JPH11176034A - Magneto-optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magneto-optical recording medium in which the information in a memory film is surely masked by both high and low temperature regions in a beam spot even though the external magnetic field applied during a reproducing is small and a high density information in the memory film only can be accurately reproduced by a small medium temperature region. SOLUTION: On the substrate 21 of the magneto-optical recording medium 10, a reproducing film 11, which is made of a vertically magnetized film, a reproducing intermediate film 12, which is made of an intrasurface magnetized film, a reproducing auxiliary film 13, which is made of an intrasurface magnetized film, and a memory film 14, which is made of a vertically magnetized film, are successively formed. Note that the Curie temperature of the film 12 is lower than the Curie temperatures of both the films 11 and 14. The Curie temperature of the film 13 is lower than either one of the Curie temperatures of the films 11 or 14 and the temperature, in which the intrasurface magnetization state is changed to the vertically magnetization state, is high than the temperature, in which the intrasurface magnetization state of the film 12 is changed to a vertically magnetized state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magneto-optical recording medium capable of reproducing information by magnetic super-resolution.

[0002]

2. Description of the Related Art Conventionally, in a magneto-optical disk (magneto-optical recording medium), a technology for recording information at a high density and a technique for accurately reproducing the information recorded at a high density have been proposed in order to meet a demand for a large capacity. Both techniques are needed.

[0003] Among them, a technique for recording information at high density includes a pen tip recording method. This pen tip recording method utilizes a temperature distribution generated in a magneto-optical disk by irradiation of recording light,
A recording mark smaller than a beam spot of recording light is formed in a region where the temperature of the magneto-optical disk is higher than a predetermined temperature. In addition, technologies for accurately reproducing high-density information include magnetic super-resolution technology (Magnetic-ly induced
Super Resolution). This magnetic super-resolution technology,
The recording mark is reproduced in an area smaller than the beam spot of the reproducing light by utilizing the temperature distribution generated in the magneto-optical disk by the irradiation of the reproducing light.

In recent years, various types of magnetic super-resolution techniques have been proposed, one of which is a double mask method (hereinafter referred to as "D-RAD"). The D-RAD performs reproduction in a small area where the temperature of the magneto-optical disk falls within a predetermined range by irradiation of the reproduction light. These two technologies (brush writing method, DR
The magneto-optical disk 100 incorporating AD) has a structure shown in FIG. That is, the magneto-optical disk 100 includes a protective film 122, a reproducing film 111, and a reproducing intermediate film 1 on a substrate 121 from above to below in FIG.
12, a memory film 113 and a protective film 123 are sequentially formed.

[0005] Among them, the memory film 113 is a perpendicular magnetization film on which information is recorded by using the pen tip recording method. When recording light is applied to record information, the magneto-optical disk 1
00 has a temperature distribution, and its temperature becomes higher than a predetermined temperature Tk in a small area within the beam spot of the recording light.

At this time, the memory film 113 in a small area
Since the coercive force is reduced, the magnetization direction can be reversed under the influence of an external magnetic field. As a result, one recording mark 113A smaller than the beam spot of the recording light is formed on the memory film 113. Further, such small recording marks 113A can be successively formed on the memory film 113 by irradiating recording light intermittently according to information.

In addition, information (a plurality of recording marks 113A,
113A,...) Can be reproduced one by one using D-RAD by the reproduction film 111 and the reproduction intermediate film 112. Here, the reproducing film 111 is a perpendicular magnetization film, and the reproducing intermediate film 1
Reference numeral 12 denotes an in-plane magnetization film. When the reproduction light 141 is irradiated in reproducing the information, a temperature distribution is generated in the magneto-optical disk 100, and the beam spot 14 of the reproduction light 141 is generated.
The inside of 1A can be considered by dividing into three regions at a certain temperature (FIGS. 10 and 11).

