JP2002123986A - Magneto-optical recording medium and its reproduction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a transfer magnetic field generated form a recording layer near the center of a mark and to increase a stable region against an external magnetic field during reproduction by forming a transfer stabilizing layer near the recording layer. SOLUTION: The medium has a reproducing layer 103 which becomes a perpendicular magnetization film at least at reproducing temperature and a recording layer 105 having perpendicular magnetization anisotropy so that the information in the recording layer 105 is transferred to the reproducing layer 103 by magnetostatic coupling force. A transfer stabilizing layer 106 having exchange coupling force or magnetostatic coupling force with the recording layer 105 is formed in the opposite side of the recording layer 105 to the reproducing layer 103 side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a magneto-optical recording medium used for recording or reproducing information utilizing a magneto-optical effect, and a reproducing method therefor.

[0002]

2. Description of the Related Art At present, various types of information recording systems have appeared, but magneto-optical recording has been attracting attention as a rewritable high-density recording system. Magneto-optical recording is a technique for recording and reproducing information on a magneto-optical recording medium using a light beam and a magnetic head.

One of the recording methods of magneto-optical recording is a magnetic field modulation recording method. The magnetic field modulation recording method irradiates a magneto-optical recording medium with a light beam having a constant intensity by a semiconductor laser or the like, raises a part of a recording layer formed on the magneto-optical recording medium to near the Curie temperature, and raises the Curie temperature. This is a recording method in which a recording magnetic domain is formed on a recording layer raised to the vicinity by a magnetic head that generates magnetic fields in different directions according to an information signal.

[0004] Another recording method is an optical modulation method. In the optical modulation method, a recording magnetic domain is formed in a recording layer formed on a magneto-optical recording medium by generating a magnetic field of a constant intensity from a magnetic head and modulating the intensity of a light beam according to an information signal. Recording method.

The magneto-optical recording reproduction method uses the magnetic Kerr effect. The magnetic Kerr effect is a phenomenon in which, when light is irradiated on a magnetized material surface, the plane of polarization of the reflected light rotates. In magneto-optical recording, reproduction is performed by irradiating a magneto-optical recording medium with linearly polarized laser light and changing the polarization plane of reflected light depending on the direction of magnetization. A rare earth-transition metal alloy is mainly used for the magnetic layer.

[0006] The linear recording density of a conventional magneto-optical recording medium greatly depends on the wavelength λ of a light beam during reproduction and the numerical aperture NA of an objective lens. That is, when the wavelength of the light beam at the time of reproduction and the numerical aperture of the objective lens are determined, the beam spot diameter is determined, and the shortest reproducible mark length is about 0.6λ / NA. On the other hand, the track density is mainly limited by crosstalk between adjacent tracks, and depends on the beam spot diameter of a light beam at the time of reproduction as well as the shortest mark length.
Therefore, in order to realize a higher density in a conventional magneto-optical recording medium, it is necessary to shorten the wavelength λ of the light beam at the time of reproduction or to increase the numerical aperture NA of the objective lens. But,
It is not easy to shorten the wavelength of the light beam due to problems such as the efficiency of the element and heat generation, and if the numerical aperture of the objective lens is increased, not only the processing of the lens becomes difficult, but also the distance between the lens and the disk becomes shorter. Mechanical problems such as colliding with the disk.

On the other hand, there is a magnetic super-resolution method as a recording / reproducing method capable of further increasing the density using a conventional reproducing optical system. The magnetic super-resolution method is a method in which reproduction is performed by masking adjacent marks by a thin film configuration of a magneto-optical recording medium. Also, in the magnetic super-resolution method, information is not reproduced by directly irradiating the recording layer with a light beam, but is reproduced by irradiating the reproduction layer onto which the information recorded on the recording layer is transferred with laser light. It is.

Here, CA which is one of the magnetic super-resolution methods is used.
A magneto-optical recording medium using the D (Center Aperture Detection) method will be described. The features of the CAD method are that the basic configuration is simple, and low power consumption is possible because a reproducing magnetic field is not required during reproduction.

FIG. 16 is a sectional view showing the structure of a magneto-optical recording medium using the CAD system. FIG. 16 shows a general configuration in which an enhancement layer 12 is first formed on a substrate 11, a reproduction layer 13, an intermediate layer 14, and a recording layer 15 are laminated thereon, and further, a protective layer 16, an overcoat layer 17 is formed. The basic configuration of the CAD system is a configuration of the recording layer 15 and the reproducing layer 13, and the intermediate layer 14 which is a non-magnetic layer formed between the recording layer 15 and the reproducing layer 13.

The reproducing layer 13 used in the CAD system is an in-plane magnetic film at room temperature, but has a characteristic such that a transition from an in-plane magnetic film to a perpendicular magnetic film occurs as the temperature rises. GdFeCo or the like is generally used for the reproducing layer 13. As the recording layer 15, a film having a large perpendicular magnetic anisotropy is used, for example, TbFeCo or DyFeCo.

A description will be given of a reproducing method of the CAD system.
When a light beam is irradiated from the substrate 11 side to the magneto-optical recording medium having such a configuration, a temperature gradient occurs in the beam spot, and a high-temperature region and a low-temperature region exist. In a low temperature region in the beam spot, the reproducing layer 13 becomes an in-plane magnetized film and does not contribute to the polar Kerr effect, and the recorded information held in the recording layer 15 is masked and cannot be seen.

On the other hand, in a high temperature area in the beam spot, the reproducing layer 13 becomes a perpendicular magnetization film, and the information recorded on the recording layer 15 is transferred to the reproducing layer 13 by magnetostatic coupling with the recording layer 15. Is done. Since the low-temperature area in the beam spot is masked by the reproducing layer 13, the recording layer 1 is formed only in the area smaller than the size of the beam spot.
Since the recording information of No. 5 is transferred, it is possible to reproduce a mark smaller than the beam spot.

[0013]

In the above-mentioned magneto-optical recording medium, it is required to reproduce small marks and simultaneously reproduce information stably. In the above-described configuration of the magneto-optical recording medium, since the transfer magnetic field generated from the recording layer is large near the mark edge, the information recorded on the recording layer can be sufficiently transferred. However, since the transfer magnetic field generated from the recording layer is small near the center of the mark, if an external magnetic field is generated near the magneto-optical recording medium during reproduction, the transfer magnetic field from the recording layer can sufficiently transfer information to the reproduction layer. No longer possible, which results in signal degradation.

In view of the above problems, the present invention increases the transfer magnetic field generated from the recording layer near the center of the mark by forming a transfer stable layer near the recording layer, thereby increasing the stable area against an external magnetic field during reproduction. It is an object of the present invention to provide a magneto-optical recording medium and a reproducing method therefor.

[0015]

In order to solve the above-mentioned problems, a magneto-optical recording medium according to the present invention has a reproducing layer which becomes a perpendicular magnetic film at least at a reproducing temperature, and a recording layer having a perpendicular magnetic anisotropy. A magneto-optical recording medium in which information of the recording layer is transferred to the reproducing layer by magnetostatic coupling force, wherein the recording layer has an exchange coupling force with the recording layer on a side opposite to the reproducing layer side. The transfer stabilizing layer is provided.

Alternatively, at least a reproducing layer which becomes a perpendicular magnetic film at a high temperature and a recording layer having perpendicular magnetic anisotropy, and light which is transferred to the reproducing layer by the magnetostatic coupling force of the information of the recording layer. A magnetic recording medium, wherein a transfer stable layer having a magnetostatic coupling force with the recording layer is provided on a side of the recording layer opposite to the reproduction layer, with a non-magnetic layer interposed therebetween. This is a magneto-optical recording medium.

Further, the magneto-optical recording medium is characterized in that a transfer stable layer is provided on the opposite side of the recording layer from the reproduction layer side via the magnetization control layer.

Further, the magneto-optical recording medium is characterized in that a transfer stabilizing layer is provided on a side opposite to the reproducing layer side of the recording layer via a thin interface layer.

The perpendicular magnetic anisotropy constant of the transfer stable layer is 2 × 1
0 ⁵ (erg / cm ³ ) or less.

A magneto-optical recording medium characterized in that the transfer stabilizing layer contains at least a transition metal element.

The magneto-optical recording medium is characterized in that the transfer stable layer is a rare earth-transition metal film.

A magneto-optical recording medium characterized in that the transfer stabilizing layer contains at least Gd.

The ratio of Gd in the transfer stable layer is 19 to 23 (a
t. %).

The magneto-optical recording medium is characterized in that the transfer stable layer is at least a perpendicular magnetization film in a temperature range from room temperature to Curie temperature.

A magneto-optical recording medium characterized in that an intermediate layer which is a non-magnetic film is provided between a reproducing layer and a recording layer.

The magneto-optical recording medium is characterized in that the intermediate layer is a dielectric film.

A magneto-optical recording medium characterized in that a reflecting layer capable of reflecting incident light is provided between a reproducing layer and a recording layer.

At least Al, Cu, Au, A
(g) a magneto-optical recording medium containing one or more metals.

A magneto-optical recording medium characterized in that a reproduction auxiliary layer, which is an in-plane magnetization film, is provided between the reproduction layer and the recording layer.

