JP3418088B2 - Magneto-optical recording medium and reproducing method of magneto-optical recording medium - 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 such as a magneto-optical disk, a magneto-optical tape, a magneto-optical card and a method of reproducing the magneto-optical recording medium applied to a magneto-optical recording / reproducing apparatus.
It is about law .

[0002]

2. Description of the Related Art Conventionally, a magneto-optical recording medium has been put into practical use as a rewritable optical recording medium. In such a magneto-optical recording medium, the recording bit diameter, which is a recording magnetic domain, and the recording bit interval are smaller than the beam diameter of the light beam emitted from the semiconductor laser focused on the magneto-optical recording medium. Then, there is a drawback that the reproduction characteristics are deteriorated.

[0003] Such a drawback is that, since adjacent recording bits are within the beam diameter of the light beam focused on the target recording bit, it becomes impossible to reproduce each recording bit separately. That is the cause.

In order to solve the above-mentioned drawbacks, Japanese Patent Laid-Open No. 6-
In JP-A-131733 and JP-A-8-221824, a magneto-optical recording comprising a two-layer magnetic film in which a recording layer formed of a perpendicular magnetization film and a reproducing layer having a Curie temperature lower than the Curie temperature of the recording layer are exchange-coupled to each other. A super-resolution reproduction technique using a medium has been proposed. As a result, the recorded magnetic domain information of the portion where the temperature rises above the Curie temperature of the reproducing layer is masked, and even when adjacent recording bits enter within the focused light beam diameter, individual recording bits are separated and reproduced. It has been shown that it is possible to do.

[0005]

However, the above-mentioned JP-A-6-131733 and JP-A-8-22 have been proposed.
In Japanese Patent No. 1824, in a perpendicular magnetization film made of a rare earth-transition metal alloy as a reproducing layer, TbFe, TbFeCo, containing Tb or Dy as a rare earth metal,
DyFe, DyFeCo, TbDyFeCo, GdTb
The same material as the recording layer such as Fe is used. Perpendicular magnetic films made of rare earth-transition metal alloys using Tb or Dy as the rare earth metal have large perpendicular magnetic anisotropy. Therefore, in the recording / reproducing operation, due to the leakage flux generated from the recording layer and the reproducing layer. Since the random magnetization state is fixed in the reproducing layer, it is difficult to stably realize a good recording / reproducing operation. This is a problem because both the reproducing layer and the recording layer are made of a material having a large perpendicular magnetic anisotropy.

Further, as another problem, since the Curie temperature of the reproducing layer becomes low, the Kerr rotation angle of the reproducing layer becomes small and the reproduced signal also becomes small.

The present invention has been made to solve the above-mentioned conventional problems, and an object thereof is a two-layer magnetic film exchange-coupled with a reproducing layer having a Curie temperature lower than the Curie temperature of the recording layer. In a super-resolution reproducing technology using a magneto-optical recording medium consisting of, it is possible to transfer the magnetization state of the recording layer to the reproducing layer as it is, and realize a stable recording and reproducing operation, and a reproducing layer with a low Curie temperature. possible to obtain a sufficiently large reproduction signal even with a magneto-optical recording medium capable of realizing a stable super-resolution reproduction and optical
It is to provide a reproducing method of a magnetic recording medium .

[0008]

The present invention for achieving the above object is as follows. (1) The magneto-optical recording medium according to claim 1 is a perpendicular magnetization film.
Recording layer consisting of a layer and a key lower than the Curie temperature of the recording layer.
Two-layer structure in which a reproducing layer having a Curie temperature is exchange-coupled
In a magneto-optical recording medium having a magnetic layer, the reproducing layer is G
dFeD or GdFeCoD (D is Y, Ti,
Element selected from V, Cr, Pd, Cu, Al, Si
Elemental or alloy consisting of two or more of these elements)
It consists of According to this configuration, as the reproduction layer
The perpendicular magnetic anisotropy is much higher than that of TbFe or DyFe.
Use materials containing small amounts of GdFe and GdFeCo
Is possible, and in this super resolution reproduction technology, the recording layer
Stable because the magnetization state can be directly transferred to the reproducing layer
It is possible to realize the super-resolution reproduction. GdFe, G
dFeCo has conventionally been used as a reproducing layer of a magneto-optical recording medium.
Although it was used, the Curie temperature of Gd is Tb or
Higher than Curie temperature of Dy, resulting in GdF
The Curie temperature of e and GdFeCo increases. Book super-resolution
In the case of regeneration technology, the Curie temperature is higher than that of the regeneration layer.
Recording sensitivity is significantly deteriorated because it is necessary to use recording layers
However, it becomes impractical. The present inventor
Small perpendicular magnetic anisotropy consisting of Fe or GdFeCo
Y, Ti, V, Cr, Pd, Cu, A
element selected from l and Si, or two of them
By including an alloy consisting of more than one element, G
Effectively lowers the Curie temperature of dFe or GdFeCo
Discover that it is possible to
Good use as a super-resolution magneto-optical recording medium when used as a green layer
The recording / reproducing characteristics could be obtained. (2) The magneto-optical recording medium according to claim 2 is a perpendicular magnetization film.
Recording layer consisting of a layer and a key lower than the Curie temperature of the recording layer.
Two-layer structure in which a reproducing layer having a Curie temperature is exchange-coupled
In a magneto-optical recording medium having a magnetic layer, the reproducing layer is G
dHRFe or GdHRFeCo or Gd
HRFeD or GdHRFeCoD (HR is T
an element selected from b, Dy, Ho, Er, or
Alloy consisting of two kinds or more elements, D is Y, T
selected from i, V, Cr, Pd, Cu, Al, Si
Element, or a combination of two or more of these elements
Money). According to this configuration, as in (1),
As a layer, the perpendicular magnetic anisotropy is higher than that of TbFe or DyFe.
Uses materials containing extremely small GdFe and GdFeCo
It is possible to do this.
It is possible to transfer the magnetization state of the recording layer to the reproducing layer as it is.
It is possible to realize stable super-resolution reproduction. (1)
In GdFe or GdFeCo represented by D
GdFe or GdF by containing the element
Effectively lowering the Curie temperature of eCo for super-resolution magneto-optical recording
Good recording and reproducing characteristics were obtained as a recording medium.
Element selected from genus Tb, Dy, Ho, Er
Element or an alloy consisting of two or more of these elements
By including in GdFe or GdFeCo
Also affects the Curie temperature of GdFe or GdFeCo
Can be lowered and super-resolution magneto-optical recording
According to the present invention, good recording / reproducing characteristics can be obtained as a medium.
Discovered, and further, Y, Ti, V, Cr, Pd, C
elements selected from u, Al, Si, or those
An alloy composed of two or more elements of GdFe or Gd
Even when it is contained in FeCo, GdFe or
Can effectively lower the Curie temperature of GdFeCo
And is a good recording medium for super-resolution magneto-optical recording media.
Recording / playback characteristics can be obtained. (3) The magneto-optical recording medium according to claim 3 is a perpendicular magnetization film.
Recording layer consisting of a layer and a key lower than the Curie temperature of the recording layer.
Two-layer structure in which a reproducing layer having a Curie temperature is exchange-coupled
In a magneto-optical recording medium having a magnetic layer, the reproducing layer is G
dLRFe or GdLRFeCo or Gd
LRFeD or GdLRFeCoD (LR is C
an element selected from e, Pr, Nd, and Sm, or
Alloy consisting of two or more of these elements, D is Y, T
selected from i, V, Cr, Pd, Cu, Al, Si
Element, or a combination of two or more of these elements
Money). According to this configuration, (1)
Similarly, as the reproducing layer, the perpendicular magnetic anisotropy is TbFe or D.
Contains GdFe and GdFeCo which are much smaller than yFe.
This super resolution reproduction technology is now possible.
In, it is transferred directly to the reproducing layer magnetization state of the recording layer
It is possible to realize stable super-resolution reproduction that can
Wear. In (1), D is added to GdFe or GdFeCo.
By including the element represented by GdFe or
Effectively lowering the Curie temperature of GdFeCo
It has good recording and reproducing characteristics as an aerial recording medium.
Selected from Ce, Pr, Nd and Sm which are metal
Element or alloy consisting of two or more of these elements
By containing GdFe or GdFeCo
However, the Curie temperature of GdFe or GdFeCo is effective.
It is possible to reduce the result and super resolution magneto-optical recording.
Good recording and reproducing characteristics can be obtained as a recording medium. further,
From Y, Ti, V, Cr, Pd, Cu, Al, Si
Selected element, or two or more of these elements
Alloy containing GdFe or GdFeCo
Curie of GdFe or GdFeCo even in the case of
The temperature can be effectively lowered, and the super-resolution magneto-optical
Good recording and reproducing characteristics were obtained as a recording medium. (4) The magneto-optical recording medium according to claim 4 is a magneto-optical disk.
A transparent dielectric protective layer, a reproducing layer, a recording layer, and a protective layer on the disk substrate.
The protective layer is formed in sequence. With this configuration
For example, the transparent dielectric protection formed on the magneto-optical disk substrate side
Improved super-resolution reproduction characteristics due to optical interference effect of layers
It is possible to use the protective layer and the reproduction layer.
The recording layer is shielded from the outside air and protected from deterioration such as oxidation.
It is possible to (5) The magneto-optical recording medium according to claim 5 is the magneto-optical recording medium according to claim 1.
The magneto-optical recording medium according to claim 4.
The thickness of the recording layer is 5 nm or more, and the reproduction is performed.
For the recording layer having a layer thickness of 10 nm or more, as the reproducing layer
Has a reflective layer on the opposite side, and the film thickness of the reproducing layer and the recording layer
Is 15 nm or more and 45 nm or less.
According to this structure, the two-layer magnetic layer (recording layer and reproducing layer
The laser light transmitted through the (layer) is reflected by the reflective layer.
It is possible to increase the car rotation angle by utilizing the multiple interference effect.
This makes it possible to improve the super-resolution reproduction characteristic. sand
That is, in the present invention, the temperature is higher than the Curie temperature of the recording layer.
Assuming that a regeneration layer with a low Curie temperature is used
And the Kerr rotation angle of the playback layer itself is extremely small.
It Therefore, the reproduction resolution is high, but the reproduction signal strength is small.
It has the drawback of becoming less . Therefore, with a reflective layer
In addition, the multiple interference effect in the magneto-optical recording medium is used.
By increasing the car rotation angle,
Super-resolution playback with high resolution and high playback signal strength
It can be realized. (6) The magneto-optical recording medium according to claim 6 is the same as that according to claim 5.
In the magneto-optical recording medium described above, the thickness of the recording layer is 5 nm.
And the thickness of the reproducing layer is 10 nm or more.
There is something. According to this structure,
In the magneto-optical recording medium having the structure, the thickness of the recording layer and the reproducing layer
Is optimized, and good super-resolution reproduction characteristics can be obtained.
Becomes That is, in claim 5, the incident ray
The light is the laser light reflected on the reproducing layer and the recording on the reproducing layer.
Recording layer.
And the laser light transmitted through the reproducing layer and the reproducing layer are detected as reproducing light.
Will be. That is, the magnetization information of the recording layer is also to some extent
Will be played. Originally, in super-resolution reproduction,
By reproducing only the reflected laser light from the reproducing layer,
It is also possible to obtain a high reproduction resolution.
The recording layer thickness is 5 nm or more, and the reproducing layer thickness is 10 nm.
By the above, playback resolution is high and playback is
It is possible to realize super-resolution reproduction with high signal strength.
It (7) The magneto-optical recording medium according to claim 7 is the same as in claim 5.
Or the magneto-optical recording medium according to claim 6,
On the disk substrate, the transparent dielectric protective layer, the reproducing layer, the front
A recording layer, a transparent dielectric protective layer, and the reflective layer are sequentially formed.
It is something that is. With this configuration, the magneto-optical disk
Optical protection by a transparent dielectric protective layer formed on the substrate side.
It is possible to improve the super-resolution reproduction characteristics by the interference effect.
In addition, the reproduction layer and the recording layer are shielded from the outside air by
It is possible to protect from deterioration such as deterioration. (8) The magneto-optical recording medium according to claim 8,
The magneto-optical recording medium according to any one of 2, 3, 5, 6
And has an in-plane magnetization state at room temperature, and at least the recording layer
The recording auxiliary layer that becomes perpendicularly magnetized at the Curie temperature
It is formed by magnetostatically coupling with the recording layer. this
According to the configuration, the perpendicular magnetization at the Curie temperature of the recording layer
The leakage magnetic field generated from the recording auxiliary layer
A smaller recording magnetic field by orienting in the same direction as the magnetic field
It is possible to record at. (9) The reproducing method of the magneto-optical recording medium according to claim 9,
It depends on the recording layer consisting of perpendicularly magnetized film and the Curie temperature of the recording layer.
Exchange-coupled with a regeneration layer having a lower Curie temperature
For reproducing a magneto-optical recording medium having a two-layer magnetic layer
And the reproducing layer has an in-plane magnetization state at room temperature.
Is a perpendicular magnetization state at a temperature above the critical temperature.
A magnetic film for reproducing the recording medium as it moves.
By irradiating the laser beam, the light beam spot
Rear mask in which the magnetization of the reproducing layer disappears or decreases in the rear
It is characterized by forming a region. According to this configuration,
High resolution due to the formation of the rear mask area
Super-resolution reproduction is possible. The magneto-optical recording according to claim 9.
The medium is the magneto-optical recording medium according to claim 8,
Transparent dielectric protective layer on the magnetic disk substrate
Layer, the recording layer, the non-magnetic layer, the recording auxiliary layer, the protective layer
It is formed sequentially. According to this configuration, the light
The transparent dielectric protective layer formed on the magnetic disk substrate side
The super-resolution reproduction characteristics can be improved by the optical interference effect
In addition to the above, the protective layer protects the reproducing layer and the recording layer.
And are shielded from the outside air and protected from deterioration such as oxidation.
Is possible. Further, a non-magnetic layer is used as a recording layer and a recording auxiliary layer.
Between the recording layer and the recording auxiliary layer by being formed between
It is possible to realize a stable magnetostatic coupling state,
The recording magnetic field can be stably reduced. Also non-magnet
The recording layer is a transparent dielectric layer and the recording auxiliary layer is a reflective layer.
If it is also used as, the super-resolution due to the optical interference effect
It is possible to improve the playback characteristics, and
By forming an electric layer between the recording layer and the recording auxiliary layer,
The stable magnetostatic coupling between the recording layer and the recording auxiliary layer.
Can be realized and the recording magnetic field can be reduced stably.
can do. (10) The reproducing method of the magneto-optical recording medium according to claim 10.
Is the recording layer composed of the perpendicular magnetization film and the Curie temperature of the recording layer.
Exchange-coupled with the regeneration layer, which has a Curie temperature below 100 degrees
Reproduction of a magneto-optical recording medium having a two-layer magnetic layer
The reproducing layer has an in-plane magnetization at room temperature.
Is a state and is in a perpendicular magnetization state at a temperature above the critical temperature.
It is a magnetic film that becomes
By irradiating a laser beam for
The rear rim where the magnetization of the reproducing layer disappears or decreases behind
It forms a mask area. According to this configuration,
It becomes possible to realize super-resolution reproduction with high resolution. (11) A method of reproducing a magneto-optical recording medium according to claim 11.
Is a reproducing layer for the magneto-optical recording medium according to claim 10.
The optical beam for reproduction is incident from the side, and the magneto-optical recording is performed.
The recording medium temperature is higher than the Curie temperature of the reproducing layer.
It is regenerated by raising the temperature below the Curie temperature of the layer.
is there. With this configuration, high-resolution super-resolution reproduction is realized.
It becomes possible to manifest.