[0008] The three areas are in the disk moving direction 10
0A, in order from the front (left side in FIG. 10), a semicircular high-temperature region 141F whose temperature is higher than a predetermined temperature Ts1,
An intermediate temperature region 141E lower than the predetermined temperature Ts1 and higher than the predetermined temperature Ts2, and a low temperature region 141D lower than the predetermined temperature Ts2. Thus, the disk moving direction 10
The higher the temperature is in the region located in front of 0A, the more the temperature is higher than the region located in the rear (to the right in FIG. 10) when the magneto-optical disk 100 moves in the disk moving direction 100A (in FIG. 10). , Left) is irradiated with the reproduction light 141 for a long time.

[0009] Of the beam spot 141A in which three regions having different temperatures are generated, the recording mark 1 of the memory film 113 is formed between the high temperature region 141F and the low temperature region 141D.
Are masked without being transferred to the reproduction film 111. Here, in the conventional D-RAD, a reproducing magnetic field Hr of a constant magnitude is continuously applied to the beam spot 141A, and the high-temperature area 141F and the low-temperature area 14F are applied.
By maintaining the magnetization of the 1D reproducing film 111 in a constant perpendicular magnetization state, the high-temperature region 141F and the low-temperature region 141D
To ensure that the recording marks 113A, 11
3A,... Were masked.

In the high-temperature region 141F of these two maskable regions, the magnetization of the reproducing intermediate film 112 has disappeared. Can be kept in condition. However, in the low temperature region 141D, the reproduced intermediate film 11
The magnetization of No. 2 is maintained in an in-plane magnetization state if there is no adjacent magnetic body, but when a magnetic film is formed adjacently, it is affected by the exchange coupling force from the magnetic film, The in-plane magnetization state becomes unstable.

Therefore, in the low temperature region 141D,
The magnetization of the reproducing intermediate film 112 is
Under the influence of the exchange coupling force from (the magnetization is in a perpendicular magnetization state), the orientation tends to be the same in accordance with the magnetization of the memory film 14. If the magnetization of the reproducing intermediate film 112 is oriented in the same direction as the magnetization of the memory film 114, it is directly transferred to the reproducing film 111 by the exchange coupling force, and the magnetization of the reproducing film 111 has a constant perpendicular magnetization. The state is not maintained and the mask becomes insufficient.

For this reason, in the conventional D-RAD, the magnitude of the reproducing magnetic field Hr is set to 500 to keep the magnetization of the reproducing film 111 in a constant perpendicular magnetization state in the low temperature region 141D.
(Oe) to about 600 (Oe). On the other hand, in the middle temperature region 141E, the magnetization of the reproducing intermediate film 112 changes from the in-plane magnetization state to the perpendicular magnetization state. For this reason,
In the medium temperature region 141E, one of the recording marks 113A, 113A,... Formed on the memory film 113 is changed from the reproducing intermediate film 112 (transfer mark 112A) to the reproducing film 111.
(Transfer mark 111A).

Therefore, by detecting the component of the reproduction light 141 reflected by the beam spot 141A, only one transfer mark 111A formed on the reproduction film 111 in the small middle temperature region 141E can be accurately detected (for example, crosstalk occurs). Can be played). Thus, according to the conventional D-RAD, a large reproducing magnetic field Hr
Is applied, the mask is surely formed not only in the high-temperature region 141F but also in the low-temperature region 141D, and the recording marks 113A, 113A,. Can be played.

[0014]

Here, the conventional D-R
In AD, a large reproducing magnetic field Hr (500 (Oe) to 6
In order to apply (00 (Oe)) to the magneto-optical disk 100, it is necessary to incorporate a magnet having a large outer shape or a magnetic coil having a large number of turns and a large power supply in the recording / reproducing apparatus. .

However, the recent recording / reproducing apparatus must be miniaturized, and the incorporation of such a large magnetic field source hinders miniaturization. Further, a recording / reproducing apparatus having a built-in large magnetic field generating source is expensive because of its large size. An object of the present invention is to mask information recorded on a memory film in both a low-temperature region and a high-temperature region within a beam spot of a reproduction light. It is another object of the present invention to provide a magneto-optical recording medium capable of accurately reproducing information recorded on a memory film.