A recording medium characterized in that a reproduction enlargement layer for enlarging a signal is provided on the light incident side of the reproduction layer.

At least Al, Cu, Au,
A magneto-optical recording medium comprising one or more metals from Ag.

The magneto-optical recording medium is characterized in that the non-magnetic layer is a dielectric film.

The magneto-optical recording medium is characterized in that the thickness of the interface layer is 2 nm or less.

Further, the reproducing method of the magneto-optical recording medium of the present invention comprises a reproducing layer which becomes a perpendicular magnetic film at least at a reproducing temperature;
A recording layer having perpendicular magnetic anisotropy, and irradiating a light beam to a magneto-optical recording medium on which information on the recording layer is transferred to a reproducing layer by magnetostatic coupling, to thereby record information recorded on the recording layer. In a method for reproducing a magneto-optical recording medium for performing reproduction by magnetically coupling the reproduction layer and the recording layer, the transfer stabilization layer provided on the recording layer opposite to the reproduction layer side, It is characterized in that the recording layer is reproduced with a magnetic coupling force.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to specific embodiments, but the present invention is not limited to the following embodiments unless it exceeds the gist.

(Embodiment 1) First, Embodiment 1 of the present invention will be described with reference to the drawings. FIG.
FIG. 1 is a cross-sectional view illustrating a configuration of a magneto-optical recording medium according to Embodiment 1 of the present invention. In FIG. 1, a substrate 101 is a polycarbonate substrate provided with a guide groove for tracking a light beam. The polycarbonate substrate is
Generally, it is often used as a substrate of a magneto-optical recording medium because of its easy molding. The substrate 101 has a land / groove configuration, and the track width is 0.6 μm.

The magneto-optical recording medium according to the present embodiment is
First, an enhancement layer 102 made of a SiN film is formed, and a reproduction layer 10 made of a GdFeCo film is formed thereon.
3. An intermediate layer 104 made of a SiN film, a recording layer 105 made of a TbFeCo film are stacked, a transfer stable layer 106 made of a GdFeCo film is further stacked, a heat control layer 107 made of an AlTi film, and an overcoat made of an ultraviolet curable resin. This is a configuration in which a layer 108 is formed. The transfer stabilizing layer 10
A similar effect can be obtained by a structure in which a nonmagnetic layer such as a SiN film is formed after the formation of No. 6 and the heat control layer 107 is further formed.

A method for forming a magneto-optical recording medium according to the present embodiment will be described. A sputtering apparatus was used to form each thin film on the substrate 101. TbFeCo alloy target, GdF
eCo alloy target, Si target and AlTi
Each target is placed on an independent cathode. The substrate 101 made of polycarbonate is set on a substrate holder in a sputtering apparatus. After placing the substrate 101 in the sputtering apparatus, the inside of the chamber of the sputtering apparatus was evacuated with a cryopump until a high vacuum of 2 × 10 ⁻⁷ Torr or less was reached.

After evacuation to a high vacuum, Ar gas was introduced into the chamber at 2 × 10 ^-3 Torr and N ₂ gas was introduced at 4 × 10 ^-3 Ton.
rr was introduced, an input power of 1 kW was applied, and a SiN film as the enhancement layer 102 was formed on the substrate 101 by DC sputtering. In the present embodiment, the thickness of the SiN film as the enhancement layer 102 is set to 80 nm.

Next, the degree of vacuum in the chamber is again set to 2 ×
At 10 ^-7 Torr or less, Ar gas is introduced into the chamber at 5 × 10 ^-3 Torr. After the introduction of the Ar gas, a GdFeCo film serving as the reproducing layer 103 was formed on the enhance layer 102. The sputtering method is a DC sputtering method as in the case of the enhance layer 102. In this embodiment, the thickness of the GdFeCo film as the reproducing layer 103 is set to 3
It was set to 0 nm.

In this embodiment, the reproducing layer 10
3, the composition of the GdFeCo film was changed to Gd _30.6 Fe _61.1 Co
_{8.3 (at.%)} . Reproduction layer 103 in the present embodiment
GdFeCo film has a Curie temperature of 320 ° C., 1
GdFeC having a rare-earth-rich composition such that a transition from an in-plane magnetization film to a perpendicular magnetization film occurs in a temperature region around 50 ° C.
o film.

After forming the reproducing layer 103, 2 × 10 ^{−7 is} again formed.
Evacuate to Torr, and place the intermediate layer 1 on the reproduction layer 103.
04 was formed. The intermediate layer 104 is a SiN film similarly to the enhance layer 102, and the film forming conditions are the same as those of the enhance layer 102.
And Ar gas in the chamber is 2 × 10 ⁻³ T
Orr and N ₂ gas were introduced at 4 × 10 ⁻³ Torr,
It was formed by applying a power of 1 kW.

The thickness of the intermediate layer 104 is the same as that of the reproducing layer 103.
It strongly affects the magnetostatic coupling force with the recording layer 105 formed on the intermediate layer 104. The thinner the intermediate layer 104, the shorter the distance between the reproducing layer 103 and the recording layer 105,
Since the magnetostatic coupling force is increased, the thickness of the intermediate layer 104 is set to 80
nm or less, more preferably 30 nm or less. However, when the thickness of the intermediate layer 104 is extremely small, the exchange coupling force between the reproducing layer 103 and the recording layer 105 becomes larger than the magnetostatic coupling force.
Must be 1 nm or more. In the present embodiment, the thickness of the intermediate layer 104 is 10 nm.

Next, after evacuating again to 2 × 10 ⁻⁷ Torr, Ar gas was introduced into the chamber at 5 × 10 ⁻³ Torr.
rr was introduced, and a TbFeCo film as the recording layer 105 was formed on the intermediate layer 104 with a thickness of 50 nm.

[0045] In this embodiment, the composition of the TbFeCo film is a recording layer 105, Tb _{22 .1} Fe _71.3 Co
_{6.6 (at.%)} . Further, the recording layer 105 of the present embodiment
The TbFeCo film having a Curie temperature of 240 ° C. is rich in transition metal.

After evacuating again to 2 × 10 ⁻⁷ Torr, Ar gas was introduced into the chamber at 5 × 10 ⁻³ Torr, and a GdFeCo film serving as the transfer stabilizing layer 106 was deposited on the recording layer 105 to a thickness of 30 nm. It was formed thick.

The inside of the chamber was evacuated again to 2 × 10 ⁻⁷ Torr or less. After evacuation, Ar gas is introduced into the chamber at 1.5 × 10 ⁻³ Torr. After the introduction of the Ar gas, an input power of 600 W was applied, and an AlTi film serving as the thermal control layer 107 was formed by DC sputtering.

The magneto-optical recording medium in which each thin film was formed on the substrate 101 under the above conditions was taken out of the chamber of the sputtering apparatus, and an ultraviolet curable resin was applied to the film surface side of the magneto-optical recording medium by spin coating. The overcoat layer 108 was formed by irradiating ultraviolet rays.
In the present embodiment, the thickness of the overcoat layer 108 is set to 10 μm by controlling the viscosity of the ultraviolet curable resin and the rotation speed of the spin coater.

The perpendicular magnetic anisotropy constant of the transfer stabilizing layer 106 of this embodiment is 2 × 10 ⁵ erg / cm ³ .

In the present embodiment, the thermal control layer 107 having a higher thermal conductivity than other films such as the reproducing layer 103 and the recording layer 105 is formed. Thermal control layer 107 having high thermal conductivity
Is formed, when a light beam is irradiated, it is possible to suppress the spread of heat in the lateral direction in the film and to release the heat in the thickness direction in the film. Therefore, when the light beam is irradiated, the temperature distribution in the light beam becomes steep, so that the reproducing layer 10
3 steeply transitions from the in-plane magnetization film to the perpendicular magnetization film, and the magnetization also sharply increases in the recording layer 105, and the reproduction resolution increases.

As the thickness of the heat control layer 107 increases, the effect of dissipating heat in the light beam in the film thickness direction increases, and the reproduction resolution increases, but at the same time, the recording sensitivity is also greatly affected. If the thickness of the thermal control layer 107 is too large, a high recording power is required.

For the above reason, the thickness of the thermal control layer 107 is preferably set to 5 to 200 nm. In this embodiment, the thickness of the heat control layer 107 is set to 30 nm.

The reproducing layer 1 of the magneto-optical recording medium according to the present invention
03 used a rare earth-transition metal alloy having a composition in which the sublattice magnetic moment of the rare earth element is dominant at room temperature. The reproducing layer 103 has magnetic properties as shown in FIG. 2 depending on the temperature. FIG. 2A is a diagram showing the relationship between the Kerr rotation angle and the external magnetic field at room temperature. Since the reproducing layer 103 is an in-plane magnetized film at room temperature, the magnetization is hardly oriented in the vertical direction with a small external magnetic field in the vertical direction, and a very large external magnetic field is required to direct the magnetization in the vertical direction.

FIG. 2B is a diagram showing the relationship between the Kerr rotation angle and the external magnetic field at a temperature at which the magnetization transitions from the in-plane direction to the vertical direction. In this temperature range, the magnetization tends to be oriented in the in-plane direction and the magnetization in the vertical direction. Therefore, when a large external magnetic field is applied, all the magnetizations in the film are oriented in the vertical direction. Then, the film becomes an in-plane magnetized film, and the Kerr rotation angle is small.