[0009]

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[0025]

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[0032]

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

First, the reproducing operation principle of the magneto-optical recording medium of the present invention will be described. FIG. 1 is a plan view for explaining the super-resolution reproducing operation principle of the magneto-optical recording medium of the present invention, and FIG. 2 is a sectional view for explaining the super-resolution reproducing operation principle of the magneto-optical recording medium of the present invention. is there.

In the magneto-optical recording medium of the present invention, as shown in FIG. 2, the recording layer 7 made of a perpendicularly magnetized film and the reproducing layer 6 having a Curie temperature lower than the Curie temperature of the recording layer 7 are exchange-coupled. It has a structure composed of a two-layer magnetic layer.

The magneto-optical recording medium is focused and irradiated with the laser beam 5 for recording and reproduction. When the recording medium is moved (disk rotation), the laser beam is irradiated, so that the recording medium is irradiated with the light beam. There is a high temperature area behind the spot 1. Here, the reproduction layer 6 is formed by the laser beam 5.
When the temperature is raised above the Curie temperature (and below the Curie temperature of the recording layer 7), the rear mask region 2 is formed in the reproducing layer 6.

The rear mask region 2 is a region where the temperature of the magneto-optical recording medium is equal to or higher than the Curie temperature of the reproducing layer 6, and the magnetization of the reproducing layer 6 in this region disappears or decreases. Therefore, the signal reproduction by the polar Kerr effect is not performed, the recording information 4 located in the rear of the light beam spot 1 is not reproduced, and only the recording information 3 located in the front of the light beam spot 1 is reproduced. Become.

As described above, in the magneto-optical recording medium of the present invention, the rear mask region 2 is formed even when high density recording is performed such that a plurality of recording magnetic domains are formed in the light beam spot 1. Therefore, it is possible to reduce a substantial reproduction area and reproduce each magnetic domain, that is, it is possible to realize super-resolution reproduction.

[First Embodiment] The first embodiment of the present invention will be described below with reference to the drawings. In this embodiment, a case where a magneto-optical disk is applied as the magneto-optical recording medium will be described.

The magneto-optical recording medium of the present invention, as shown in FIG. 3, has a transparent dielectric protective layer 9 on a magneto-optical disk substrate 8.
The reproduction layer 6, the recording layer 7, and the protective layer 10 are sequentially formed.

In such a magneto-optical disk, the Curie temperature recording method is used as the recording method, and the light beam 5 emitted from the semiconductor laser is focused on the reproducing layer 6 and the recording layer 7, and the recording layer 7 is recorded. The recording is performed by controlling the magnetization direction of the recording layer 7 by increasing the temperature above the Curie temperature and applying an external magnetic field.
In reproduction, the same light beam is set to have a weaker power than during recording, and information is reproduced by a magneto-optical effect known as a polar Kerr effect. The polar Kerr effect is a phenomenon in which the direction of rotation of the polarization plane of reflected light is reversed due to the direction of magnetization perpendicular to the light incident surface.

The substrate 8 is made of a transparent base material such as polycarbonate, is formed in a disk shape, and has a guide groove or the like on the film forming surface.

The transparent dielectric protective layer 9 is made of AlN, SiN,
It is desirable to use a transparent dielectric such as AlSiN or Ta ₂ O ₃ , and its film thickness is set so that a good interference effect is realized with respect to the incident light beam 5 and the polar Kerr rotation angle of the medium is increased. When the wavelength of the light beam 5 is 1, and the refractive index of the transparent dielectric protective layer 9 is n, the film thickness of the transparent dielectric protective layer 9 is set to about (l / (4n)). It For example, when the wavelength of the light beam 5 is 680 nm, the film thickness of the transparent dielectric protective layer 9 may be set to about 40 nm to 100 nm.

The reproducing layer 6 has a Curie temperature lower than that of the recording layer 7 and a perpendicular magnetic anisotropy smaller than that of the recording layer 7, and in the non-laminated state with the recording layer 7, from the room temperature to the Curie temperature. An alloy thin film whose main component is a rare earth-transition metal alloy having a coercive force smaller than the coercive force of the recording layer, and the film thickness is set in the range of 20 to 80 nm. When the thickness of the reproducing layer 6 is thinner than 20 nm, a good rear mask effect cannot be obtained, and when the thickness of the reproducing layer 6 is thicker than 80 nm, the recording sensitivity is significantly deteriorated due to the increase of the thickness.