[0016]

According to the first aspect of the present invention, there is provided a magneto-optical recording medium comprising a substrate having at least a reproducing film made of a perpendicular magnetic film and a reproducing intermediate film made of an in-plane magnetic film.
In this embodiment, a reproduction auxiliary film made of an in-plane magnetic film and a memory film made of a perpendicular magnetic film are sequentially formed. Among them, the reproduction intermediate film is a film whose Curie temperature is lower than both the Curie temperature of the reproduction film and the Curie temperature of the memory film. Further, the Curie temperature of the reproduction auxiliary film is lower than the Curie temperature of the reproduction film or the Curie temperature of the memory film, and the temperature at which the in-plane magnetization state changes to the perpendicular magnetization state is the temperature of the reproduction intermediate film. The film is higher than the temperature at which the in-plane magnetization state changes to the perpendicular magnetization state.

According to a second aspect of the present invention, in the magneto-optical recording medium according to the first aspect, the intermediate reproduction film and the auxiliary reproduction film are made of a rare earth metal and a transition metal, and the sublattice magnetization of the rare earth metal is changed. Are predominant, and the ratio of the rare earth metal in the reproduction assisting film is higher than the ratio of the rare earth metal in the reproduction intermediate film. According to a third aspect of the present invention, in the magneto-optical recording medium according to the first or second aspect, the thickness of the reproduction auxiliary film is set to be larger than 0.2 nm.
It is thinner than 0 nm.

According to a fourth aspect of the present invention, in the magneto-optical recording medium according to any one of the first to third aspects,
The sum of the thickness of the reproduction intermediate film and the thickness of the reproduction auxiliary film is 40 n
It is thicker than m. According to a fifth aspect of the present invention, in the magneto-optical recording medium according to any one of the first to fourth aspects, the Curie temperature of the reproduction auxiliary film is set to the same value as the Curie temperature of the reproduction intermediate film. It is.

According to a sixth aspect of the present invention, in the magneto-optical recording medium according to any one of the first to fifth aspects,
A cut film made of a perpendicular magnetization film is formed between the memory film and the auxiliary reproduction film. This cut film has a Curie temperature lower than either the Curie temperature of the reproduction auxiliary film or the Curie temperature of the reproduction intermediate film, and is lower than the temperature at which the in-plane magnetization state of the reproduction intermediate film changes to the perpendicular magnetization state. High film.

According to a seventh aspect of the present invention, in the magneto-optical recording medium according to any one of the first to sixth aspects,
A recording film made of a perpendicular magnetization film, a switching film made of a perpendicular magnetization film, and an initialization film made of a perpendicular magnetization film are sequentially formed on the opposite side of the memory film from the substrate. The Curie temperature of the recording film is higher than the Curie temperature of the memory film, the Curie temperature of the switching film is at least lower than the Curie temperature of the memory film, and the Curie temperature of the initialization film is higher than the Curie temperature of the recording film. high.

According to an eighth aspect of the present invention, in the magneto-optical recording medium according to the seventh aspect, an intermediate film made of an in-plane magnetized film is formed between the memory film and the recording film.

