the magneto-optical recording medium 10 is reduced to Tc2.
As shown in FIG. 2G, the magnetization state of the magnetic film 1 is transferred to the magnetic film 2 as shown in FIG. 2G, and the recorded information on the magnetic film 1 can be reproduced from the magnetic film 2 as before. Therefore, multi-layer recording / reproduction is possible, and the recording capacity can be doubled as compared with the current capacity.

Next, the structure and material of the magneto-optical recording medium 10 according to the present invention will be described in more detail with reference to FIG.

In the structure shown in FIG. 1, two dielectric films (interference film 4 and protection film 5) and three magnetic films 1 to
Although the film 3 is formed, a reflective film or the like may be further formed on the dielectric film (protective film 5) on the magnetic films 1 to 3. The magnetic film does not need to have three layers, and a multilayer film may be used for the purpose of improving the transfer characteristics of magnetization. Magnetic film 2
In order to make it difficult to transfer the magnetization between the magnetic film 3 and the magnetic film 3, a control magnetic film, a non-magnetic film, or the like may be interposed between the two layers. It is also possible to form the magnetic film 3 after forming the magnetic film 2 and then performing a surface treatment with oxygen-containing plasma or the like. Although the interference film 4 exists between the magnetic films 1 to 3 and the substrate 6 in FIG. 1, the magnetic films 1 to 3 may be formed directly on the substrate 6.

As the magnetic films 1 to 3, an amorphous alloy of a rare earth metal and an iron group transition metal, a periodic multilayer film of an iron group transition metal and a noble metal, a MnBi alloy, an oxide magnetic material, or the like may be used. Can be. A film containing TbFeCo as a main component is particularly desirable. Also, Ti, Cr, N
It is desirable to add one or more corrosion resistance improving elements such as i, Ta, and Pt. As the magnetic film 1, a film having a small Kerr rotation angle is used, but even if the Kerr rotation angle of the magnetic film 1 itself is not small, adjustment with other films such as a reflection film is performed to substantially reduce the Kerr rotation angle. Or a thinner film may be used.

As a material of the substrate 6, a synthetic resin such as polycarbonate or acrylic, glass, or the like can be used, and those coated with a resin or the like may be used. As the shape of the substrate 6, a disk shape or a card shape is used.

Finally, the inventor made magneto-optical recording media described in the following Test Examples 1 to 3 based on the above embodiment, and performed a signal recording / reproducing test.

Test Example 1 The substrate 6 was 130 m in diameter.
m, a polycarbonate substrate having a track pitch of 1.6 μm, a silicon nitride film of 80 nm as the interference film 4, a TbFeCo film of 30 nm as the magnetic film 1 on the substrate 6,
The magnetic film 2 is a 50 nm thick TbFe film, the magnetic film 3 is a 50 nm thick TbFeCo film slightly different in composition from the magnetic film 1,
A silicon nitride film having a thickness of 80 nm was sequentially formed as the protective film 5. The Curie temperature of the TbFeCo film of the magnetic film 1 is 200
° C, the Curie temperature of the TbFe film of the magnetic film 2 is 150 ° C,
The Curie temperature of the TbFeCo film of the magnetic film 3 is 250 ° C., and these film characteristics are as shown in FIG. However, in this case, the coercive force of the magnetic film 3 is larger than that of the other magnetic films 1 and 2 in a temperature range from room temperature to the Curie temperature of the magnetic film 3. TbF of magnetic film 1
An eCo film having a Kerr rotation angle that is negligible compared to other films is used.

Test Example 2 Using the same substrate 6 as used in Test Example 1, a silicon nitride film of 80 nm as the interference film 4, a DyFe film of 40 nm as the magnetic film 1, and a TbFeCo film as the magnetic film 2 were formed thereon. Is 50 nm, and a 50 nm thick TbFeCo film having a composition slightly different from that of the magnetic film 2 is used as the magnetic film 3.
m, a silicon nitride film having a thickness of 80 nm was sequentially formed as the protective film 5. The Curie temperature of the DyFe film of the magnetic film 1 is 220 ° C., the Curie temperature of the TbFeCo film of the magnetic film 2 is 150 ° C., and the Curie temperature of the TbFeCo film of the magnetic film 3 is 250 ° C. These film characteristics are shown in FIG. It is like. However, in this case, in the temperature range from room temperature to the Curie temperature of the magnetic film 3, the coercive force of the magnetic film 3 is larger than the coercive force of the other magnetic films 1 and 2. As the DyFe film of the magnetic film 1, a film having a Kerr rotation angle that is negligibly small compared to other films is used.

Test Example 3 The same substrate 6 as used in Test Example 1 was used, on which a silicon nitride film as the interference film 4 was 80 nm, a DyFe film as the magnetic film 1 was 40 nm, and a TbFeCo film as the magnetic film 2 was formed. Of 50 nm, a GdFeCo film as the magnetic film 3 of 50 nm, and a silicon nitride film of 80 nm as the protective film 5 were sequentially formed. The Curie temperature of the DyFe film of the magnetic film 1 is 220 ° C.
Curie temperature of the TbFeCo film was 150 ° C., and the magnetic film 3
The Curie temperature of the GdFeCo film is 300 ° C., and the film characteristics are as shown in FIG. As the DyFe film of the magnetic film 1, a film having a Kerr rotation angle that is negligibly small compared to other films is used.