The recording layer 7 is composed of a perpendicular magnetization film made of a rare earth transition metal alloy, and its film thickness is set in the range of 5 nm to 80 nm. When the film thickness of the recording layer 7 is thinner than 5 nm, it becomes difficult to form the recording layer 7 with good reproducibility. When the film thickness of the recording layer 7 is thicker than 80 nm, the recording sensitivity is significantly deteriorated due to the increase of the film thickness. come.

The protective layer 10 is made of AlN, SiN, AlSi.
Transparent dielectric such as N, Ta ₂ O ₃ or Al, Ti, T
It is made of a non-magnetic metal alloy made of a metal such as a or Ni, and is formed for the purpose of preventing oxidation of the rare earth transition metal alloy used for the reproducing layer 6 and the recording layer 7, and has a film thickness of 5 n.
It is set in the range of m to 60 nm.

Further, in some cases, an ultraviolet curable resin, a thermosetting resin or a lubricating layer may be formed on the protective layer 10.

Next, a specific example of the method of forming the magneto-optical disk and the recording / reproducing method of this structure will be described.

(1) Method for forming magneto-optical disk A method of forming the magnetic disk having the above structure will be described.

First, a disk-shaped polycarbonate substrate 8 having pregrooves and prepits is placed in a sputtering apparatus equipped with an Al target, a GdFeY alloy target, and a TbFeCo alloy target, respectively. Then, the inside of the sputtering device is set to 1 × 10 ⁻⁶ T
After evacuating to orr, a mixed gas of argon and nitrogen was introduced, and power was supplied to the Al target to change the gas pressure to 4
Under the condition of × 10 ^-3 Torr, the transparent dielectric protective layer 9 made of AlN is formed on the substrate 8 to have a film thickness of 80 nm.

Then, the inside of the sputtering apparatus is again set at 1 × 10 ^-6.
After evacuating to Torr, argon gas was introduced, and electric power was supplied to the GdFeY alloy target to form (Gd _0.25 Fe) on the transparent dielectric protective layer 9 under the gas pressure of 4 × 10 ⁻³ Torr. _A reproducing layer 6 made of _0.75 ) _0.92 Y _0.08 is formed with a film thickness of 40 nm. The reproducing layer 6 is a perpendicular magnetization film having a coercive force of 8 kA / m at 25 ° C. in a non-laminated state with the recording layer 7, and its Curie temperature is 16
It was 0 ° C.

Then, electric power was supplied to the TbFeCo alloy target, and the recording layer 7 made of Tb _0.25 (Fe _0.88 Co _0.12 ) _0.75 was formed on the reproduction layer 6 under the gas pressure of 4 × 10 ^-3 Torr. It is formed with a film thickness of 40 nm. The recording layer 7 was in a non-laminated state with the reproducing layer 6 and had a compensation temperature of 25 ° C. and a Curie temperature of 240 ° C.

When the reproducing layer 6 and the recording layer 7 are compared in a non-laminated state, the perpendicular magnetic anisotropy of the reproducing layer 6 is smaller than the perpendicular magnetic anisotropy of the recording layer, and the coercive force of the reproducing layer 6 is small. Is
From 25 ° C. to its Curie temperature, the value was always smaller than the coercive force of the recording layer 7.

Next, a mixed gas of argon and nitrogen was introduced,
Electric power is supplied to the Al target, and the gas pressure is 4 × 10 ⁻³ T
Under the condition of orr, the protective layer 10 made of AlN is formed with a film thickness of 20 nm on the recording layer 7.

(2) Recording / reproducing characteristics The magneto-optical disk formed as described above is recorded at a wavelength of 68.
The mark length dependence of CNR (signal to noise ratio) measured by an optical pickup using a 0 nm semiconductor laser is shown in Example 1.
As shown in FIG. In this measurement, the linear velocity was 5 m / s,
The reproduction power was set to 2.5 mW.

For comparison, a CNR when a recording layer having the same composition as that of the recording layer 7 of Example 1 was formed to 80 nm without providing a reproducing layer was taken as Comparative Example 1, and a perpendicular to the same extent as the recording layer 7 was taken as a reproducing layer. Curie temperature 160 ° C. with magnetic anisotropy
CNR in the case of using bFe is shown in the same figure as Comparative Example 2. Further, the mark length dependency of CNR shown here is a signal of a reproduction signal when a recording magnetic domain having a length corresponding to the mark length is continuously formed by a magnetic field modulation recording method at a pitch twice as long as the mark length. It represents the noise-to-noise ratio.

Comparing Example 1 with Comparative Example 1, the CNR of Comparative Example 1 is large in the range of the mark length of 500 nm or more, and the CNR of Example 1 is large in the range of the mark length of 500 nm or less. I understand. This is interpreted as follows.

When the mark length is long, the rear mask is formed in the first embodiment, the reproduction signal is scraped, and the carrier level of the reproduction signal is lowered.
CNR is smaller than that of Comparative Example 1. on the other hand,
When the mark length is short, the rear mask is formed in the first embodiment, and the resolution is improved.
R is larger than that in Comparative Example 1.

Comparing the CNRs of both at a mark length of 300 nm, the CNR of Comparative Example 1 is 5 dB and reproduction is quite difficult, whereas the CNR of Example 1 is 40 dB, which is a sufficiently reproducible CNR. I was able to.

Next, comparing Comparative Example 2 with Example 1 and Comparative Example 1, in Comparative Example 2, as in Example 1, in the long mark length range, the carrier level was lowered due to the mask formation. The CNR is lower than that of Example 1. In Example 1, by realizing super-resolution reproduction, it was possible to maintain a high CNR even in a short mark length, but in Comparative Example 2, at a short mark length, it was sharper than in Example 1. CN
C is low at a mark length of 400 nm.
Is 42 dB in Example 1, whereas it is 29 dB in Comparative Example 2, which is considerably small. This is because, in Comparative Example 2, TbFe having the same perpendicular magnetic anisotropy as that of the recording layer 7 was used as the reproducing layer. Random magnetization state is fixed,
It is considered that this is because it is difficult to stably realize a good recording / reproducing operation. Even if the Curie temperature is the same, by using the reproducing layer 6 made of GdFeY having a smaller perpendicular magnetic anisotropy than the recording layer 7 as in Example 1, a random magnetization state is not fixed in the reproducing layer, It is possible to realize a magneto-optical disk capable of stably realizing a good recording / reproducing operation even with a short mark length.

Next, in the magneto-optical recording medium of the present embodiment, the results of examining the recording / reproducing characteristics by changing the material and composition of the reproducing layer 6 will be shown.

In the first embodiment, (Gd
_0.25 Fe _{0.75) 0.92} but describes results obtained by using the reproducing layer 6 of thickness 40nm made of Y _0.08, and the same 40nm film thickness of the reproduction layer 6, the composition (Gd _A F
e _1-A ) _B Y _1-B was measured in the same manner by changing the values of A and B (atomic ratio).
R is shown in Table 1. Here, in the CNR measurement, the reproduction power was adjusted and measured so that the largest CNR was obtained. Table 1 also shows the Curie temperature (Tc) of each reproducing layer 6.

[0063]

[Table 1]

Here, when the CNR (29 dB) at the mark length of 400 nm in Comparative Example 1 is compared with the CNR of the magneto-optical disk prototyped here, 0.15 ≦ A ≦ 0.3.
A CNR larger than that of Comparative Example 1 was obtained in the range of 3 and 0.80 ≦ B ≦ 0.97. A = 0.10
And A = 0.35, the reproduction layer 6 becomes in-plane magnetized, and reproduction using the magneto-optical effect cannot be performed, so that a reproduction signal cannot be obtained and the CNR becomes zero. Also, B = 0.75
In Comparative Example 1, since the Curie temperature becomes too low, the polar Kerr rotation angle of the reproducing layer 6 itself becomes small and the reproducing signal becomes small, and by forming a wider rear mask region, the reproducing signal becomes smaller. C
Only CNR lower than NR can be obtained. And B
= 1.00, the Curie temperature of the reproducing layer 6 is 22.
Since it becomes 0 ° C. and the difference from the Curie temperature of the recording layer 7 is 240 ° C., it becomes difficult to form a good rear mask, and only the same CNR as in Comparative Example 1 can be obtained.

From the above results, when the composition of the reproducing layer 6 is (Gd _A Fe _1-A ) BY _1-B in the present embodiment,
A and B are 0.15 ≦ A ≦ 0.33 and 0.80
It can be seen that the range needs to be ≦ B ≦ 0.97.
Further, when the Curie temperature of the recording layer 7 is 240 ° C., the Curie temperature of the reproducing layer 6 is 105 ° C. or higher and 200 ° C.
It turns out that it must be:

Next, in Table 1, when B = 0.92, A = A is larger than CNR when A = 0.25.
CNR is 1 when 0.28, 0.30, 0.33
It can be seen that it is increased by ~ 2 dB.

This is A = 0.28, 0.30, 0.3
In the case of 3, the reproducing layer 6 is in-plane magnetized at room temperature and becomes perpendicularly magnetized as the temperature rises. Therefore, the reproduction layer 6 is in-plane magnetized together with the rear mask region 2 described in FIGS. This is because the reproduction resolution is further improved by forming the front mask by the magnetization mask.

This improvement in reproduction resolution will be described in more detail with reference to FIG. FIG. 5 shows a state during reproduction when a recording magnetic domain is formed with a mark length and a mark pitch shorter than those in FIG. When recording is performed with such a short mark length and mark pitch, even if the reproduction resolution is improved only by the rear mask area 2 as shown in FIG. Since the information of the reproducing layer 6 transferred from the recording magnetic domain comes in, it becomes impossible to reproduce the information separately. However, here, by using the reproducing layer 6 which is in the in-plane magnetization state at room temperature and becomes in the perpendicular magnetization state as the temperature rises, the front mask region 11 is formed by the in-plane magnetization mask, and the reproduction resolution is further improved. Will be done.