(Function) According to the magneto-optical recording medium of the first aspect, information can be recorded on the memory film by setting the memory film at a temperature higher than its Curie temperature at the time of recording information. . Further, by irradiating the reproducing light at the time of reproducing the information, the temperature in the beam spot is lower than the Curie temperature of the reproducing film or the Curie temperature of the memory film, and the Curie temperature of the reproducing intermediate film and the reproducing assisting temperature. A high temperature region higher than any of the Curie temperatures of the film, and a temperature lower than any of the Curie temperature of the reproducing intermediate film and the Curie temperature of the auxiliary reproducing film and a temperature at which the in-plane magnetization state of the reproducing intermediate film changes to the perpendicular magnetization state. It is possible to generate a temperature distribution that can be divided into three regions: a high medium temperature region and a low temperature region lower than the temperature at which the in-plane magnetization state of the reproducing intermediate film changes to the perpendicular magnetization state. At this time, in the high temperature region, the reproduction intermediate film and the reproduction auxiliary film are in a state of demagnetization while information is still recorded in the memory film. Also,
In the above-mentioned medium temperature region, the intermediate reproduction film is in a perpendicular magnetization state, and the auxiliary reproduction film is in a perpendicular magnetization state under the influence of the adjacent memory film. Further, in the low temperature region, the auxiliary reproduction film is stably maintained in the in-plane magnetization state, and the intermediate reproduction film is stably maintained in the in-plane magnetization state under the influence of the adjacent auxiliary reproduction film. Therefore, information recorded on the memory film can be masked in the high-temperature region and the low-temperature region. Further, in the medium temperature region, information recorded on the memory film can be transferred to a reproducing film and reproduced.

According to the magneto-optical recording medium of the present invention, the temperature at which the in-plane magnetization state of the auxiliary reproduction film changes to the perpendicular magnetization state is determined by changing the in-plane magnetization state of the reproduction intermediate film to the perpendicular magnetization state. It can be higher than the changing temperature. Therefore, at the time of reproducing information, in the low temperature region, the reproduction auxiliary film is stably maintained in the in-plane magnetization state. As a result, the reproduction intermediate film, whose in-plane magnetization state tends to be unstable in the low temperature region, is also stably maintained in the in-plane magnetization state under the influence of the adjacent auxiliary reproduction film. Therefore, the information recorded in the memory film can be masked not only in the high-temperature region but also in the low-temperature region. In the medium-temperature region, the information recorded in the memory film is transferred to the reproducing film and reproduced. can do.

According to the magneto-optical recording medium of the third aspect, at the time of reproducing information, the magnetization of the memory film is sufficiently transferred to the auxiliary reproduction film by the exchange coupling force in the medium temperature region. Therefore, the information recorded on the memory film can be transferred to the reproducing film and reproduced reliably.
According to the magneto-optical recording medium of the fourth aspect, at the time of reproducing information, the transmission of the magnetostatic coupling force between the reproducing film and the memory film can be reliably cut off in the high temperature region.
For this reason, the magnetization of the reproducing film in the high temperature region can be surely set to a constant perpendicular magnetization state regardless of the information recorded in the memory film. Therefore, the information recorded on the memory film can be transferred to the reproducing film only in the above-mentioned medium temperature region, and can be reproduced reliably.

According to the magneto-optical recording medium of the fifth aspect, when reproducing information, the reproduction intermediate film and the reproduction auxiliary film are in the magnetization disappearing state at the same temperature, so that the above-mentioned high temperature region and medium temperature region are not separated. The boundaries can be defined. Therefore, the information recorded on the memory film can be transferred to the reproducing film only in the above-mentioned medium temperature region, and can be reproduced reliably. According to the magneto-optical recording medium of the sixth aspect, by reducing the power of the reproducing light irradiated at the time of reproducing the information, both the magnetization of the reproducing intermediate film and the magnetization of the reproducing auxiliary film disappear in the high temperature region. Even if there is a mixed portion and a portion where the magnetizations of the reproducing intermediate film and the auxiliary reproducing film are both in the perpendicular magnetization state, the memory film is formed by the cut film in which the magnetization disappears in any part of the high-temperature region. The information recorded in the memory film can be masked, and the information in the memory film can be reliably reproduced only in the medium temperature region.

According to the magneto-optical recording medium of the present invention, at the time of recording information, the information can be overwritten on the memory film by the actions of the recording film, the switching film and the initialization film. Also, when reproducing information, the information overwritten on the memory film is masked in the high-temperature region and the low-temperature region by the function of the reproduction film, the reproduction intermediate film, and the reproduction auxiliary film (and the cutting film). Can be. Similarly, the information overwritten on the memory film can be transferred to the reproducing film and reproduced in the medium temperature region.