FIG. 2C is a diagram showing the relationship between the Kerr rotation angle and the external magnetic field at a high temperature. At high temperatures, the film becomes a perpendicular magnetization film, saturates even with a small external magnetic field, and provides a large Kerr rotation angle. As shown in FIG. 2, the reproducing layer 103 is a film that becomes an in-plane magnetic film at room temperature and becomes a perpendicular magnetic film at higher temperatures.

In the reproducing layer 103, the temperature region where the transition from the in-plane magnetization film to the perpendicular magnetization film can be set by changing the ratio of each element of the reproduction layer 103. Generally, in the case of a rare earth-transition metal alloy, when the ratio of the rare earth element is increased, the temperature region where the transition from the in-plane magnetization film to the perpendicular magnetization film is increased. Conversely, when the temperature region where the in-plane magnetization film transitions to the perpendicular magnetization film is reduced, the ratio of the rare earth element may be reduced.

FIG. 3 shows that the reproducing layer 103 becomes an in-plane magnetic film at room temperature and a perpendicular magnetic film at high temperature as described above.
FIG. 3 is a diagram showing a relationship between perpendicular magnetic anisotropy energy Ku and demagnetizing field energy 2πMs ² of FIG. Assuming that the perpendicular magnetic anisotropy energy is Ku and the saturation magnetization is Ms, the following equation holds when the reproducing layer 103 is at room temperature.

Ku <2πMs ² where 2πMs ² is demagnetizing field energy. Ku is 2
If it is smaller than πMs ² , the magnetic layer becomes an in-plane magnetized film.
Assuming that the temperature at which Ku and 2πMs ² coincide with each other is Tm, the reproducing layer 102 becomes an in-plane magnetized film in a low temperature region lower than Tm. As shown in FIG. 3, when the temperature of the magnetic layer increases, the magnitude of Ku and 2πMs ² approaches, and when the temperature exceeds Tm, the following equation is obtained.

Ku> 2πMs ^{2 The} reproducing layer 103 becomes a perpendicular magnetization film when this equation is satisfied.

Since the reproducing layer 103 plays a role of reproducing the information recorded on the recording layer 105, it is preferable that the Kerr rotation angle is large. FIG. 4 is a diagram showing the relationship between the Kerr rotation angle and the Curie temperature in the reproducing layer 103. As shown in FIG. 4, as the Curie temperature increases, the Kerr rotation angle increases. As described above, the material and composition of the reproducing layer 103 are suitable for increasing the Curie temperature. In this embodiment, the Curie temperature of the GdFeCo film serving as the reproducing layer 103 is 320 ° C.

FIG. 5 shows the recording layer 1 formed in this embodiment.
FIG. 5 is a diagram showing a relationship between a saturation magnetization Ms and a temperature of No. 05. The magnetostatic coupling force has a strong correlation with the magnetic moment, and the larger the magnetic moment, the greater the magnetostatic coupling force. Since the magnetic moment is the product of the saturation magnetization and the film thickness, the saturation magnetization has a great effect on the magnetostatic coupling force. The recording layer 105 formed in this embodiment is a transition metal-rich TbFeCo film having a Curie temperature of 240 ° C. In the recording layer 105, when the compensation temperature is near room temperature, the difference between the saturation magnetization at room temperature and the saturation magnetization at the transfer temperature becomes larger, and the change in saturation magnetization with temperature becomes sharper.

Further, since the perpendicular magnetic anisotropy is large and the coercive force is large at room temperature, it is possible to stably hold recorded information. Recording layer 105 formed in this embodiment
Is substantially zero at room temperature, and as the temperature increases, the saturation magnetization of the recording layer 105 increases. At a predetermined temperature, that is, the temperature at which the recording information is transferred to the reproducing layer 103, the recording layer 105 It indicates a value of saturation magnetization at which a signal can be sufficiently transferred from the information recorded in 105 to the reproduction layer 103.

The film thickness of the recording layer 105 is desirably 25 nm or more because it is necessary to increase the magnetic moment of the recording layer 105 in order to transfer a signal to the reproducing layer 102. However, if the thickness of the recording layer 105 is too large, the power of the light beam required for increasing the temperature increases, which causes a reduction in recording sensitivity.
It is desirable that the film thickness of No. 5 is 200 nm or less. In the present embodiment, the thickness of the recording layer 105 is set to 50 nm.

Next, the recording / reproducing characteristics of the magneto-optical recording medium according to the present embodiment will be described. In the reproducing method of the present invention, a semiconductor laser having a wavelength of 650 nm and an objective lens having an NA of 0.6 were used. The linear velocity of the medium was 3.5 m / s.

For recording signals on the magneto-optical recording medium, an optical pulse magnetic field modulation system was used. Recording power of 10 mW, du
At a ty of 50%, a light beam is applied to the magneto-optical recording medium to raise the temperature of the recording layer 105 to near the Curie temperature. At the same time, signal recording was performed by keeping the magnetic head close to the surface opposite to the light beam and modulating the direction of the magnetic flux generated by the magnetic head with a recording magnetic field of 350 Oe.

To reproduce the information recorded in the recording layer 105, a light beam is applied to the magneto-optical recording medium, and the temperature of the reproducing layer 103 in the beam spot is increased to form a region of a perpendicular magnetization film. At the same time, the temperature of the recording layer 105 also increases, and the magnetic moment of the recording layer 105 in the beam spot increases. Due to the magnetostatic coupling between the reproducing layer 103 and the recording layer 105,
The signal of the recording layer 105 is transferred to the reproduction layer 103. The signal of the light beam reflected by the reproducing layer 103 was detected by a magneto-optical effect.

Table 1 shows the external magnetic field characteristics during reproduction of the magneto-optical recording medium formed in the present embodiment. The mark length was measured at 1.88 μm and 0.47 μm.

[0068]

[Table 1]

For comparison, an external magnetic field characteristic during reproduction of a magneto-optical recording medium in which the transfer stabilizing layer 106 is not formed is also shown as Conventional Example 1. The magneto-optical recording medium in which the transfer stabilizing layer 106 is not formed has a configuration in which the transfer stabilizing layer 106 is removed from the configuration of the magneto-optical recording medium of the present embodiment.

The stable area against an external magnetic field during reproduction is obtained by applying an external magnetic field and obtaining a CN obtained when there is no external magnetic field.
The region of the magnetic field within 1 dB down from the ratio is shown. The CN ratio is a ratio between carrier and noise, and can be expressed by the following equation.

CN ratio (dB) = 20 log ₁₀ (carrier / noise) As shown in Table 1, the magneto-optical recording medium on which the transfer stabilizing layer 106 was formed was different from the conventional example 1 regardless of the mark length. The stable area against an external magnetic field during reproduction is large. When the mark length is 1.88 μm, the stable area of Conventional Example 1 is 50 Oersted, whereas the transfer stable layer 1 is
The stable area of the magneto-optical recording medium formed in the present embodiment in which No. 06 is formed is as large as 77 Oe.

Even in the case of a mark having a short mark length of 0.47 μm, the magneto-optical recording medium formed in the present embodiment in which the transfer stable layer 106 is formed, whereas the stable area of the conventional example 1 is 170 Oersted. Is as large as 272 Oe. A description will be given of the fact that the stable area with respect to an external magnetic field during reproduction of the magneto-optical recording medium of the present embodiment in which the transfer stable layer 106 is formed is increased.

FIG. 6A shows a transfer magnetic field generation mechanism when the transfer stabilization layer 106 is an Fe film in the magneto-optical recording medium of the present embodiment. For comparison, FIG. 17A shows a transfer magnetic field generation mechanism in a conventional magneto-optical recording medium in which the transfer stabilizing layer 106 is not formed.

FIG. 6A shows a case where the light beam is irradiated near the center of the figure. In the region irradiated with the light beam, the temperature of the recording layer 105 increases, so that the magnetization of the recording layer 105 increases as described with reference to FIG.
In this case, since the recording layer 105 is rich in transition metal, the magnetic moment 201 of the transition metal element is much larger than the magnetic moment 202 of the rare earth element as shown in FIG. In a region not irradiated with the light beam, the magnetization of the recording layer 105 is small, and the magnetic moment 201 of the transition metal element is slightly larger than the magnetic moment 202 of the rare earth element.

In this embodiment, since the transfer stabilizing layer 106 is formed adjacent to the recording layer 105, exchange coupling works between the transfer stabilizing layer 106 and the recording layer 105. When the exchange coupling is working, the transfer stabilizing layer 106 and the recording layer 1
05 magnetic moment 201 of each transition metal element
Are oriented such that no interface domain wall occurs. The magnetic moment 201 of the transition metal element shows a direction as shown in FIG. Also, the magnetic moment 2 of the rare earth element
Since 02 is opposite to the direction of the magnetic moment 201 of the transition metal element, the direction is as shown by the dotted line in FIG.

FIG. 17A shows a mechanism for generating a transfer magnetic field generated from the recording layer 15 of a conventional magneto-optical recording medium. FIG. 17B shows the magnitude of the transfer magnetic field generated from the recording layer 15 at each location.