In this way, A = 0.28,0.3
When it is set to 0, 0.33, the CNR can be increased by 1 to 2 dB as compared with the case of A = 0.25.

Up to this point, the case where GdFeY is used as the reproducing layer 6 in the first embodiment has been described, but in the reproducing layer 6 made of (Gd _0.25 Fe _0.75 ) _0.92 D _0.08 , D is other than Y. Even when the element of is used, it is possible to form the rear mask region 2 in the same manner and obtain similar super-resolution reproduction characteristics. T instead of Y
i, V, Cr, Pd, Cu, Al, Si, Al _0.5 Si
Curie temperature Tc of the reproducing layer 6 formed using _0.5 alloy
Table 2 shows the CNR at a mark length of 400 nm obtained in a magneto-optical disk using the reproducing layer 6.

[0071]

[Table 2]

In each of the magneto-optical disks, a CNR similar to that in Example 1 was obtained, and instead of Y,
Ti, V, Cr, Pd, Cu, Al, Si, Al _0.5 S
By using an element or alloy such as i _0.5 alloy, it is possible to obtain the super-resolution reproduction characteristics similar to those of the first embodiment. Further, even when these elements and alloys are used as D, Gd and Fe are used in the same manner as when Y is used.
It is possible to realize the reproducing layer 6 which is in-plane magnetized at room temperature and becomes perpendicularly magnetized as the temperature rises by adjusting the composition ratio of the masks of both the rear mask and the front mask. It is possible to realize a utilized magneto-optical recording medium having a higher reproduction resolution.

Next, the result when GdFeCo is used as the reproducing layer 6 as a material having a small perpendicular magnetic anisotropy like GdFe will be described. In Table 3, the thickness of the reproducing layer 6 is set to 40 nm, and the composition thereof is (Gd _A (Fe _0.95 Co
_0.05 ) _1-A ) _B Y _1-B was measured in the same manner by changing the values of A and B (atomic ratio), and C at a mark length of 400 nm.
It shows NR.

[0074]

[Table 3]

Here, in the CNR measurement, the reproduction power was adjusted so that the largest CNR was obtained. Table 3 also shows the Curie temperatures (Tc) of the respective reproduction layers 6. Here, Comparative Example 1
Comparing the CNR (29 dB) at the mark length of 400 nm with the CNR of the magneto-optical disk prototyped here,
0.15 ≦ A ≦ 0.33 and 0.70 ≦ B ≦ 0.9
In the range of 0, a CNR larger than that of Comparative Example 1 is obtained. When A = 0.10 and A = 0.35, the reproduction layer 6 becomes in-plane magnetized and reproduction using the magneto-optical effect cannot be performed, and a reproduction signal cannot be obtained and the CNR becomes zero.
Further, at B = 0.65, the Curie temperature becomes too low, the polar Kerr rotation angle of the reproducing layer 6 itself becomes small, the reproducing signal becomes small, and a wider rear mask region is formed, so that the reproducing signal becomes larger. Becomes smaller, and only a CNR lower than that of Comparative Example 1 can be obtained. And when B = 0.95 and B = 1.00,
The Curie temperature of the reproducing layer 6 is the Curie temperature of the recording layer (24
0 ° C.), the same CNR as in Comparative Example 1
It turns out that you can only get it.

From the above results, in the present embodiment, the composition of the reproducing layer 6 is (Gd _A (Fe _0.95 Co _0.05 ) _1-A ) _B Y _1-B
In case of, it is understood that A and B need to be in the range of 0.15 ≦ A ≦ 0.33 and 0.70 ≦ B ≦ 0.90. Here, the ratio of FeCo is (Fe _0.95 Co
_Although the reproduction characteristics are investigated by fixing it to _0.05 ), similar super-resolution reproduction can be realized even when FeCo having a composition ratio other than this is used. However, Co
In a composition containing a large amount of Y, the Curie temperature becomes high, so that it is necessary to add a larger amount of Y.

Next, in Table 3, when B = 0.85, A = 0.2 rather than the CNR when A = 0.25.
CNR of 2 to 3d when set to 8, 0.30 and 0.33
You can see that B is getting higher. This is A = 0.2
In the case of 8, 0.30 and 0.33, the reproducing layer 6 is in-plane magnetized at room temperature, and becomes perpendicularly magnetized with increasing temperature (see FIG. 5).
This is because the reproduction resolution was further improved by forming the front mask of the in-plane magnetization mask together with the rear mask region 2 as in the case of using FeY.

Although the case where GdFeCoY is used as the reproducing layer 6 in the first embodiment has been described above, (Gd _0.25 (Fe _0.95 Co _0.05 ) _0.75 )
_{In the} reproducing layer 6 composed of _0.85 D _0.15 , D is Y
Even when an element other than the above is used, it is possible to form the rear mask region 2 in the same manner and obtain similar super-resolution reproduction characteristics. In Table 4, instead of Y, Ti, V, Cr, P
Curie temperature Tc of the reproducing layer 6 formed by using d, Cu, Al, Si, and Al _0.5 Si _0.5 alloy, and a mark length of 40 obtained in a magneto-optical disk using the reproducing layer 6.
CNR at 0 nm is shown.

[0079]

[Table 4]

In each of the magneto-optical disks, a CNR similar to that in Example 1 was obtained, and instead of Y,
Ti, V, Cr, Pd, Cu, Al, Si, Al _0.5 S
By using an element or alloy such as i _0.5 alloy, it is possible to obtain the super-resolution reproduction characteristics similar to those of the first embodiment. Further, even when these elements and alloys are used as D, Gd and Fe are used in the same manner as when Y is used.
By adjusting the composition ratio of Co, it is possible to realize the reproducing layer 6 which is in the in-plane magnetization state at room temperature and becomes the perpendicular magnetization state as the temperature rises, and it is possible to realize both the rear mask and the front mask. It is possible to realize a magneto-optical recording medium having a higher reproduction resolution by utilizing the.

[Second Embodiment] In the magneto-optical recording medium of the present embodiment, as the reproducing layer 6 in the first embodiment, GdFe or GdFeCo is made to contain a heavy rare earth metal element (HR). It is a magneto-optical recording medium using. Except for the reproducing layer 6, the description is omitted because it is the same as in the first embodiment. Note that description will be given using the same reference numerals as in the first embodiment.

In Table 5, as the reproducing layer 6, GdHRFe,
The Curie temperature of the reproducing layer 6 and the CNR at a mark length of 400 nm when GdHRFeCo is used are shown.

[0083]

[Table 5]

In all cases where Tb, Dy, Ho and Er are used as HR, the Curie temperature of the reproducing layer 6 can be set in the range of 105 ° C. to 200 ° C. by adjusting the composition ratio. In the same manner as in the first embodiment, the rear mask region 2 is formed and the super-resolution reproducing operation can be realized.

Further, also in the present embodiment, as in the first embodiment, Gd: Fe or Gd: FeC.
By adjusting the composition ratio of o to realize the reproducing layer 6 which is in-plane magnetized at room temperature and becomes perpendicularly magnetized as the temperature rises, both a rear mask and a front mask are formed, and a higher resolution is obtained. It is possible to realize the super-resolution reproduction characteristic that it has. However, when Tb or Dy is used as HL, the perpendicular magnetic anisotropy of the reproducing layer 6 becomes large, and therefore its content must be kept low.

Further, as the reproduction layer 6, GdHRFe,
Y, Ti, V, Cr, P for GdHRFeCo
Similar super-resolution reproduction characteristics can be obtained even when an element such as d, Cu, Al, or Si, or an alloy containing these elements is contained. Table 6 shows the reproduction layer 6 as GdHoF.
eD and GdHoFeCoD (D is Y, Ti,
V, Cr, Pd, Cu, Al, Si) and the Curie temperature of the reproducing layer 6 and C at a mark length of 400 nm.
NR is shown.

[0087]

[Table 6]

Also in this case, by setting the Curie temperature of the reproducing layer 6 to 105 ° C. or higher and 200 ° C. or lower, the rear mask region 2 is formed as in the first embodiment, and the super-resolution reproducing operation is performed. Can be realized. Further, as in the first embodiment, Gd: Fe, or
By adjusting the composition ratio of Gd: FeCo so as to realize the reproducing layer 6 which is in-plane magnetized at room temperature and becomes perpendicularly magnetized as the temperature rises, both a rear mask and a front mask are formed, which is higher. It is possible to realize a super-resolution reproduction characteristic having resolution. Here, the result when Ho is used as HR is shown.
In the reproducing layer 6 made of HRFeD and GdHRFeCoD, even when Tb, Dy, Er other than Ho is used as HR, the Curie temperature of the reproducing layer 6 is 10
By setting the temperature to 5 ° C. or higher and 200 ° C. or lower, the rear mask region 2 is formed and the super-resolution reproducing operation can be realized as in the first embodiment.

[Third Embodiment] In the magneto-optical recording medium of the present embodiment, as the reproducing layer 6 in the first embodiment, GdFe or GdFeCo is made to contain a light rare earth metal element (LR). It is a magneto-optical recording medium using. Except for the reproducing layer 6, the description is omitted because it is the same as in the first embodiment. Note that description will be given using the same reference numerals as in the first embodiment.

In Table 7, as the reproducing layer 6, GdLRFe,
The Curie temperature of the reproducing layer 6 and the CNR at a mark length of 400 nm when GdLRFeCo is used are shown.

[0091]

[Table 7]

When Ce, Pr, Nd, and Sm are used as LR, the Curie temperature of the reproducing layer 6 is set to 105 ° C. or higher and 200 ° C. or lower by adjusting the composition ratio, and The rear mask region 2 is formed in the same manner as in the embodiment, and the super-resolution reproducing operation can be realized.

Further, also in the present embodiment, as in the first embodiment, Gd: Fe or Gd: Fe.
By adjusting the composition ratio of Co and realizing the reproducing layer 6 which is in-plane magnetized at room temperature and becomes perpendicularly magnetized as the temperature rises, both a rear mask and a front mask are formed, and a higher resolution is obtained. It is possible to realize the super-resolution reproduction characteristic that it has.