According to the magneto-optical recording medium of the present invention, at the time of recording information, the information can be overwritten on the memory film by the operation of the intermediate film, the recording film, the switching film and the initialization film. . Also, when reproducing information, the information overwritten on the memory film is masked in the high-temperature region and the low-temperature region by the function of the reproduction film, the reproduction intermediate film, and the reproduction auxiliary film (and the cutting film). Can be. Similarly, the information overwritten on the memory film is stored in the above-mentioned medium temperature region.
It can be reproduced by transferring it to a reproduction film.

[0028]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a sectional view showing a configuration of a magneto-optical disk 10 according to a first embodiment. The first embodiment corresponds to claims 1 to 5.

The magneto-optical disk 10 is a rewritable disk, and the substrate 2 is moved downward from above in FIG.
1, a protective film 22, a reproducing film 11, a reproducing intermediate film 12, a reproducing auxiliary film 13, a memory film 14, and a protective film 23 are sequentially formed. Of these, the memory film 14
Is a film on which information is recorded. The reproduction film 11, the reproduction intermediate film 12, and the reproduction auxiliary film 13 are formed by a memory film 14
This is a film that performs an operation of reproducing information recorded in the. The protection films 22 and 23 are films that protect the magnetic films 11 to 14.

Here, the composition, film thickness and function of each of the magnetic films 11 to 14 and the protective films 22 and 23 constituting the magneto-optical disk 10 will be described. In addition, each of these magnetic films 11 to
14, the protective films 22 and 23 are formed by a well-known sputtering method. The memory film 14 is made of terbium (Tb) which is a rare earth metal, iron (Fe) which is a transition metal,
It is composed of cobalt (Co). The composition of the memory film 14 is represented by atomic percentage, Tb is 20 atomic%, Fe is
Is 64 atomic% and Co is 16 atomic% (hereinafter, the atomic percentage of the composition is represented as Tb20Fe64Co16). The thickness D14 of the memory film 14 is 50 nm.

The memory film 1 having such composition and film thickness
Reference numeral 4 denotes a perpendicular magnetization film in which the magnetization is oriented perpendicular to the film surface (vertical direction in FIG. 1). The memory film 14 has
Rare earth metal (RE) sublattice magnetization is downward and transition metal (T
M) There are a state where the sublattice magnetization is upward and a state where the RE sublattice magnetization is upward and the TM sublattice magnetization is downward. Information is recorded by these two states.

The memory film 14 has a compensation temperature T
h14 is the room temperature Tr (corresponding to the temperature of the magneto-optical disk 10 when no recording light or reproduction light is irradiated. For example, 20
C. to 30 C.). Therefore, the memory film 14
At room temperature Tr, the RE sub-lattice magnetization and the TM sub-lattice magnetization oppose each other, and the entire magnetization is almost zero irrespective of the recorded information.

When information is reproduced, the memory film 14 loses its balance between the RE sub-lattice magnetization and the TM sub-lattice magnetization as its temperature rises due to the irradiation of the reproducing light (for example, the TM sub-lattice magnetization). The magnetization is larger than the RE sublattice magnetization), and the overall magnetization increases while maintaining the state of perpendicular magnetization. The Curie temperature Tc14 of the memory film 14 is about 260 ° C. due to the above composition. This Curie temperature Tc14 (260
° C) is higher than at least the Curie temperature Tc12 of the reproduction intermediate film 12 and the Curie temperature Tc13 of the reproduction auxiliary film 13, which will be described later. The Curie temperature Tc14 is higher than the highest temperature (corresponding to a temperature T2 to be described later) that is raised by the irradiation of the reproduction light when reproducing information.

Further, since the memory film 14 has the above composition, it has a higher coercive force than any of the other magnetic films 11 to 13. The reproduction film 11 is composed of gadolinium (Gd), which is a rare earth metal, and Fe, Co, which are transition metals. The composition of the reproducing film 11 is Gd25Fe60Co
It is 15. The thickness D11 of the reproducing film 11 is 30 nm.