In the conventional magneto-optical recording medium as well, in the vicinity of the edge of the mark, since the magnetizations in the opposite directions are arranged adjacent to each other, the transfer magnetic field generated from the recording layer 15 becomes large. However, in the vicinity of the center of the mark, magnetizations in the same direction are arranged, so that the transfer magnetic field generated from the recording layer 15 is very small. For this reason, if an external magnetic field is generated near the magneto-optical recording medium during reproduction, the recording / reproducing characteristics deteriorate even with a small external magnetic field. Particularly in the case of a long mark, the above-described deterioration is severe near the center of the mark because the mark is away from the magnetization in the opposite direction of the mark edge.

On the other hand, in the magneto-optical recording medium of the present embodiment, the recording layer 105 at the center of the mark is magnetically coupled to the transfer stabilizing layer 106 which is an in-plane magnetization film, And magnetic coupling work. With such a mechanism, since the magnetic flux has a closed magnetic path structure, as shown in FIG. 6B, the transfer magnetic field becomes large even at the center of the mark. Since the transfer magnetic field at the center of the mark is increased, the stable area against the external magnetic field during reproduction is increased.

(Embodiment 2) Next, Embodiment 2 of the present invention will be described with reference to the drawings. FIG.
FIG. 9 is a cross-sectional view illustrating a configuration of a magneto-optical recording medium according to Embodiment 2 of the present invention. In FIG. 7, a substrate 101 is a polycarbonate substrate provided with a sample servo for tracking a light beam. The track width of the substrate 101 is 0.6 μm.

The magneto-optical recording medium according to the present embodiment
First, an enhancement layer 102 made of a SiN film is formed, and a reproduction layer 10 made of a GdFeCo film is formed thereon.
3. Reproducing auxiliary layer 110 made of GdFeCr film, SiN
An intermediate layer 104 made of a film, a recording layer 105 made of a TbFeCo film, and a nonmagnetic layer 10 made of a SiN film.
9, a transfer stable layer 106 made of a GdFeCo film is formed, a heat control layer 107 made of an AlTi film, and an overcoat layer 108 made of an ultraviolet curable resin are formed.

After the formation of the transfer stabilizing layer 106, the Si
A similar effect can be obtained by a configuration in which a nonmagnetic layer such as an N film is formed, and the heat control layer 107 is further formed. The perpendicular magnetic anisotropy constant of the transfer stable layer 106 of the present embodiment is 1.8 × 1
0 ⁵ erg / cm ³ .

A method for forming the GdFeCr film serving as the reproduction auxiliary layer 110 will be described. Reduce the degree of vacuum in the chamber to 2
Ar gas is introduced into the chamber at 5 × 10 ⁻³ Torr at a pressure of × 10 ⁻⁷ Torr or less. After the introduction of the Ar gas, a GdFeCr film serving as the reproduction auxiliary layer 110 was formed. In the present embodiment, the GdFeC
The thickness of the r film was set to 20 nm.

In this embodiment, the composition of the GdFeCr film as the auxiliary reproduction layer 110 is changed to Gd _12.0 Fe _83.0
Cr _{5.0 (at.%)} . In the present embodiment, the GdFeCr film serving as the reproduction auxiliary layer 110 has a Curie temperature of 15
It is always an in-plane magnetized film from 0 ° C., room temperature to the Curie temperature.

A method for forming the SiN film as the non-magnetic layer 109 will be described. Nonmagnetic layer 109, after evacuated to a high vacuum, Ar gas 2 × 10 ^-3 Torr and N ₂ gas was introduced 4 × 10 ^-3 Torr to the chamber, the input power 1
kW was applied, and a SiN film was formed by the DC sputtering method in the same manner as the enhancement layer 102. In the present embodiment, the thickness of the SiN film as the nonmagnetic layer 109 is set to 5
２０20 nm.

The other films were formed on the substrate 101 by DC sputtering under the same film forming conditions as in the magneto-optical recording medium of the first embodiment.

In this embodiment, recording and reproduction of signals on and from the magneto-optical recording medium are performed in the same manner as in the first embodiment. Table 2 shows the external magnetic field characteristics during reproduction of the magneto-optical recording medium formed in the present embodiment. The mark length was measured at 1.88 μm and 0.47 μm. In this embodiment, the transfer stable layer 106 is a transition metal-rich GdF that is always an in-plane magnetized film from room temperature to the Curie temperature.
An eCo film, an in-plane magnetized film at room temperature, a GdFeCo film as an in-plane perpendicular film which becomes a perpendicular magnetized film near the reproduction temperature, and a rare earth-rich GdFeCo film as an in-plane magnetized film from room temperature to the Curie temperature were studied. .

[0087]

[Table 2]

For comparison, an external magnetic field characteristic during reproduction of a magneto-optical recording medium in which the transfer stabilizing layer 106 is not formed is also shown as Conventional Example 2. The magneto-optical recording medium in which the transfer stabilizing layer 106 is not formed has a configuration in which the transfer stabilizing layer 106 is removed from the configuration of the magneto-optical recording medium of the present embodiment. The stable area against the external magnetic field at the time of reproduction
The region of the magnetic field within 1 dB down from the CN ratio obtained when there is no external magnetic field is shown.

As shown in Table 2, the transfer stable layer 106
The magneto-optical recording medium on which is formed a large stable area against an external magnetic field during reproduction regardless of the mark length. When the mark length is 1.88 μm, the stable area of Conventional Example 2 is 59 Oersted, whereas the stable area of the magneto-optical recording medium formed with the transfer stable layer 106 according to the present embodiment is 1 Oe.
It is about doubled from 08 to 128 Oersted.

Even in the case of a mark having a short mark length of 0.47 μm, the magneto-optical recording medium formed in the present embodiment having the transfer stable layer 106 is different from the conventional example 2 in which the stable area is 76 Oersted. The stable region of 225-34
It is as large as 9 Oersted.

A description will be given of the fact that the stable area with respect to an external magnetic field during reproduction of the magneto-optical recording medium of the present embodiment having the transfer stabilizing layer 106 is increased. First, the case where the transfer stable layer 106 is formed from a transition metal-rich GdFeCo film that is an in-plane magnetized film from room temperature to Curie temperature will be described. FIG. 8A shows that in the magneto-optical recording medium of the present embodiment, the transfer stable layer 106 is a transition metal-rich GdFeC which is always an in-plane magnetized film from room temperature to the Curie temperature.
The generation mechanism of the transfer magnetic field when the o film is formed is shown.

FIG. 8A shows a case where a light beam is irradiated near the center of the figure. In a region where the light beam is irradiated, the temperature of the recording layer 105 is increased.
As described with reference to FIG. 5, the magnetization of the recording layer 105 increases. In this case, since the recording layer 105 is rich in transition metal, the magnetic moment 201 of the transition metal element is much larger than the magnetic moment 202 of the rare earth element as shown in FIG. In a region not irradiated with the light beam, the magnetization of the recording layer 105 is small, and the magnetic moment 201 of the transition metal element is slightly larger than the magnetic moment 202 of the rare earth element.

In this embodiment, since the transfer stable layer 106 and the recording layer 105 are formed with the nonmagnetic layer 109 interposed therebetween, the transfer stable layer 106 and the recording layer 105 are more magnetostatically coupled than exchange coupled. Works stronger. When the magnetostatic coupling is working, the magnetic moment is oriented so that the magnetic flux of the transfer stabilizing layer 106 and the magnetic flux of the recording layer 105 form a closed magnetic circuit structure. For this reason, the magnetic moment 201 of the transition metal element of the transfer stable layer 106 shows a direction as shown in FIG. This is opposite to the case where the transfer stable layer 106 and the recording layer 105 of the first embodiment are adjacent to each other. Since the magnetic moment 202 of the rare earth element is opposite to the direction of the magnetic moment 201 of the transition metal element, the magnetic moment 202 has a direction shown by a dotted line in FIG.

Next, the transfer stable layer 106 is a rare-earth-rich GdF which is always an in-plane magnetized film from room temperature to the Curie temperature.
The case where an eCo film is formed will be described. FIG. 8B
Next, the transfer stabilization layer 106 of the magneto-optical recording medium of the present embodiment is used.
Shows a transfer magnetic field generation mechanism when a rare-earth-rich GdFeCo film, which is an in-plane magnetized film, is always formed from room temperature to the Curie temperature.

In the case of the rare earth rich transfer stabilization layer 106 which is always an in-plane magnetization film from room temperature to the Curie temperature, the transfer stabilization layer 106 and the recording layer 105 are exchanged similarly to the case of the transition metal rich transfer stabilization layer 106. Since the magnetostatic coupling works more strongly than the coupling, the magnetic moment of the transition metal element 20
The direction of 1 and the direction of the magnetic moment 202 of the rare earth element are as shown in FIG.

In the magneto-optical recording medium of the present embodiment, the recording layer 105 at the center of the mark is magnetically coupled to the transfer stabilizing layer 106, which is an in-plane magnetization film, and this is magnetically coupled to the magnetization of the adjacent mark. The bond works. With such a mechanism, the magnetic flux has a closed magnetic path structure, so that the transfer magnetic field is large even at the center of the mark. Since the transfer magnetic field at the center of the mark is increased, the stable area against the external magnetic field during reproduction is increased.