Further, as the reproducing layer 6, GdLRFe,
For GdLRFeCo, Y, Ti, V, Cr, P
Similar super-resolution reproduction characteristics can be obtained even when an element such as d, Cu, Al, or Si, or an alloy containing these elements is contained.

Table 8 shows that the reproducing layer 6 is formed of GdNdFeD and GdNdFeCoD (D is Y, Ti, V, Cr,
The Curie temperature of the reproducing layer 6 in the case of (Pd, Cu, Al, Si) and the CNR at a mark length of 400 nm are shown.

[0096]

[Table 8]

Also in this case, the composition ratio is adjusted to
By setting the Curie temperature of the reproducing layer 6 to 105 ° C. or more and 200 ° C. or less, the rear mask region 2 is formed and the super-resolution reproducing operation can be realized as in the first embodiment.

Further, as in the first embodiment, G
Adjusting the composition ratio of d: Fe or Gd: FeCo,
By realizing the reproducing layer 6 that is in-plane magnetized at room temperature and becomes perpendicularly magnetized as the temperature rises, both a rear mask and a front mask are formed, and super-resolution reproducing characteristics with higher resolution are realized. can do.

[Fourth Embodiment] The fourth embodiment of the present invention will be described below with reference to the drawings. In this embodiment, a case where a magneto-optical disk is applied as the magneto-optical recording medium will be described.

The present magneto-optical recording medium is, as shown in FIG.
The magneto-optical disk substrate 8 has a structure in which a transparent dielectric protective layer 9, a reproducing layer 6, a recording layer 7, a transparent dielectric protective layer 12, and a reflective layer 13 are sequentially formed.

In such a magneto-optical disk, the Curie temperature recording method is used as the recording method, and the light beam 5 emitted from the semiconductor laser is narrowed down to the reproducing layer 6 and the recording layer 7, and the recording layer 7 is recorded. The recording is performed by controlling the magnetization direction of the recording layer 7 by increasing the temperature above the Curie temperature and applying an external magnetic field.

For reproduction, the same light beam is set to have weaker power than during recording, and information is reproduced by the magneto-optical effect known as the polar Kerr effect. The polar Kerr effect is a phenomenon in which the direction of rotation of the polarization plane of reflected light is reversed due to the direction of magnetization perpendicular to the light incident surface.

The substrate 8 is made of a transparent base material such as polycarbonate, is formed in a disk shape, and has a guide groove or the like on the film forming surface.

The transparent dielectric protective layer 9 is made of AlN, SiN, Al capable of preventing the reproducing layer 6 and the recording layer 7 from being oxidized.
A transparent dielectric material such as SiN or Ta2O3 can be used.

The reproducing layer 6 has a Curie temperature lower than the Curie temperature of the recording layer 7 and has a smaller perpendicular magnetic anisotropy than the recording layer 7, and in the non-laminated state with the recording layer 7, from room temperature to the Curie temperature. An alloy thin film whose main component is a rare-earth transition metal alloy that always has a coercive force smaller than that of the recording layer.

The recording layer 7 is T, which is a rare earth transition metal alloy.
It is composed of a perpendicular magnetization film having a large perpendicular magnetic anisotropy such as bFeCo or DyFeCo.

The transparent dielectric protective layer 12 is similar to the transparent dielectric protective layer 9 in that AlN, SiN, AlSiN, Ta2O3.
Transparent dielectrics such as

The reflective layer 13 is preferably a thin film having a high reflectance for the light beam used for recording / reproducing, and is made of Al, Ti, Ni, AlNi, AlTi, A.
A metal or alloy such as 1Ta can be used.

Here, the film thickness of each layer must be set so that a good interference effect is realized with respect to the incident light beam 5 and the polar Kerr rotation angle of the medium is increased. The thickness of the layer 9 is set to about 40 nm to 100 nm,
The total film thickness of the reproducing layer 6 and the recording layer 7 is 15 nm or more 4
5 nm or less and the thickness of the transparent dielectric layer 12 is 5 n
The thickness of the reflective layer 13 is set to 15 nm.
It is desirable to set to -60 nm.

Further, in the present embodiment, in order to obtain good super-resolution reproduction characteristics by forming a mask in the reproduction layer 6, the reproduction signal obtained from the reproduction layer 6 is as large as possible and the reproduction signal obtained from the recording layer 7 is as large as possible. Must be as small as possible. Therefore, the total film thickness of the reproducing layer 6 and the recording layer 7 is set to 15 nm or more and 45 nm or less and the film thickness of the recording layer 7 is 5 nm or more.
It is desirable to set the film thickness of 10 nm or more. further,
It is desirable that the thickness of the reproducing layer 6 be larger than that of the recording layer 7.

Further, in some cases, an ultraviolet curable resin, a thermosetting resin, or a lubricating layer may be formed on the protective layer 10.

Next, a specific example of the method of forming the magneto-optical disk and the recording / reproducing method of this structure will be described.

(1) Method for forming magneto-optical disk A method of forming the magnetic disk having the above structure will be described.

First, a disk-shaped polycarbonate substrate 8 having pregrooves and prepits is placed in a sputtering apparatus equipped with an Al target, a GdNdFe alloy target, a TbFeCo alloy target, and an AlTi alloy target, respectively. Then, after evacuation of the inside of the sputtering apparatus to 1 × 10 ⁻⁶ Torr,
Introducing a mixed gas of argon and nitrogen, supplying power to the Al target, and under a gas pressure of 4 × 10 ⁻³ Torr,
A transparent dielectric protective layer 9 made of AlN is formed on the substrate 8 to a thickness of 80.
nm.

Next, the inside of the sputtering apparatus is again set at 1 × 10 ^-6.
After evacuating to Torr, argon gas was introduced to supply electric power to the GdNdFe alloy target, and Gd _0.25 Nd _{0.15 0.15} on the transparent dielectric protective layer 9 under the gas pressure of 4 × 10 ⁻³ Torr. Reproducing layer 6 made of Fe _0.60
To have a film thickness of 20 nm. The reproducing layer 6 is a recording layer 7
Is a perpendicular magnetization film having a coercive force of 8 kA / m at 25 ° C. in a non-laminated state, and its Curie temperature is 160 ° C.
Met.

Then, electric power was supplied to the TbFeCo alloy target, and the recording layer 7 made of Tb _0.27 (Fe _0.88 Co _0.12 ) _0.73 was formed on the reproduction layer 6 under the gas pressure of 4 × 10 ^-3 Torr. It is formed with a film thickness of 5 nm. The recording layer 7
Had a compensation temperature of 25 ° C. and a Curie temperature of 240 ° C. in the non-laminated state with the reproduction layer 6.

Here, when the reproducing layer 6 and the recording layer 7 are compared in a non-laminated state, the perpendicular magnetic anisotropy of the reproducing layer 6 is smaller than the perpendicular magnetic anisotropy of the recording layer, and the coercive force of the reproducing layer 6 is small. Is
From 25 ° C. to its Curie temperature, the value was always smaller than the coercive force of the recording layer 7.

Next, a mixed gas of argon and nitrogen was introduced, and electric power was supplied to the Al target so that the gas pressure was 4 × 10.
^Under the condition of ⁻³ Torr, the transparent dielectric protective layer 12 made of AlN is formed with a thickness of 20 nm on the recording layer 7.

Then, the inside of the sputtering apparatus is again set at 1 × 10 ^-6.
After evacuating to Torr, argon gas was introduced to supply power to the AlTi alloy target, and the transparent dielectric protective layer 1 was formed under the gas pressure of 4 × 10 ⁻³ Torr.
A reflective layer 13 made of Al _0.90 Ti _0.10 on top of the film thickness 4
It is formed with 0 nm.

(2) Recording / reproducing characteristics The magneto-optical disk formed as described above was recorded at a wavelength of 680n.
C measured by an optical pickup using a semiconductor laser of m
The mark length dependency of NR (signal to noise ratio) is shown in FIG. 7 as a fourth embodiment. This measurement was performed in a state where the linear velocity was 5 m / s and the reproduction power was set to a power at which the maximum CNR was obtained. For comparison, the results obtained in Example 1 of the first embodiment and Comparative Example 1 are also shown in the same figure.

As can be seen from FIG. 7, in Example 4 as well as in Example 1, the CNR of the long mark length was smaller than that of Comparative Example 1, and the CNR of the shorter mark length was larger than that of Comparative Example 1. That is, the super-resolution reproduction characteristic is obtained. Further, in the fourth embodiment, the polar Kerr effect of the medium is increased by the interference effect, so that the first embodiment can be applied to any mark length.
It can be seen that a CNR that is 2 dB to 3 dB higher than that obtained is obtained.

Next, Table 9 shows the CNR at a mark length of 400 nm when the film thicknesses of the reproducing layer 6 and the recording layer 7 are changed in the present embodiment.

[0123]

[Table 9]

When the total film thickness is 60 nm and 50 nm, the maximum CNR is obtained when the reproducing layer film thickness is 40 nm or 50 nm. The CNR at this time is 42 dB, which is almost the same as the CNR of the first embodiment. This is because the total film thickness is large, so that the reproduction characteristic is not improved by the multiple interference effect using the reflected light from the reflection layer, and the super-resolution reproduction characteristic is realized as in the first embodiment. It is due to. In this case, the thickness of the reproducing layer becomes thinner, and the rear mask effect in the reproducing layer becomes weaker, resulting in CNR.
Deteriorates.

Next, the total film thickness is 45 nm and 35 n.
When m, 30 nm, 25 nm, 20 nm, and 15 nm, the maximum CNRs are 43.0 dB and 43.5, respectively.
dB, 44.5 dB, 45.0 dB, 44.5 dB, 4
It is 2.5 dB, and it can be seen that in any case, a large CNR is obtained as compared with the CNR (42 dB) when the multiple interference effect is not obtained. However, when the total film thickness becomes as thin as 10 nm, the total magnetic layer becomes too thin, so that a good interference effect cannot be realized and the reproducing layer itself becomes thin, and a good mask effect cannot be obtained, which is extremely small. Only CNR can be obtained.