The regenerated film 11 having such a composition and thickness is as follows.
Is a perpendicular magnetization film in which the magnetization is vertically oriented, like the memory film 14 described above. Note that the magnetization of the reproduction film 11 is maintained in a perpendicular magnetization state even when the temperature is increased by irradiation of the reproduction light. Further, since the reproducing film 11 has the above composition, its Curie temperature Tc11
Are at least the Curie temperature Tc12 (230 ° C.) of the reproduction intermediate film 12 and the Curie temperature T
It is higher than any of c13 (130 ° C). Also, the Curie temperature Tc11 is higher than the highest temperature (corresponding to a temperature T2 to be described later) raised by the irradiation of the reproduction light, similarly to the Curie temperature Tc14 of the memory film 14 described above.

The reproducing intermediate film 12 is composed of Gd which is a rare earth metal and Fe which is a transition metal. The composition of the reproducing intermediate film 12 is Gd30Fe70, and the RE sublattice magnetization is dominant. The thickness D12 of the reproducing intermediate film 12
Is 40 nm. The reproducing intermediate film 12 having such a composition and film thickness is an in-plane magnetization film in which the magnetization is oriented in-plane (in the horizontal direction in FIG. 1) at room temperature Tr.

Since the reproducing intermediate film 12 has the above composition, its magnetization changes from the in-plane magnetization state to the perpendicular magnetization state at the predetermined temperature Tx12 higher than the room temperature Tr. The predetermined temperature Tx12 is around 130 ° C. (for example, ° C ~ C).

Further, the Curie temperature Tc12 of the reproduced intermediate film 12 becomes about 230 ° C. due to the above composition. This Curie temperature Tc12 (230 ° C.) is lower than both the Curie temperature Tc11 of the reproduction film 11 and the Curie temperature Tc14 of the memory film 14 described above. The reproduction auxiliary film 13 is composed of Gd, which is a rare earth metal, and F, which is a transition metal.
e, Co. The composition of the reproduction auxiliary film 13 is Gd35Fe62Co3, and
Similar to 2, the RE sublattice magnetization is dominant. The thickness D13 of the reproduction assisting film 13 is 10 nm.

The reproduction assisting film 1 having such composition and film thickness
Reference numeral 3 denotes an in-plane magnetized film in which the magnetization is oriented in-plane, similarly to the above-mentioned reproduction intermediate film 12, which is a room temperature Tr. Since the auxiliary reproduction film 13 has the above composition, its magnetization changes from an in-plane magnetization state to a perpendicular magnetization state at a predetermined temperature Tx13 higher than the room temperature Tr. Here, the regeneration assisting film 13
The composition of the rare earth metal (Gd) (35 at%) is higher than the rare earth metal (Gd) ratio (30 at%) of the reproduction intermediate film 12. In general, in a film in which the RE sublattice magnetization is dominant, the temperature (predetermined temperature Tx) at which the magnetization changes from the in-plane magnetization state to the perpendicular magnetization state increases as the ratio of the rare earth metal increases. For this reason, the predetermined temperature Tx13 of the auxiliary reproduction film 13 is higher than the predetermined temperature Tx13 of the intermediate reproduction film 12.
12 (130 ° C). Therefore, the regeneration assisting film 1
No. 3 can maintain the magnetization in an in-plane magnetization state up to a temperature higher than that of the reproduction intermediate film 12.

The Curie temperature Tc13 of the auxiliary regeneration film 13 is about 230 ° C. due to the above composition. This Curie temperature Tc13 (230 ° C.) is substantially the same as the Curie temperature Tc12 of the reproduced intermediate film 12 described above. The Curie temperature Tc13 is lower than either the Curie temperature Tc11 of the reproduced film 11 or the Curie temperature Tc14 of the memory film 14, similarly to the reproduced intermediate film 12.