Table 3 shows the reproduction time when the thickness of the non-magnetic layer 109 formed between the recording layer 105 and the transfer stabilization layer 106 of the magneto-optical recording medium according to the present embodiment is changed. 3 shows a stable region with respect to an external magnetic field. Even when the thickness of the nonmagnetic layer 109 is set to 5 nm, 10 nm, and 20 nm, the stable region against the external magnetic field during reproduction is larger than that of the conventional example 2, and the effect of the present invention is exhibited. From the results shown in Table 3, it can be said that even if the thickness of the nonmagnetic layer 109 is 5 nm to 20 nm, the recording layer 105 and the transfer stabilizing layer 106 operate as described above.

[0098]

[Table 3]

Table 4 shows that the thickness of the transfer stable layer 106 of the magneto-optical recording medium according to the present embodiment is 15 nm, 30 n
It shows a stable region with respect to an external magnetic field during reproduction when m and 45 nm. The thickness of the transfer stable layer 106 is 15 n
Even when the thickness is set to m to 45 nm, the effect of the present invention is sufficiently exhibited.

[0100]

[Table 4]

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to the drawings. FIG.
FIG. 9 is a cross-sectional view illustrating a configuration of a magneto-optical recording medium according to Embodiment 3 of the present invention. In FIG. 9, a substrate 101 is a polycarbonate substrate provided with a sample servo for tracking a light beam. The track width of the substrate 101 is 0.8 μm.

The magneto-optical recording medium according to the present embodiment is
First, an enhancement layer 102 made of a SiN film is formed, and a reproduction layer 10 made of a GdFeCo film is formed thereon.
3. Intermediate layer 104 made of SiN film, recording layer 105 made of TbFeCo film, magnetization control layer 1 made of TbFe film
11, a transfer stable layer 106 made of a GdFeCo film is formed, and a heat control layer 107 made of an AlTi film is formed.
This is a configuration in which an overcoat layer 108 made of an ultraviolet curable resin is formed. After forming the transfer stable layer 106,
Forming a non-magnetic layer such as a SiN film,
The same effect can be obtained even in the configuration in which 7 is formed.

In the present embodiment, the magnetization control layer 111 is used. However, by stacking the magnetization control layer 111 on the recording layer 105, the transfer magnetic field can be made steep with respect to the temperature. When the transfer magnetic field is sharpened, the reproduction resolution is increased, and a small mark can be reproduced with a high CN ratio.

A method for forming a TbFe film as the magnetization control layer 111 will be described. The degree of vacuum in the chamber is 2 × 1
0 ^-7 Torr or less, and Ar gas is
× 10 ^-3 Torr is introduced. After the introduction of the Ar gas, a TbFe film serving as the magnetization control layer 111 was formed.

In this embodiment, the TbFeCo film serving as the recording layer 105 has a thickness of 35 nm, and the magnetization control layer 11 has a thickness of 35 nm.
The thickness of the TbFe film, which was 1, was 35 nm.

In this embodiment, the composition of the TbFe film as the magnetization control layer 111 is changed to Tb _30.6 Fe
_{61.1 (at.%)} . Magnetization control layer 1 in the present embodiment
The TbFe film 11 is a rare-earth-rich film at room temperature and a Curie temperature of 150 ° C.

The other films were formed on the substrate 101 by the DC sputtering method under the same film forming conditions as those of the magneto-optical recording media of the first and second embodiments.

In this embodiment, recording and reproduction of signals on and from the magneto-optical recording medium are performed in the same manner as in the first embodiment. Table 5 shows external magnetic field characteristics during reproduction of the magneto-optical recording medium formed in the present embodiment. The mark length was measured at 1.88 μm and 0.47 μm. In this embodiment, the transfer stable layer 106 is a transition metal rich GdFe that is an in-plane magnetized film from room temperature to Curie temperature.
A Co film and a rare earth-rich GdFeCo film, which is an in-plane magnetized film from room temperature to Curie temperature, were studied.

[0109]

[Table 5]

For comparison, an external magnetic field characteristic during reproduction of a magneto-optical recording medium in which the transfer stabilizing layer 106 is not formed is also shown as Conventional Example 3. The magneto-optical recording medium in which the transfer stabilizing layer 106 is not formed has a configuration in which the transfer stabilizing layer 106 is removed from the configuration of the magneto-optical recording medium of the present embodiment. The stable area against the external magnetic field at the time of reproduction
The region of the magnetic field within 1 dB down from the CN ratio obtained when there is no external magnetic field is shown.

As shown in Table 5, the transfer stable layer 106
The magneto-optical recording medium on which is formed a large stable area against an external magnetic field during reproduction regardless of the mark length. When the mark length is 1.88 μm, the stable area of the conventional example is 40 Oersted, whereas the stable area of the magneto-optical recording medium formed with the transfer stable layer 106 according to the present embodiment is 98.
It is as large as -102 Oersteds.

Even in the case of a mark having a short mark length of 0.47 μm, the magneto-optical recording medium formed in the present embodiment having the transfer stable layer 106 is different from the conventional example 3 in which the stable area is 154 Oersted. The stable region of
It is as large as 21 Oersted.

A description will be given of the fact that the stable area with respect to an external magnetic field during reproduction of the magneto-optical recording medium of the present embodiment having the transfer stabilizing layer 106 is increased.

First, the transfer stable layer 106 is made of a transition metal rich G which is always an in-plane magnetized film from room temperature to the Curie temperature.
A case where a dFeCo film is formed will be described. FIG.
(A) shows a transfer magnetic field generation mechanism in the case where the transfer stabilization layer 106 is a transition metal-rich GdFeCo film that is always an in-plane magnetization film from room temperature to the Curie temperature in the magneto-optical recording medium of the present embodiment. .

FIG. 10A shows a case where a light beam is irradiated near the center of the figure. In the region irradiated with the light beam, the temperature of the recording layer 105 increases, so that the magnetization of the recording layer 105 increases as described with reference to FIG. In this case, since the recording layer 105 is rich in transition metal, the magnetic moment 201 of the transition metal element is changed to the magnetic moment 202 of the rare earth element as shown in FIG.
It is much larger. In a region not irradiated with the light beam, the magnetization of the recording layer 105 is small, and the magnetic moment 201 of the transition metal element is slightly larger than the magnetic moment 202 of the rare earth element.

In this embodiment, the recording layer 105, the magnetization control layer 111, and the transfer stabilization layer 106 are formed adjacent to each other. Exchange coupling works between them. When exchange coupling is working, the magnetic moment 201 of the transition metal element and the magnetic moment 202 of the rare earth element of the recording layer 105, the magnetization control layer 111, and the transfer stabilization layer 106 are oriented so that no interface magnetic wall is generated.

However, near the reproduction temperature, the magnetization control layer 1
In No. 11, a magnetostatic coupling force acts between the transfer stable layer 106 and the recording layer 105 because the temperature is higher than the Curie temperature and the magnetism is lost.

The magnetic moment 201 of the transition metal element is
The orientation is as shown in FIG. The direction of the magnetic moment 202 of the rare earth element is opposite to the direction of the magnetic moment 201 of the transition metal element.
The orientation is as shown by the dotted line in FIG.

Next, the transfer stable layer 106 is a rare-earth-rich GdF that is always an in-plane magnetized film from room temperature to the Curie temperature.
The case where an eCo film is formed will be described. FIG.
(B) shows the transfer magnetic field from the recording layer 105 when the transfer stabilization layer 106 is always formed of a rare-earth-rich GdFeCo film that is an in-plane magnetization film from room temperature to the Curie temperature in the magneto-optical recording medium of the present embodiment. The generation mechanism is shown.

In the case of the rare earth-rich transfer stabilization layer 106, which is always an in-plane magnetization film from room temperature to the Curie temperature, the recording layer 105 and the magnetization control Although exchange coupling acts between the layer 111 and the transfer stable layer 106, a magnetostatic coupling force acts between the transfer stable layer 106 and the recording layer 105 near the reproduction temperature. From this, the direction of the magnetic moment 201 of the transition metal element and the magnetic moment 202 of the rare earth element
Are as shown in FIG. 10 (b).

In the magneto-optical recording medium according to the present embodiment, the recording layer 105 at the center of the mark is magnetically coupled to the transfer stabilizing layer 106, which is an in-plane magnetization film, and this is magnetically coupled to the magnetization of the adjacent mark. The bond works. With such a mechanism, the magnetic flux has a closed magnetic path structure, so that the transfer magnetic field is large even at the center of the mark. Since the transfer magnetic field at the center of the mark is increased, the stable area against the external magnetic field during reproduction is increased.

(Embodiment 4) Next, Embodiment 4 of the present invention will be described with reference to the drawings. FIG.
FIG. 9 is a sectional view showing a configuration of a magneto-optical recording medium according to Embodiment 4 of the present invention. Referring to FIG.
Is a polycarbonate substrate provided with a sample servo for light beam tracking. The track width of the substrate 101 is 0.6 μm.