From the above results, in the present embodiment, by setting the total film thickness to 15 nm or more and 45 nm or less, it is possible to improve the reproduction characteristic by the multiple interference effect using the reflected light from the reflective layer. Recognize.

Next, when the thickness of the reproducing layer 6 was set to 5 nm, the CNR of Comparative Example 1 was obtained at any total thickness.
Only CNR smaller than (29 dB) is obtained.
This is because the thin film thickness of the reproducing layer 6 becomes too thin, and the rear mask effect in the reproducing layer 6 becomes weak, so that the improvement of the reproducing resolution due to the super-resolution reproducing cannot be realized. The thickness of the layer 6 is 10n
It can be seen that a film thickness of m or more is necessary.

Next, when the film thickness of the recording layer is 3 nm, an extremely low CNR is obtained in any film thickness constitution. This is because the recording layer 7 becomes too thin, It is probable that this was because normal recording was not performed. From this, it is understood that the film thickness of the recording layer 7 needs to be 5 nm or more.

Further, as compared with the CNR (42 dB) in the case where the above multiple interference effect is not obtained, the film thickness composition when a large CNR is obtained is examined (total film thickness, reproduction layer film thickness, recording layer (Layer thickness) as (45 nm, 30 n
m, 15 nm) (45 nm, 40 nm, 5 nm) (3
5, 25, 10) (35 nm, 30 nm, 5 nm) (2
5nm, 15nm, 10nm) (25nm, 20nm,
5nm) (20nm, 10nm, 10nm) (20n
m, 15 nm, 5 nm) (15 nm, 10 nm, 5n
m), and utilizing the multiple interference effect,
In order to obtain a higher CNR, it is desirable that (reproduction layer thickness ≧ recording layer thickness).

In the present embodiment, the result when Gd _0.25 Nd _0.15 Fe _0.60 is used as the reproducing layer 6 is shown. However, as the reproducing layer 6, the first embodiment and the second embodiment are used. Form, G described in the third embodiment
dFeD, GdFeCoD, GdHRFe, GdHRF
eCo, GdHRFeD, GdHRFeCoD, GdL
RFe, GdLRFeCo, GdLRFeD, GdLR
It is possible to use materials such as FeCoD.

Further, also in this embodiment, as in the embodiment, the composition ratio of Gd: Fe or Gd: FeCo is adjusted so that the in-plane magnetization state is obtained at room temperature, and the perpendicular magnetization state is obtained as the temperature rises. By realizing the reproducing layer 6 such that, both the rear mask and the front mask can be formed, and the super-resolution reproducing characteristic having higher resolution can be realized.

[Fifth Embodiment] The fifth embodiment of the present invention will be described below with reference to the drawings. In this embodiment, a case where a magneto-optical disk is applied as the magneto-optical recording medium will be described.

The present magneto-optical recording medium is, as shown in FIG.
A transparent dielectric protective layer 9, a reproducing layer 6, a recording layer 7, a non-magnetic layer 14, a recording auxiliary layer 15, and a protective layer 10 are sequentially formed on a magneto-optical disk substrate 8.

In such a magneto-optical disk, the Curie temperature recording method is used as the recording method, and the light beam 5 emitted from the semiconductor laser is focused on the reproducing layer 6 and the recording layer 7, and the recording layer 7 is recorded. The recording is performed by controlling the magnetization direction of the recording layer 7 by increasing the temperature above the Curie temperature and applying an external magnetic field.
In reproduction, the same light beam is set to have a weaker power than during recording, and information is reproduced by a magneto-optical effect known as a polar Kerr effect. The polar Kerr effect is a phenomenon in which the direction of rotation of the polarization plane of reflected light is reversed due to the direction of magnetization perpendicular to the light incident surface.

The substrate 8 is made of a transparent base material such as polycarbonate, is formed in a disk shape, and has a guide groove or the like on the film forming surface.

The transparent dielectric protective layer 9 is made of AlN, SiN,
It is desirable to use a transparent dielectric such as AlSiN or Ta ₂ O ₃ , and its film thickness is set so that a good interference effect is realized with respect to the incident light beam 5 and the polar Kerr rotation angle of the medium is increased. When the wavelength of the light beam 5 is 1, and the refractive index of the transparent dielectric protective layer 9 is n, the film thickness of the transparent dielectric protective layer 9 is set to about (l / (4n)). It For example, when the wavelength of the light beam 5 is 680 nm, the film thickness of the transparent dielectric protective layer 9 may be set to about 40 nm to 100 nm.

The reproducing layer 6 has a Curie temperature lower than the Curie temperature of the recording layer 7 and has a smaller perpendicular magnetic anisotropy than the recording layer 7, and in the non-laminated state with the recording layer 7, from room temperature to the Curie temperature. An alloy thin film whose main component is a rare earth-transition metal alloy having a coercive force smaller than the coercive force of the recording layer, and the film thickness is set in the range of 20 to 80 nm. When the thickness of the reproducing layer 6 is thinner than 20 nm, a good rear mask effect cannot be obtained, and when the thickness of the reproducing layer 6 is thicker than 80 nm, the recording sensitivity is significantly deteriorated due to the increase of the thickness.

The recording layer 7 is composed of a perpendicularly magnetized film made of a rare earth transition metal alloy, and its film thickness is set in the range of 5 nm to 80 nm. When the film thickness of the recording layer 7 is thinner than 5 nm, it becomes difficult to form the recording layer 7 with good reproducibility. When the film thickness of the recording layer 7 is thicker than 80 nm, the recording sensitivity is significantly deteriorated due to the increase of the film thickness. come.

The nonmagnetic layer 14 includes the recording layer 7 and the recording auxiliary layer 1.
It is provided so that only a magnetostatic coupling force works between it and 5, and is a transparent dielectric such as AlN, SiN, AlSiN, Ta ₂ O ₃ or a non-magnetic material such as a metal such as Al, Ti or Ta. Since it is a metal alloy and an appropriate magnetostatic coupling force is exerted between the recording layer 7 and the recording auxiliary layer 15, its film thickness is 1
It is set from 40 nm to 40 nm.

The recording auxiliary layer 15 has an in-plane magnetized state at room temperature, a perpendicular magnetized state as the temperature rises, and a magnetic characteristic set to be a perpendicular magnetized state at least at the Curie temperature of the recording layer 7, and at the time of recording. With respect to the recording magnetic field applied from the outside, the magnetization of the temperature-increased portion of the recording auxiliary layer 15 is oriented in the direction of the recording magnetic field, so that the leakage magnetic field generated from the recording auxiliary layer 15 is generated.
On the other hand, the recording auxiliary layer 15 works in the same direction as the recording magnetic field and is used for reducing the recording magnetic field. In order to generate a sufficiently large leakage magnetic field, the film thickness of the recording auxiliary layer 15 is
It needs to be set to 20 nm or more. Further, if the film thickness of the recording auxiliary layer is too thick, the recording sensitivity will be lowered. Therefore, it is desirable to set the film thickness to 80 nm or less.

The protective layer 10 is made of AlN, SiN, AlSi.
Transparent dielectric such as N, Ta ₂ O ₃ or Al, Ti, T
The reproducing layer 6 is made of a non-magnetic metal alloy made of a metal such as a.
It is formed for the purpose of preventing the rare earth-transition metal alloy used for the recording layer 7 and the recording layer 7 from being oxidized, and the film thickness is 5 nm to 6 nm.
It is set in the range of 0 nm.

Further, in some cases, an ultraviolet curable resin, a thermosetting resin, or a lubricating layer may be formed on the protective layer 10.

Specific examples of the method of forming the magneto-optical disk and the recording / reproducing method of this structure will be described below.

(1) Method for forming magneto-optical disk A method of forming the magnetic disk having the above structure will be described.

First, an Al target, a GdFeY alloy target, a TbFeCo alloy target, and a GdFeCo target.
In the sputtering equipment equipped with alloy target,
A polycarbonate substrate 8 having a pre-groove and pre-pit and formed in a disk shape is arranged. And
Similar to the first embodiment, a transparent dielectric protective layer 9 made of AlN is formed on the substrate 8 with a film thickness of 80 nm, and (Gd _0.25 Fe _0.75 ) _0.92 Y is formed on the transparent dielectric protective layer 9.
_A reproducing layer 6 made of _0.08 is formed to a thickness of 40 nm, and a recording layer 7 made of Tb _0.25 (Fe _0.88 Co _0.12 ) _0.75 is formed to a thickness of 40 nm on the reproducing layer 6.

Next, a mixed gas of argon and nitrogen was introduced, and electric power was supplied to the Al target so that the gas pressure was 4 × 10.
^The nonmagnetic layer 14 made of AlN is formed on the recording layer 7 to have a film thickness of 5 nm under the condition of ⁻³ Torr.

Next, the inside of the sputtering apparatus is again set at 1 × 10 ^-6.
After evacuating to Torr, argon gas was introduced to supply electric power to the GdFeCo alloy target, and Gd _0.35 (Fe _0.70 Co was formed on the nonmagnetic layer 14 under the gas pressure of 4 × 10 ⁻³ Torr. _A recording auxiliary layer 15 of _0.30 ) _0.65 is formed with a film thickness of 40 nm. The recording auxiliary layer 1
No. 5 had an in-plane magnetization state at 25 ° C., a completely perpendicular magnetization state at 240 ° C., and its Curie temperature was 330 ° C.

Next, a mixed gas of argon and nitrogen was introduced, and electric power was supplied to the Al target so that the gas pressure was 4 × 10.
^Under the condition of ^-3 Torr, the protective layer 10 made of AlN is formed on the recording layer 7 to have a film thickness of 20 nm.

(2) Recording / reproducing characteristics Mark length of CNR (signal to noise ratio) of the magneto-optical disk (described as Example 5) formed as described above, measured by an optical pickup using a semiconductor laser having a wavelength of 680 nm. As a result of examining the dependency, C which is almost the same as that of the first embodiment shown in FIG.
The dependency of NR on the mark length was confirmed. However, in this measurement, the linear velocity was set to 5 m / s, and the reproduction power was adjusted to obtain the maximum CNR.