The protective films 22 and 23 are made of silicon nitride, and each of the film thicknesses D22 and D23 is 70 nm. Substrate 2
Reference numeral 1 denotes a glass substrate (86 mm in diameter) formed by a 2P (photo-polymerization) method, and a guide groove is spirally formed on one surface thereof. Next, an operation of recording information on the memory film 14 of the rewritable magneto-optical disk 10 configured as described above will be described with reference to FIGS. In FIG. 2, each of the magnetic films 11 to
The arrows indicate the direction of the TM sublattice magnetization to indicate the state of magnetization of No. 14.

In this rewritable magneto-optical disk 10,
The information recording operation is performed after the information already written in the memory film 14 is temporarily erased (initialization of the magneto-optical disk 10). Here, the magneto-optical disk 10
The description of the initialization operation is omitted. When the initialization of the magneto-optical disk 10 is completed, the memory film 14
Is a state in which the TM sublattice magnetization is uniformly aligned in the erasing direction (downward in FIG. 2) (hereinafter, referred to as an “initial state”).

In recording information, the initialized magneto-optical disk 10 is irradiated with recording light 31 from a semiconductor laser (wavelength: 680 nm) of a recording / reproducing device (not shown) (FIG. 2). At this time, the power (for example, 10 mW) of the recording light 31 is intermittent (duty ratio 30%) according to the information to be recorded. The recording light 31 is an objective lens (numerical aperture 0.55) of a recording / reproducing device (not shown).
Is focused to the diffraction limit. In this case, the beam spot 31 of the recording light 31 on the magneto-optical disk 10
The diameter of A is about 1.1 μm.

In recording information, a recording magnetic field Hw (for example, 300 (Oe)) of a constant magnitude generated from a magnetic coil of a recording / reproducing apparatus (not shown) is continuously applied to the beam spot 31A. (FIG. 2). The direction of the recording magnetic field Hw is opposite to the direction (erasing direction) of the TM sublattice magnetization of the memory film 14 in the initial state (recording direction, upward in FIG. 2).

Further, when recording information, the magneto-optical disk 10 is rotated at a constant linear velocity (for example, 9 m / sec) by a motor of a recording / reproducing device (not shown), and the disk moving direction 10A (FIGS. 2 and 3). (To the left as indicated by the arrow in FIG. 3) while traversing the beam spot 31A. When the recording light 31 (10 mW) is actually irradiated, a temperature distribution occurs on the magneto-optical disk 10. At this time, the magneto-optical disk 10 has a Curie temperature Tc14 (260 ° C.) of the memory film 14 only in a small area 31B located near the center of the beam spot 31A.
Is heated to a higher temperature T1 (hereinafter referred to as “recording temperature”).

In the area 14B of the memory film 14 heated to the recording temperature T1 (hereinafter referred to as "heating area"), the temperature has reached the Curie temperature Tc14.
Once the magnetization disappears. When the magneto-optical disk 10 rotates, the heating area 14B, which has been in the small area 31B, moves in the disk moving direction 10A and deviates from the beam spot 31A. Then, the temperature of the heating area 14B gradually decreases from the recording temperature T1 toward the room temperature Tr.

In the heating area 14B, when the temperature starts to decrease from the recording temperature T1, the magnetization starts to recover. At this time, the magnetization of the heating region 14B is affected by the continuously applied recording magnetic field Hw, and the magnetization is reversed from the above initial state (the TM sublattice magnetization changes in the recording direction (FIG. 2).
(Medium, upward)). When the temperature of the heating region 14B further decreases and reaches near the room temperature Tr, the heating region 14B
The coercive force of B increases.

Therefore, the magnetization of the heating region 14B which has been in the recording state due to the effect of the recording magnetic field Hw is maintained in the recording state (the TM sublattice magnetization is in the recording direction) by its own coercive force. Thus, one recording mark 14A smaller than the beam spot 31A is formed (the mark length is 0.3 μm).

Note that the recording light 31 is intermittently irradiated, and the memory film 14
Is maintained in the above initial state (the TM sublattice magnetization is in the erasing direction). Therefore, by irradiating the magneto-optical disk 10 with the recording light 31 while interrupting the power in accordance with the information to be recorded, the beam spot 3
The recording marks 14A, 14A,... Smaller than 1A can be sequentially formed on the memory film 14.