The magneto-optical recording medium according to the present embodiment is
First, an enhancement layer 102 made of a SiN film is formed, and a reproduction layer 10 made of a GdFeCo film is formed thereon.
3. Reproducing auxiliary layer 110 made of GdFeCr film, SiN
An intermediate layer 104 made of a film, a recording layer 105 made of a TbFeCo film, a magnetization control layer 111 made of a TbFe film are formed, and a nonmagnetic layer 109 made of a SiN film is formed.
This is a configuration in which a transfer stable layer 106 made of an o film is formed, a heat control layer 107 made of an AlTi film, and an overcoat layer 108 made of an ultraviolet curable resin are formed.

After the transfer stable layer 106 is formed,
A similar effect can be obtained by a configuration in which a nonmagnetic layer such as an N film is formed, and the heat control layer 107 is further formed. The perpendicular magnetic anisotropy constant of the transfer stable layer 106 of the present embodiment is 2 × 10 ⁵
erg / cm ³ . The film formation was performed under the same film formation conditions as those of the magneto-optical recording medium according to the first to third embodiments.
It was formed on the substrate 101 by a sputtering method.

In this embodiment, recording and reproduction of signals on and from the magneto-optical recording medium are performed in the same manner as in the first embodiment. Table 6 shows external magnetic field characteristics during reproduction of the magneto-optical recording medium formed in the present embodiment. The mark length was measured at 1.88 μm and 0.47 μm. As in the second embodiment, the transfer stable layer 106 is made of a transition metal-rich G that is an in-plane magnetized film from room temperature to Curie temperature.
A dFeCo film, a GdFeCo film that becomes a perpendicular magnetization film at least near the reproduction temperature, and a rare earth-rich GdFeCo film that is an in-plane magnetization film from room temperature to the Curie temperature were studied.

[0126]

[Table 6]

For comparison, an external magnetic field characteristic during reproduction of a magneto-optical recording medium in which the transfer stabilizing layer 106 is not formed is also shown as Conventional Example 4. The magneto-optical recording medium in which the transfer stabilizing layer 106 is not formed has a configuration in which the transfer stabilizing layer 106 is removed from the configuration of the magneto-optical recording medium of the present embodiment. The stable area against the external magnetic field at the time of reproduction
The region of the magnetic field within 1 dB down from the CN ratio obtained when there is no external magnetic field is shown.

As shown in Table 6, the transfer stable layer 106
The magneto-optical recording medium on which is formed a large stable area against an external magnetic field during reproduction regardless of the mark length. When the mark length is 1.88 μm, the stable area of the conventional example is 42 Oersted, whereas the stable area of the magneto-optical recording medium formed with the transfer stable layer 106 according to the present embodiment is 12 Oersteds.
It is as large as 7-178 Oersteds.

Even in the case of a mark having a short mark length of 0.47 μm, the magneto-optical recording medium formed in the present embodiment having the transfer stable layer 106 is different from the conventional example 2 in which the stable area is 161 Oersted. The stable region of
It is as large as 38 Oersted.

A description will be given of the fact that the stable area against the external magnetic field at the time of reproduction of the magneto-optical recording medium of the present embodiment having the transfer stabilizing layer 106 is increased.

First, the transfer stabilizing layer 106 is made of a transition metal rich G which is an in-plane magnetized film from room temperature to Curie temperature.
A case where a dFeCo film is formed will be described. FIG.
(A) shows a transfer magnetic field generation mechanism in the case where the transfer stabilization layer 106 is a transition metal-rich GdFeCo film that is always an in-plane magnetization film from room temperature to the Curie temperature in the magneto-optical recording medium of the present embodiment. .

FIG. 12A shows a case where a light beam is irradiated near the center of the drawing. In the region irradiated with the light beam, the temperature of the recording layer 105 increases, so that the magnetization of the recording layer 105 increases as described with reference to FIG. In this case, since the recording layer 105 is rich in transition metal, the magnetic moment 201 of the transition metal element is changed to the magnetic moment 202 of the rare earth element as shown in FIG.
It is much larger. In a region not irradiated with the light beam, the magnetization of the recording layer 105 is small, and the magnetic moment 201 of the transition metal element is slightly larger than the magnetic moment 202 of the rare earth element.

In the present embodiment, the magnetic moment is oriented so as to form a closed magnetic circuit structure, and the magnetic moment 201 of the transition metal element of the transfer stable layer 106 has the orientation shown in FIG. . Since the magnetic moment 202 of the rare earth element is opposite to the direction of the magnetic moment 201 of the transition metal element, the magnetic moment 202 has the direction shown by the dotted line in FIG.

Next, the transfer stable layer 106 is a rare-earth-rich GdF which is always an in-plane magnetized film from room temperature to the Curie temperature.
The case where an eCo film is formed will be described. FIG.
(B) shows a transfer magnetic field generation mechanism in the case where the transfer stabilization layer 106 in the magneto-optical recording medium of the present embodiment is always formed of a rare-earth-rich GdFeCo film that is an in-plane magnetization film from room temperature to the Curie temperature.

In the case of the rare earth rich transfer stabilization layer 106 which is always an in-plane magnetization film from room temperature to the Curie temperature, the transfer stabilization layer 106 and the magnetization control layer 111 are formed in the same manner as the transition metal rich transfer stabilization layer 106. Since the magnetostatic coupling works,
The direction of the magnetic moment 201 of the transition metal element and the magnetic moment 202 of the rare earth element are as shown in FIG.

In the magneto-optical recording medium of the present embodiment, the recording layer 105 at the center of the mark is magnetically coupled to the transfer stabilizing layer 106, which is an in-plane magnetized film, and it is magnetically coupled to the magnetization of the adjacent mark. The bond works. With such a mechanism, the magnetic flux has a closed magnetic path structure, so that the transfer magnetic field is large even at the center of the mark. Since the transfer magnetic field at the center of the mark is increased, the stable area against the external magnetic field during reproduction is increased.

Table 7 shows that the thickness of the nonmagnetic layer 109 formed between the magnetization control layer 111 and the transfer stabilization layer 106 of the magneto-optical recording medium in this embodiment is 10 nm,
It shows a stable region with respect to an external magnetic field at the time of reproduction when 0 nm and 50 nm are set.

The thickness of the nonmagnetic layer 109 is 10 nm, 30 n
Even when m and 50 nm are used, the stable region with respect to an external magnetic field during reproduction is large, and the effect of the present invention is apparent.

[0139]

[Table 7]

Embodiment 5 Next, Embodiment 5 of the present invention will be described with reference to the drawings. FIG.
15 is a sectional view showing a configuration of a magneto-optical recording medium according to Embodiment 5 of the present invention. Referring to FIG.
Is a polycarbonate substrate provided with a sample servo for light beam tracking. The track width of the substrate 101 is 0.8 μm.

The magneto-optical recording medium according to the present embodiment comprises a substrate 1
First, an enhancement layer 102 made of a SiN film is formed, and a reproduction expansion layer 112 made of a GdFeCo film, a reproduction layer 103 made of a GdFeCo film,
a reflective layer 113 made of an i-film, a recording layer 105 made of a TbFeCo film, an interface layer 114 made of a GdFeCo film, a transfer stable layer 106 made of a GdFeCo film, a heat control layer 107 made of an AlTi film, This is a configuration in which an overcoat layer 108 made of a cured resin is formed. Note that a similar effect can be obtained by forming a nonmagnetic layer such as a SiN film after forming the transfer stable layer 106 and further forming the heat control layer 107.

In the present embodiment, the interface layer 114 is formed. By laminating the thin interface layer 114, the closed magnetic path structure of the magnetic flux of the recording layer 105 and the transfer stabilization layer 106 can be facilitated.

A method for forming the GdFeCo film serving as the interface layer 114 will be described. The degree of vacuum in the chamber is 2 × 1
0 ^-7 Torr or less, and Ar gas is
× 10 ^-3 Torr is introduced. After introducing Ar gas, interface layer 1
A GdFeCo film of No. 14 was formed. In the present embodiment, the thickness of the GdFeCo film serving as the interface layer 114 is set to 1 nm or 2 nm.

Other films are described in Embodiments 1 to 4.
The film was formed on the substrate 101 by the DC sputtering method under the same film forming conditions as those of the magneto-optical recording medium.

The perpendicular magnetic anisotropy constant of the transfer stabilizing layer 106 of this embodiment is 2 × 10 ⁵ erg / cm ³ .

In this embodiment, recording and reproduction of signals on and from the magneto-optical recording medium are performed in the same manner as in the first embodiment. Table 8 shows the external magnetic field characteristics during reproduction when the thickness of the interface layer 114 is changed in the magneto-optical recording medium formed in the present embodiment. The mark length was measured at 1.88 μm and 0.47 μm.

[0147]

[Table 8]

The stable area against an external magnetic field during reproduction is obtained by applying an external magnetic field to obtain a CN which is obtained when there is no external magnetic field.
The region of the magnetic field within 1 dB down from the ratio is shown.

As shown in (Table 8), the stable area against the external magnetic field during reproduction is large regardless of the mark length. When the mark length is 1.88 μm, the thickness of the interface layer 114 is 1 nm.
Is 130 oersted, interface layer 114
When the film thickness is 2 nm, the stable region is as large as 126 Oe.