The magneto-optical recording medium in this embodiment is
By the magnetostatic coupling of the recording layer 7 and the recording auxiliary layer 15,
The feature is that the recording magnetic field can be reduced.

FIG. 9 shows optical modulation recording in the magneto-optical recording medium of the structure without the recording auxiliary layer 15 manufactured as a trial in Example 1 and in the magneto-optical recording medium of the structure having the recording auxiliary layer 15 manufactured as a prototype in Example 5. It shows the recording magnetic field dependence of CNR in the case of a mark length of 400 nm, which was investigated by the method. Here, the recording / reproducing power is optimized and measured for each of the first and fifth embodiments. According to FIG. 9, in the magneto-optical recording medium of Example 1, complete recording at a recording magnetic field of ± 20 kA / m
While erasing is realized, in the magneto-optical recording medium of Example 5, complete recording / recording is performed with a recording magnetic field of ± 8 kA / m.
It can be seen that erasing has been realized.

As described above, in the present embodiment, it is possible to achieve both the super-resolution reproducing characteristic by the mask effect of the reproducing layer 6 and the low magnetic field recording by the recording auxiliary layer 15.

In the fifth embodiment, as the reproducing layer 6,
Although the results of using (Gd _0.25 Fe _0.75 ) _0.92 Y _0.08 are shown, as the reproducing layer 6, GdFeD, GdFeCoD, and Gd described in the first to third embodiments are used.
HRFe, GdHRFeCo, GdHRFeD, GdH
RFeCoD, GdLRFe, GdLRFeCo, Gd
Materials such as LRFeD and GdLRFeCoD can be used.

Further, also in the fifth embodiment, the first
Similar to the embodiment described above, Gd: Fe or Gd: F
Adjusting the composition ratio of eCo, it is in-plane magnetized state at room temperature,
By realizing the reproducing layer 6 which becomes the perpendicular magnetization state with the temperature rise, both the rear mask and the front mask can be formed, and the super-resolution reproducing characteristic having higher resolution can be realized.

[Sixth Embodiment] The following will describe an embodiment of the present invention with reference to the drawings. In the present embodiment, a case where it is applied to a magneto-optical disk as a magneto-optical recording medium will be described.

The magneto-optical recording medium of the present invention, as shown in FIG. 10, has a transparent dielectric protective layer 9, a reproducing layer 6, a recording layer 7, a transparent dielectric protective layer 12, a recording auxiliary on a magneto-optical disk substrate 8. It has a structure in which the layer 15 and the protective layer 10 are sequentially formed.

In such a magneto-optical disk, the Curie temperature recording method is used as the recording method, and the light beam 5 emitted from the semiconductor laser is focused on the reproducing layer 6 and the recording layer 7, and the recording layer 7 is recorded. The recording is performed by controlling the magnetization direction of the recording layer 7 by increasing the temperature above the Curie temperature and applying an external magnetic field.
In reproduction, the same light beam is set to have a weaker power than during recording, and information is reproduced by a magneto-optical effect known as a polar Kerr effect. The polar Kerr effect is a phenomenon in which the direction of rotation of the polarization plane of reflected light is reversed due to the direction of magnetization perpendicular to the light incident surface.

The substrate 8 is made of a transparent base material such as polycarbonate, is formed in a disk shape, and has a guide groove or the like on the film forming surface.

The transparent dielectric protective layer 9 is made of AlN, SiN, Al capable of preventing the reproducing layer 6 and the recording layer 7 from being oxidized.
A transparent dielectric material such as SiN or Ta ₂ O ₃ can be used.

The reproducing layer 6 has a Curie temperature lower than the Curie temperature of the recording layer 7 and has a smaller perpendicular magnetic anisotropy than the recording layer 7, and in the non-laminated state with the recording layer 7, from room temperature to the Curie temperature. An alloy thin film whose main component is a rare-earth transition metal alloy that always has a coercive force smaller than that of the recording layer.

The recording layer 7 is made of T which is a rare earth transition metal alloy.
It is composed of a perpendicular magnetization film having a large perpendicular magnetic anisotropy such as bFeCo or DyFeCo.

As the transparent dielectric protective layer 12, a transparent dielectric such as AlN, SiN, AlSiN, Ta ₂ O ₃ can be used as in the transparent dielectric protective layer 9.

The recording auxiliary layer 15 has an in-plane magnetized state at room temperature, a perpendicular magnetized state as the temperature rises, and a magnetic characteristic set to be a perpendicular magnetized state at least at the Curie temperature of the recording layer 7, and at the time of recording. With respect to the recording magnetic field applied from the outside, the magnetization of the temperature-increased portion of the recording auxiliary layer 15 is oriented in the direction of the recording magnetic field, so that the leakage magnetic field generated from the recording auxiliary layer 15 is generated.
On the other hand, the recording auxiliary layer 15 works in the same direction as the recording magnetic field and is used for reducing the recording magnetic field. In order to generate a sufficiently large leakage magnetic field, the film thickness of the recording auxiliary layer 15 is
It needs to be set to 20 nm or more. Further, if the film thickness of the recording auxiliary layer is too thick, the recording sensitivity will be lowered. Therefore, it is desirable to set the film thickness to 80 nm or less.

The protective layer 10 is made of AlN, SiN, AlSi.
Transparent dielectric such as N, Ta ₂ O ₃ or Al, Ti, T
The reproducing layer 6 is made of a non-magnetic metal alloy made of a metal such as a.
It is formed for the purpose of preventing the rare earth-transition metal alloy used for the recording layer 7 and the recording layer 7 from being oxidized, and the film thickness is 5 nm to 6 nm.
It is set in the range of 0 nm.

Further, in some cases, an ultraviolet curable resin, a thermosetting resin, or a lubricating layer may be formed on the protective layer 10.

Here, the film thicknesses of the transparent dielectric protective layer 9, the reproducing layer 6, the recording layer 7 and the transparent dielectric layer 1 realize a good interference effect with respect to the incident light beam 5, and the thickness of the medium is reduced. The recording auxiliary layer 1 needs to be set to increase the polar car rotation angle.
5 can be considered as the reflective layer 13 of the fourth embodiment, and the film thickness of each layer is the same as that of the fourth embodiment, and the film thickness of the transparent dielectric protective layer 9 is 40 nm to 100 nm.
It is desirable that the total film thickness of the reproducing layer 6 and the recording layer 7 is set to 15 nm or more and 45 nm or less, and the film thickness of the transparent dielectric layer 12 is set to 5 nm to 30 nm. Further, in the present embodiment as well, as in the fourth embodiment, in order to obtain good super-resolution reproduction characteristics by forming a mask in the reproduction layer 6, the reproduction signal obtained from the reproduction layer 6 is as large as possible. It is necessary that the reproduction signal obtained from 7 is as small as possible. Therefore, the total film thickness of the reproducing layer 6 and the recording layer 7 is 15 nm or more and 45 n or more.
m or less and the thickness of the recording layer 7 is set to 5 nm.
As described above, it is desirable that the thickness of the reproducing layer 6 be 10 nm or more. Further, it is desirable that the thickness of the reproducing layer 6 be larger than that of the recording layer 7.

Next, a specific example of the method of forming the magneto-optical disk and the recording / reproducing method of this structure will be described.

(1) Method of Forming Magneto-Optical Disk A method of forming the magneto-optical disk having the above structure will be described.

First, an Al target, a GdNdFe alloy target, a TbFeCo alloy target, and a GdFeC target.
Inside the sputtering equipment equipped with each o alloy target,
A polycarbonate substrate 8 having a pre-groove and pre-pit and formed in a disk shape is arranged. And
In the same manner as in Example 4, the transparent dielectric protective layer 9 made of AlN was formed on the substrate 8 to a thickness of 80 nm, and the reproducing layer 6 made of Gd _0.25 Nd _0.15 Fe _0.60 was formed on the transparent dielectric protective layer 9. Is formed to a film thickness of 20 nm, and T is formed on the reproduction layer 6.
A recording layer 7 made of b _0.27 (Fe _0.88 Co _0.12 ) _0.73 is formed with a thickness of 5 nm.

Next, a mixed gas of argon and nitrogen was introduced, and electric power was supplied to the Al target to produce a gas pressure of 4 × 10.
^The nonmagnetic layer 14 made of AlN is formed on the recording layer 7 to have a film thickness of 5 nm under the condition of ⁻³ Torr.

Next, the inside of the sputtering apparatus is again set at 1 × 10 ^-6.
After evacuating to Torr, argon gas was introduced to supply electric power to the GdFeCo alloy target, and Gd _0.35 (Fe _0.70 Co was formed on the nonmagnetic layer 14 under the gas pressure of 4 × 10 ⁻³ Torr. _A recording auxiliary layer 15 of _0.30 ) _0.65 is formed with a film thickness of 40 nm. The recording auxiliary layer 1
No. 5 had an in-plane magnetization state at 25 ° C., a completely perpendicular magnetization state at 240 ° C., and its Curie temperature was 330 ° C.

Next, a mixed gas of argon and nitrogen was introduced, and electric power was supplied to the Al target so that the gas pressure was 4 × 10.
^Under the condition of ^-3 Torr, the protective layer 10 made of AlN is formed on the recording layer 7 to have a film thickness of 20 nm.

(2) Recording / reproducing characteristics Mark length of CNR (signal to noise ratio) of the magneto-optical disk (described as Example 6) formed as described above, measured by an optical pickup using a semiconductor laser having a wavelength of 680 nm. As a result of examining the dependency, C which is almost the same as that of the fourth embodiment shown in FIG.
The dependency of NR on the mark length was confirmed. However, in this measurement, the linear velocity was set to 5 m / s, and the reproduction power was adjusted to obtain the maximum CNR.

The magneto-optical recording medium in this embodiment is
By the magnetostatic coupling of the recording layer 7 and the recording auxiliary layer 15,
The feature is that the recording magnetic field can be reduced.