While applying a recording magnetic field of, for example, about 400 Oe to the magneto-optical recording media of Test Examples 1 to 3,
A signal is recorded on the magnetic film 3 by irradiating a semiconductor laser beam having a linear velocity of 9.42 m / s, a high recording power of 8 mW, and a recording frequency of 9 MHz, and thereafter, a linear velocity of 9.42 m / s, a low recording power of 5 mW, and recording. A signal was recorded on the magnetic film 1 by irradiating a semiconductor laser beam having a frequency of 7 MHz. After that, when recording was reproduced with a semiconductor laser beam having a low reproducing power of 1 mW,
7 MHz signals recorded on the magnetic films 1 and 2 were reproduced. Next, when the recording was reproduced with a semiconductor laser beam having a high reproducing power of 3.5 mW, the 9 MHz recorded on the magnetic film 3 was reproduced.
Could be reproduced. When reproduction was performed with a semiconductor laser beam having a low reproduction power after reproduction with a high reproduction power, a 7 MHz signal recorded in the magnetic films 1 and 2 could be reproduced, and the magnetization state of the magnetic film 1 was favorably recorded on the magnetic film 2. It turned out that transcription was possible.

[0046]

As described above, according to the present invention,
In a magneto-optical recording medium, three-dimensional recording, that is, multilayer recording can be realized. Therefore, the density of magneto-optical recording can be increased, and a large-capacity optical recording medium can be realized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a magneto-optical recording medium according to an embodiment.

FIGS. 2A to 2D are diagrams for explaining a method of recording information on a magneto-optical recording medium according to the present embodiment, and FIGS.
(G) is a diagram for explaining a method of reproducing information recorded on the magneto-optical recording medium according to the present embodiment.

3A is a graph showing the relationship between the coercive force of the magnetic film 1 and the magnetic film 2 and the temperature, and FIG. 3B is a graph showing the relationship between the applied magnetic field of the magnetic film 1 and the magnetic film 2 and the Kerr effect; (C) is a graph showing the relationship between the coercive force of the magnetic film 2 and the magnetic film 3 and the temperature, and (d) and (e) are the applications of the magnetic film 2 and the magnetic film 3. Kerr loop showing the relationship between the magnetic field and the Kerr effect

[Explanation of symbols]

 1, 2, 3 magnetic film 4 interference film 5 protective film 6 substrate 7 light spot 10 magneto-optical recording medium

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G11B 11/10 506 G11B 11/10 586

Claims (4)

(57) [Claims] A magnetic film having at least a first, a second and a third magnetic perpendicular anisotropy in order from a light irradiation side;
The Curie temperatures Tc1, Tc2, and Tc3 of the first, second, and third magnetic films respectively satisfy a relationship of Tc2 <Tc1 <Tc3, and the Kerr rotation angle of the first magnetic film contributes to recording and reproduction. When the magnetization state of the first magnetic film is lower than Tc2, the magnetization state is always transferred to the second magnetic film, and the magnetization state of the second magnetic film and the third magnetic film is mutually reduced. A magneto-optical recording medium characterized by satisfying a non-transferred relationship. 2. A magnetic film having at least a first, a second and a third magnetic perpendicular anisotropy in order from a light irradiation side,
The Curie temperatures Tc1, Tc2, and Tc3 of the first, second, and third magnetic films respectively satisfy a relationship of Tc2 <Tc1 <Tc3, and the Kerr rotation angle of the first magnetic film contributes to recording and reproduction. The interface domain wall energy density σ1 acting between the first magnetic film and the second magnetic film, and the interface domain wall energy density acting between the second magnetic film and the third magnetic film. σ2, magnetizations Ms1, Ms2, and Ms3 of the first, second, and third magnetic films; coercive forces Hc1, Hc2, and Hc3 of the first, second, and third magnetic films; Between the thicknesses h1, h2 and h3 of the third magnetic film, Hc2 <Hc1 and σ1 / (2 × Ms2 × h2)> Hc2, and when Hc3 <Hc2, σ2 / (2 × Ms3 × h3) <Hc
3. When Hc3> Hc2, σ2 / (2 × Ms2 × h2) <Hc2
A magneto-optical recording medium characterized by satisfying the following relationship: 3. The method according to claim 1, wherein the temperature of the magneto-optical recording medium is increased to a temperature higher than the Curie temperature of the third magnetic film by using the magneto-optical recording medium according to claim 1. Recording on the film, and thereafter increasing the temperature of the magneto-optical recording medium to a temperature range from the Curie temperature of the first magnetic film to the Curie temperature of the third magnetic film, A recording method for a magneto-optical recording medium, wherein recording is performed on a film. 4. The magneto-optical recording medium according to claim 1, wherein the magneto-optical recording medium has a temperature range from the Curie temperature of the second magnetic film to the Curie temperature of the first magnetic film. The signal recorded on the third magnetic film is reproduced by increasing the temperature of the recording medium, and the temperature of the magneto-optical recording medium is increased to a temperature lower than the Curie temperature of the second magnetic film. 2. A recording / reproducing method for a magneto-optical recording medium, comprising: reproducing a signal recorded on the magnetic film.