A description will be given of the fact that the stable area against the external magnetic field at the time of reproduction of the magneto-optical recording medium of the present embodiment having the transfer stabilizing layer 106 is increased. First, the case where the transfer stable layer 106 is formed from a transition metal-rich GdFeCo film that is an in-plane magnetized film from room temperature to Curie temperature will be described. FIG. 14 shows a mechanism for generating a transfer magnetic field in the magneto-optical recording medium of the present embodiment.

FIG. 14 shows a case where a light beam is irradiated near the center of the figure. In the area irradiated with the light beam, the temperature of the recording layer 105 has risen.
As described above, the magnetization of the recording layer 105 increases. In this case, since the recording layer 105 is rich in transition metal,
As shown in FIG. 14, the magnetic moment 20 of the transition metal element
1 is much larger than the magnetic moment 202 of the rare earth element. In the area where the light beam is not irradiated,
The magnetization of the recording layer 105 is small, and the magnetic moment 201 of the transition metal element is slightly larger than the magnetic moment 202 of the rare earth element.

In this embodiment, since the recording layer 105, the interface layer 114, and the transfer stable layer 106 are formed adjacent to each other, exchange coupling is formed between the recording layer 105, the interface layer 114, and the transfer stable layer 106. work. When exchange coupling is working, the recording layer 105, the interface layer 114, and the transfer stabilizing layer 1
06 of each transition metal element 201
Are oriented so that no interface domain wall is generated. The magnetic moment 201 of the transition metal element shows a direction as shown in FIG.

The magnetic moment 202 of the rare earth element
Is opposite to the direction of the magnetic moment 201 of the transition metal element, and therefore has the direction shown by the dotted line in FIG.

In the magneto-optical recording medium of the present embodiment, the recording layer 105 at the center of the mark is magnetically coupled to the transfer stable layer 106, which is an in-plane magnetized film, and this is magnetically coupled to the magnetization of the adjacent mark. The bond works. With such a mechanism, the magnetic flux has a closed magnetic path structure, so that the transfer magnetic field is large even at the center of the mark. Since the transfer magnetic field at the center of the mark is increased, the stable area against the external magnetic field during reproduction is increased.

In this case, since the interface layer 114 is very thin, the direction of the magnetic moment is not completely in-plane but has a slightly vertical component under the influence of the recording layer 105 which is a perpendicular magnetization film. . As shown in FIG.
5 is a completely perpendicular magnetic film, the transfer stable layer 106 is an in-plane magnetic film, and the interface layer 114 between the recording layer 105 and the transfer stable layer 106 is in an intermediate state between the in-plane magnetic film and the perpendicular magnetic film.

(Embodiment 6) Next, Embodiment 6 of the present invention will be described with reference to the drawings. FIG.
FIG. 9 is a sectional view showing a configuration of a magneto-optical recording medium according to Embodiment 4 of the present invention. Referring to FIG.
Is a polycarbonate substrate provided with a sample servo for light beam tracking. The track width of the substrate 101 is 0.6 μm.

The magneto-optical recording medium according to the present embodiment is
First, an enhancement layer 102 made of a SiN film is formed, and a reproduction layer 10 made of a GdFeCo film is formed thereon.
3. An intermediate layer 104 made of a SiN film, a recording layer 105 made of a TbFeCo film are formed, a transfer stable layer 106 made of a GdFeCo film is further formed, a protective layer 115 made of a SiN film, and an overcoat layer made of an ultraviolet curable resin. 1
08 is formed.

A method for forming the GdFeCo film serving as the transfer stable layer 106 will be described. Reduce the degree of vacuum in the chamber to 2
Ar gas is introduced into the chamber at 5 × 10 ⁻³ Torr at a pressure of × 10 ⁻⁷ Torr or less. After the introduction of the Ar gas, a GdFeCo film serving as the transfer stable layer 106 was formed. In the present embodiment, GdFeC which is the transfer stable layer 106 is used.
The thickness of the o film was set to 15 nm.

In the present embodiment, the composition of the GdFeCo film as the transfer stabilizing layer 106 is changed to Gd _19.0 Fe _72.6
Co _{8.4 (at.%)} , Gd _20.8 Fe _70.8 Co _{8.4 (at.%)} , Gd
_23.0 Fe _68.6 Co _{8.4 (at.%)} .

The transfer stabilizing layer 106 of the present embodiment
The perpendicular magnetic anisotropy is 0.8 × 10^Fiveerg / cm^Threeand
1.2 × 10^Fiveerg / cm^Three, 1.4 × 10^Fiveerg /
cm ^ThreeAnd a single layer becomes a perpendicular magnetization film.

The film thickness of the protective layer 115 is
It is necessary to protect the transfer stable layer 106 from corrosion such as oxidation, so that the thickness was set to 50 nm.

Other films are described in Embodiments 1 to 5.
The film was formed on the substrate 101 by the DC sputtering method under the same film forming conditions as those of the magneto-optical recording medium.

In the present embodiment, recording and reproduction of signals on and from the magneto-optical recording medium were performed in the same manner as in the first embodiment. Table 9 shows the external magnetic field characteristics during reproduction of the magneto-optical recording medium formed in the present embodiment. The mark length was measured at 1.88 μm and 0.47 μm.

[0164]

[Table 9]

For comparison, an external magnetic field characteristic during reproduction of a magneto-optical recording medium in which the transfer stabilizing layer 106 is not formed is also shown as Conventional Example 5. The magneto-optical recording medium in which the transfer stabilizing layer 106 is not formed has a configuration in which the transfer stabilizing layer 106 is removed from the configuration of the magneto-optical recording medium of the present embodiment. The stable area against the external magnetic field at the time of reproduction
The region of the magnetic field within 1 dB down from the CN ratio obtained when there is no external magnetic field is shown.

As shown in Table 9, the transfer stable layer 106
The magneto-optical recording medium on which is formed a large stable area against an external magnetic field during reproduction regardless of the mark length. When the mark length is 1.88 μm, the stable area of Conventional Example 5 is 68 Oersted, whereas the stable area of the magneto-optical recording medium formed with the transfer stable layer 106 according to the present embodiment is 1 Oe.
69 to 187 Oe, which is larger than that of the conventional example 5. In particular, the composition of the transfer stabilizing layer is Gd _20.8 Fe _70.8 Co
_{In the case of 8.4 (at.%)} , The stable region with respect to the reproducing magnetic field is the largest.

Even in the case of a mark having a short mark length of 0.47 μm, the magneto-optical recording medium formed in the present embodiment having the transfer stable layer 106 is different from the conventional example 5 in which the stable area is 120 Oersted. The stable region of 217-2
It is as large as 21 Oersted.

The composition of the transfer stabilizing layer 106 was Gd _20.8 Fe
_{In the case of 70.8} Co _{8.4 (at.%)} , A stable region against an external magnetic field during reproduction is increased, and at the same time, a recording magnetic field applied during recording can be reduced. When recording is performed on a magneto-optical recording medium, a magnetic field is required according to a signal.
Reducing the recording magnetic field can save power. Table 10 shows the magnitude of the CN ratio when recording was performed at 350 Oersted and 150 Oersted recording magnetic fields. For comparison, the CN ratio of Conventional Example 5 without the transfer stabilizing layer 106 is also shown.

In Conventional Example 5, when recording is performed with a recording magnetic field of 150 Oe, the CN ratio deteriorates. On the contrary,
The composition of the transfer stabilizing layer 106 is Gd _20.8 Fe _70.8 Co
_{In the case of 8.4 (at.%)} , Even when recording is performed with a recording magnetic field of 150 Oe, almost the same CN ratio is obtained as when recording is performed with a recording magnetic field of 350 Oe.

[0170]

[Table 10]

If the thickness of the reproducing layer 103 is less than 5 nm, a sufficient reproduced signal cannot be obtained, so that it is preferably 5 nm or more, and more preferably 8 nm or more.

Note that, in the embodiment of the present invention, the reproducing layer 1
GdFeCo having a composition that becomes an in-plane magnetization film at room temperature and a perpendicular magnetization film at high temperature was used for 03. However, even if the reproducing layer 103 has a composition other than that of the above-described embodiment, the in-plane magnetization film and high temperature The same effect can be obtained as long as the characteristic becomes a perpendicular magnetization film.

The reproducing layer 103 includes a rare earth-transition metal alloy other than GdFeCo, for example, GdTbFeCo,
The same effect can be obtained with GdDyFeCo, DyFeCo, and the like, as long as the film becomes an in-plane magnetic film at room temperature and a perpendicular magnetic film at high temperature.

The same effect can be obtained even when Cr or Al or the like is added to the rare earth-transition metal alloy serving as the reproducing layer 103 as long as the film becomes an in-plane magnetic film at room temperature and a perpendicular magnetic film at high temperature. can get.

Note that, in the embodiment of the present invention, the recording layer 1
The 05, the composition of _{Tb 22.1 Fe 71.2 Co 6. 7 (} at.%) T
Although bFeCo was used, the coercive force was large at room temperature,
As long as the film is a perpendicular magnetization film and can hold recorded information, the same effect can be obtained even with a composition other than the above.