FIG. 11 shows a magneto-optical recording medium having the recording auxiliary layer 15 of Example 4 without the recording auxiliary layer 15 and a reflective layer 13 and a magneto-optical recording medium having the recording auxiliary layer 15 of Example 6. , Investigated by optical modulation recording method,
It shows the recording magnetic field dependence of CNR in the case of a mark length of 400 nm. Here, the recording / reproducing power is optimized and measured for each of Example 4 and Example 6. According to FIG. 11, in the magneto-optical recording medium of Example 4, complete recording / erasing was realized with a recording magnetic field of ± 15 kA / m, whereas in the magneto-optical recording medium of Example 5, ± 6 kA. It can be seen that complete recording / erasing is achieved with a recording magnetic field of / m.

As described above, in the present embodiment, it is possible to achieve both the super-resolution reproduction characteristic by the mask effect of the reproduction layer 6 and the low magnetic field recording by the recording auxiliary layer 15.

In the present embodiment, the results obtained when Gd _0.25 Nd _0.15 Fe _0.60 is used as the reproducing layer 6 are shown, but as the reproducing layer 6, Example 1, Example 2, and Example are shown. GdFeD and GdFeCo described in 3.
D, GdHRFe, GdHRFeCo, GdHRFe
D, GdHRFeCoD, GdLRFe, GdLRFe
Materials such as Co, GdLRFeD, and GdLRFeCoD can be used.

Furthermore, also in the present embodiment, as in the fourth embodiment, Gd: Fe or Gd: FeCo.
A rear mask and a front mask are both formed by adjusting the composition ratio of (1) to realize a reproducing layer 6 that is in-plane magnetized at room temperature and becomes perpendicularly magnetized as the temperature rises, and has higher resolution. Super-resolution reproduction characteristics can be realized.

[0179]

As described above, according to the magneto-optical recording medium of the present invention, GdFe or Gd having a small perpendicular magnetic anisotropy.
It is possible to effectively lower the Curie temperature of the perpendicular magnetization film made of FeCo, and obtain good recording / reproducing characteristics as a super-resolution magneto-optical recording medium.

Further, like the magneto-optical recording medium of the present invention ,
If the reproducing layer is brought into an in-plane magnetization state at room temperature, in addition to the mask being formed in the portion above the Curie temperature, the in-plane magnetization mask is formed in the temperature region below the critical temperature, Super-resolution reproduction with higher resolution becomes possible.

According to the magneto-optical recording medium of the present invention ,
Due to the optical interference effect, the super-resolution reproducing characteristic can be improved, and the protective layer shields the reproducing layer and the recording layer from the outside air to protect them from deterioration such as oxidation.

Further, like the magneto-optical recording medium of the present invention ,
By adjusting the film thickness of the reproducing layer and the recording layer, the Kerr rotation angle can be increased by utilizing the multiple interference effect, and it becomes possible to improve the super-resolution reproducing characteristic, and the reproducing resolution is high and the reproducing It becomes possible to realize super-resolution reproduction with high signal strength.

According to the magneto-optical recording medium of the present invention ,
Due to the optical interference effect of the transparent dielectric protective layer, it is possible to improve the super-resolution reproducing characteristic, and to shield the reproducing layer and the recording layer from the outside air and protect them from deterioration such as oxidation. Become.

Further, according to the magneto-optical recording medium of the present invention ,
It is possible to obtain the super-resolution reproduction characteristic of the present invention and further reduce the recording magnetic field.

According to the magneto-optical recording medium of the present invention ,
Super-resolution reproduction characteristics can be improved by the optical interference effect of the transparent dielectric protective layer, and the protective layer shields the reproducing layer and the recording layer from the outside air and protects them from deterioration such as oxidation. Is possible. Further, by forming the non-magnetic layer between the recording layer and the recording auxiliary layer, it becomes possible to realize a stable magnetostatic coupling state between the recording layer and the recording auxiliary layer, and to stably generate the recording magnetic field. It can be reduced. If the non-magnetic layer is used as the transparent dielectric layer and the recording auxiliary layer is also used as the reflective layer, it is possible to improve the super-resolution reproduction characteristics by the optical interference effect without providing a special reflective layer. Become. In addition, the magnetic recording medium of the present invention
According to the raw method, super-resolution reproduction with high resolution can be realized.

[Brief description of drawings]

FIG. 1 is a schematic plan view illustrating a reproducing principle of a magneto-optical disk of the present invention.

FIG. 2 is a schematic cross-sectional view for explaining the reproducing principle of the magneto-optical disk of the present invention.

FIG. 3 is a cross-sectional view showing the configuration of the magneto-optical disk according to the first embodiment.

FIG. 4 is a diagram showing the mark length dependence of CNR of the magneto-optical disk of the first embodiment.

FIG. 5 is a schematic sectional view for explaining the reproducing principle of the magneto-optical disk of the present invention.

FIG. 6 is a sectional view showing the structure of a magneto-optical disk according to a fourth embodiment.

FIG. 7 is a diagram showing the mark length dependence of CNR of the magneto-optical disk of the fourth embodiment.

FIG. 8 is a sectional view showing the structure of a magneto-optical disk according to a fifth embodiment.

FIG. 9 is a diagram showing the recording magnetic field dependence of CNR of the magneto-optical disk of the fifth embodiment.

FIG. 10 is a sectional view showing the structure of a magneto-optical disk according to a sixth embodiment.

FIG. 11 is a CNR of a magneto-optical disk according to a sixth embodiment.
FIG. 6 is a diagram showing the recording magnetic field dependence of

[Explanation of symbols]

1 light beam spot 2 Rear mask area 6 playback layers 7 Recording layer 9 Transparent dielectric layer 10 Protective layer 12 Transparent dielectric layer 13 Reflective layer 14 Non-magnetic layer 15 Recording auxiliary layer

   ─────────────────────────────────────────────────── ─── Continued front page       (56) Reference JP-A-5-342670 (JP, A)                 JP-A-6-309729 (JP, A)                 JP-A-8-221824 (JP, A)                 JP-A-8-36793 (JP, A)                 JP-A-8-221825 (JP, A)                 JP-A-5-205333 (JP, A)

Claims (11)

(57) [Claims] 1. A magneto-optical recording medium having a two-layer magnetic layer in which a recording layer made of a perpendicularly magnetized film and a reproducing layer having a Curie temperature lower than the Curie temperature of the recording layer are exchange-coupled to each other. Is GdFeD or GdFeCoD
(D is an element selected from Y, Ti, V, Cr, Pd, Cu, Al and Si, or an alloy composed of two or more of these elements). 2. A reproducing layer in a magneto-optical recording medium having a two-layer magnetic layer in which a recording layer made of a perpendicularly magnetized film and a reproducing layer having a Curie temperature lower than the Curie temperature of the recording layer are exchange-coupled. Is GdHRFe or G
dHRFeCo or GdHRFeD or G
dHRFeCoD (HR is an element selected from Tb, Dy, Ho and Er, or an alloy of two or more of these elements, D is Y, Ti, V, Cr, Pd, Cu,
Elements selected from Al and Si, or two of them
A magneto-optical recording medium characterized by comprising an alloy consisting of more than one kind of element). 3. A magneto-optical recording medium having a two-layer magnetic layer in which a recording layer made of a perpendicularly magnetized film and a reproducing layer having a Curie temperature lower than the Curie temperature of the recording layer are exchange-coupled to each other. Is GdLRFe or G
dLRFeCo or GdLRFeD or G
dLRFeCoD (LR is an element selected from Ce, Pr, Nd, and Sm, or an alloy of two or more of these elements, D is Y, Ti, V, Cr, Pd, Cu,
Elements selected from Al and Si, or two of them
A magneto-optical recording medium characterized by comprising an alloy consisting of more than one kind of element). 4. The magneto-optical recording medium according to claim 1 , further comprising: a magneto-optical disk substrate,
A magneto-optical recording medium comprising a transparent dielectric protective layer, a reproducing layer, a recording layer, and a protective layer, which are sequentially formed. 5. The magneto-optical recording medium according to claim 1 , further comprising a reflective layer on the side opposite to the reproducing layer with respect to the recording layer, A magneto-optical recording medium, wherein the sum of the film thicknesses of the recording layers is 15 nm or more and 45 nm or less. 6. The magneto-optical recording medium according to claim 5 , wherein the recording layer has a film thickness of 5 nm or more and the reproducing layer has a film thickness of 10 nm or more. Medium. 7. The magneto-optical recording medium according to claim 5 or 6 , wherein a transparent dielectric protective layer, the reproducing layer, the recording layer, a transparent dielectric protective layer, and the reflection are provided on a magneto-optical disk substrate. A magneto-optical recording medium comprising layers formed in sequence. 8. A magneto-optical recording medium according to claim 1 , which is in-plane magnetized at room temperature and perpendicularly magnetized at least at the Curie temperature of the recording layer. A magneto-optical recording medium, wherein the auxiliary layer is magnetostatically coupled to the recording layer. 9. The magneto-optical recording medium according to claim 8 , wherein the transparent dielectric protective layer, the reproducing layer, the recording layer, the non-magnetic layer, the recording auxiliary layer and the protective layer are provided on the magneto-optical disk substrate. A magneto-optical recording medium, which is formed sequentially. 10. A recording layer comprising a perpendicular magnetization film, and a recording layer.
Layer with a Curie temperature lower than that of
Magneto-optical recording having a two-layer magnetic layer exchange-coupled with
A method of reproducing a medium, wherein the reproducing layer is at room temperature.
Is an in-plane magnetization state, and at temperatures above the critical temperature
A magnetic film that is perpendicularly magnetized, and emits a laser beam for reproduction as the recording medium moves.
To the rear of the light beam spot
A rear mask region where the magnetization of the
A method for reproducing a magneto-optical recording medium, characterized by: 11. A magneto-optical recording medium in the rear mask area.
The body temperature is higher than the Curie temperature of the reproducing layer and the recording layer
Features that you play by the temperature rise to the Curie temperature equal to or lower than the
A method of reproducing the magneto-optical recording medium according to claim 10,
Law.