In the embodiment of the present invention, the recording layer 1
05, TbFeCo was used, but a rare earth-transition metal alloy other than TbFeCo, for example, DyFeCo, Tb
Similar effects can be obtained with DyFeCo or a noble metal-transition metal, for example, a noble metal-transition metal multilayer film such as Pt / Co or Pd / Co, a noble metal-transition metal alloy such as PtCo or PdCo, or a garnet film.

Even if the recording layer 105 is doped with Cr or Al, the coercive force is large at room temperature.
A similar effect can be obtained as long as the film is a perpendicular magnetization film and can hold recorded information.

In the embodiment of the present invention, the enhancement layer 102, the protection layer 115, the non-magnetic layer 109,
For the intermediate layer 104, SiN was used, but AlN, SiA
Nitride such as 1N film, oxide such as SiO and AlO, Zn
Similar effects can be obtained by using a dielectric layer such as a chalcogen compound such as S or ZnTe.

The heat control layer 107 may be made of a material having a higher thermal conductivity than the magnetic film used in the present invention.
Similar effects can be obtained by using a metal film such as AlCr, Cu, Au, Ag, or Ta, Cr, or the like.

After the formation of the transfer stable layer 106,
A similar effect can be obtained by a configuration in which a nonmagnetic layer such as an N film is formed, and the heat control layer 107 is further formed.

[0181]

As described above, according to the present invention, in a magneto-optical recording medium in which information on a recording layer typified by a CAD disk is transferred to a reproducing layer by magnetostatic coupling force, the information is transferred near the recording layer. By forming the stable layer, the transfer magnetic field generated from the recording layer near the center of the mark can be increased, and a remarkable effect that the stable area against the external magnetic field during reproduction increases.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a magneto-optical recording medium according to a first embodiment of the present invention.

FIGS. 2A and 2B are diagrams showing characteristics of the magneto-optical recording medium according to the embodiment of the present invention. FIG. 2A shows the relationship between the Kerr rotation angle and the external magnetic field at room temperature of the reproducing layer of the present invention. FIG. 5C shows the relationship between the Kerr rotation angle and the external magnetic field at the temperature at which the in-plane magnetization film of the reproducing layer transitions from the in-plane magnetization film to the perpendicular magnetization film. Diagram showing relationships

FIG. 3 shows the perpendicular magnetic anisotropy energy K of the reproducing layer of the present invention.
Diagram showing the relationship between u and demagnetizing field energy 2πMs ² and temperature

FIG. 4 is a diagram showing the relationship between the Kerr rotation angle and the Curie temperature of the reproducing layer of the present invention.

FIG. 5 is a diagram showing the relationship between the saturation magnetization Ms of the recording layer of the present invention and temperature.

6A and 6B are diagrams showing a transfer magnetic field generation mechanism when a transfer stabilizing layer is formed of an Fe film in the magneto-optical recording medium according to the first embodiment of the present invention;

FIG. 7 is a sectional view showing a configuration of a magneto-optical recording medium according to a second embodiment of the present invention.

FIG. 8 is a diagram showing a transfer magnetic field generation mechanism when a transfer metal layer is formed of a transition metal-rich GdFeCo film in the magneto-optical recording medium according to the second embodiment of the present invention; The figure which shows the generation | occurrence | production mechanism of the transfer magnetic field at the time of forming a rare earth rich GdFeCo film | membrane.

FIG. 9 is a sectional view showing a configuration of a magneto-optical recording medium according to a third embodiment of the present invention.

10A and 10B are diagrams showing a transfer magnetic field generation mechanism when a transfer metal layer is formed of a transition metal rich GdFeCo film in the magneto-optical recording medium according to the third embodiment of the present invention. The figure which shows the generation | occurrence | production mechanism of the transfer magnetic field at the time of forming a rare earth rich GdFeCo film | membrane.

FIG. 11 is a sectional view showing a configuration of a magneto-optical recording medium according to a fourth embodiment of the present invention.

12A and 12B are diagrams illustrating a transfer magnetic field generation mechanism when a transfer metal layer is formed of a transition metal-rich GdFeCo film in the magneto-optical recording medium according to the fourth embodiment of the present invention. The figure which shows the generation | occurrence | production mechanism of the transfer magnetic field at the time of forming a rare earth rich GdFeCo film | membrane.

FIG. 13 is a sectional view showing a configuration of a magneto-optical recording medium according to a fifth embodiment of the present invention.

FIG. 14 is a diagram showing a transfer magnetic field generation mechanism in the magneto-optical recording medium according to the fifth embodiment of the present invention.

FIG. 15 is a sectional view showing a configuration of a magneto-optical recording medium according to a sixth embodiment of the present invention.

FIG. 16 is a sectional view showing a configuration of a magneto-optical recording medium according to a conventional mode.

17A and 17B are diagrams showing a transfer magnetic field generation mechanism in a magneto-optical recording medium according to a conventional embodiment. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Substrate 102 Enhancement layer 103 Reproduction layer 104 Intermediate layer 105 Recording layer 106 Transfer stabilization layer 107 Thermal control layer 108 Overcoat layer 109 Nonmagnetic layer 110 Reproduction auxiliary layer 111 Magnetization control layer 112 Reproduction enlargement layer 113 Reflection layer 114 Interface layer 115 Protection Layer 201 Magnetic moment of transition metal element 202 Magnetic moment of rare earth element

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 11/105 511 G11B 11/105 511C 511G 511P 511Q 531 531P 531Q 531V 586 586L

Claims (20)

[Claims] A recording layer having a perpendicular magnetic anisotropy at least at a reproducing temperature; and a recording layer having perpendicular magnetic anisotropy. Information of the recording layer is transferred to the reproducing layer by a magnetostatic coupling force. A magneto-optical recording medium, wherein a transfer stabilizing layer having an exchange coupling force with the recording layer is provided on a side of the recording layer opposite to the reproduction layer. 2. A light having a reproducing layer which becomes a perpendicular magnetization film at least at a high temperature, and a recording layer having a perpendicular magnetic anisotropy, wherein information of the recording layer is transferred to the reproducing layer by magnetostatic coupling force. A magnetic recording medium, wherein a transfer stabilizing layer having a magnetostatic coupling force with the recording layer is provided on a side of the recording layer opposite to the reproduction layer side via a nonmagnetic layer. Magneto-optical recording medium. 3. A magneto-optical recording medium according to claim 1, wherein a transfer stabilizing layer is provided on a side of said recording layer opposite to said reproducing layer via said magnetization control layer. . 4. The magneto-optical recording medium according to claim 1, wherein a transfer stabilizing layer is provided on a side opposite to the reproduction layer side of the recording layer via a thin interface layer. 5. The transfer stability layer has a perpendicular magnetic anisotropy constant of 2 × 1.
^{3. The} magneto-optical recording medium according to claim 1, wherein the magneto-optical recording medium is at most 0 ⁵ (erg / cm ³ ). 6. The magneto-optical recording medium according to claim 1, wherein the transfer stable layer contains at least a transition metal element. 7. The magneto-optical recording medium according to claim 6, wherein the transfer stable layer is a rare earth-transition metal film. 8. The magneto-optical recording medium according to claim 7, wherein the transfer stabilizing layer contains at least Gd. 9. The transfer stable layer having a Gd ratio of 19 to 23 (a
t. %). 10. The transfer stable layer is at least a perpendicular magnetization film in a temperature range from room temperature to Curie temperature.
A magneto-optical recording medium according to claim 1. 11. The magneto-optical recording medium according to claim 1, wherein an intermediate layer, which is a non-magnetic film, is provided between the reproducing layer and the recording layer. 12. The magneto-optical recording medium according to claim 11, wherein the intermediate layer is a dielectric film. 13. A magneto-optical recording medium according to claim 1, wherein a reflection layer capable of reflecting incident light is provided between the reproducing layer and the recording layer. 14. A reflective layer comprising at least Al, Cu, Au,
14. The magneto-optical recording medium according to claim 13, comprising one or more metals from Ag. 15. The magneto-optical recording medium according to claim 1, wherein a reproduction auxiliary layer, which is an in-plane magnetization film, is provided between the reproduction layer and the recording layer. 16. The magneto-optical recording medium according to claim 1, further comprising a reproduction expansion layer for expanding a signal on the light incident side of the reproduction layer. 17. A heat control layer comprising at least Al, Cu, A
3. The magneto-optical recording medium according to claim 1, wherein the medium contains at least one metal from u and Ag. 18. The magneto-optical recording medium according to claim 2, wherein the non-magnetic layer is a dielectric film. 19. The magneto-optical recording medium according to claim 4, wherein the thickness of the interface layer is 2 nm or less. 20. Magneto-optical recording, comprising: a reproducing layer that becomes a perpendicular magnetic film at least at a reproducing temperature; and a recording layer having perpendicular magnetic anisotropy, wherein information of the recording layer is transferred to the reproducing layer by a magnetostatic coupling force. A reproducing method for a magneto-optical recording medium for reproducing information by irradiating a medium with a light beam to magnetically couple the information recorded on the recording layer with the reproducing layer and the recording layer, A reproducing method for a magneto-optical recording medium, wherein a transfer stabilizing layer provided on a side opposite to the reproducing layer side of the layer reproduces the recording layer with a magnetic coupling force.