Here, the interval between the recording marks 14A, 14A,...
Is determined by the rotation speed of the
About. Thus, in the rewritable magneto-optical disk 10, the information (the plurality of recording marks 14A, 14A) can be read.
A,...) Can be recorded at a high density (brush tip recording method).

At the time of recording the above information, the magnetization of the other magnetic films 11 to 13 disappears once in the small area 31B in the beam spot 31A, similarly to the memory film 14 described above. However, when the temperature subsequently decreases and reaches near the room temperature Tr, the magnetizations of the reproduction intermediate film 12 and the reproduction auxiliary film 13 of the in-plane magnetization film return to the in-plane magnetization state and become stable at the room temperature Tr (FIG. 2). At room temperature Tr, the magnetization of the reproducing film 11 of the perpendicular magnetization film is adjusted to a constant perpendicular magnetization state as the magnetizations of the reproduction intermediate film 12 and the auxiliary reproduction film 13 return to the in-plane magnetization state. When it reaches the vicinity of Tr, it is stabilized in that state (FIG. 2).

Next, the operation of reproducing the information on the rewritable magneto-optical disk 10 on which high-density information is recorded as described above will be described with reference to FIGS. In FIG. 4, the direction of the TM sublattice magnetization is indicated by an arrow in order to represent the state of magnetization of each of the magnetic films 11 to 14.

When reproducing information, the magneto-optical disk 1
0 is continuously irradiated with a reproduction light 41 of a constant power (for example, 3.5 mW) from a semiconductor laser of a recording / reproducing apparatus (not shown) (FIG. 4). The reproduction light 41 is applied to the magneto-optical disk 10 in a state of linearly polarized light. In reproducing information, a reproducing magnetic field Hr of a constant magnitude generated from a magnetic coil of a recording / reproducing device (not shown) is continuously applied to the beam spot 41A of the reproducing light 41 (FIG. 4). . The direction of the reproducing magnetic field Hr is opposite to the direction of the recording magnetic field Hw (recording direction) (erasing direction). The magnitude of the reproducing magnetic field Hr is smaller than the value of the reproducing magnetic field required for the conventional double mask reproduction (for example, 100), as described later.
(Oe)). Therefore, the magnetic coil of the recording / reproducing apparatus can be configured with a small number of turns, and the power source can be reduced.

Further, in reproducing the information, the magneto-optical disk 10 is rotated at the same linear velocity (for example, 9 m / sec) as the above-mentioned recording, and the disk moving direction 10
A (left side indicated by an arrow in FIGS. 4 and 5) moves while traversing the beam spot 41A. When the reproduction light 41 is actually irradiated, a temperature distribution occurs in the magneto-optical disk 10. At this time, the heat received by the continuous irradiation of the reproducing light 41 accumulates on the magneto-optical disk 10, and the temperature thereof becomes high in the elongated region 41B along the disk moving direction 10A.

Of such an elongated area 41B, an area 41C (the elongated area 41B and the beam spot 4B) located behind (to the right in FIGS. 4 and 5) in the disk moving direction 10A.
1A, the reproduction light 41 is still irradiated. Here, since the reproduction of information is performed by detecting the component of the reproduction light 41 reflected by the beam spot 41A, the area 41C of the above-described elongated area 41B is used.
Only the reproduction operation is involved. Therefore, the operation will be described below focusing on the area 41C.

This area 41C has a beam spot 41A.
Of the disk moving direction 10A (left side in FIGS. 4 and 5), the reproduced light 41 is longer than the area 41D located behind by the amount of the front. It has been irradiated. Therefore, of the beam spot 41A, the area 41C located in the front in the disk moving direction 10A is the area 4C located in the rear.
More heat than 1D has accumulated and the temperature is higher.

Further, there is also a temperature distribution in the area 41C, and the temperature is higher in the front (small semicircular area 41F) in the disk moving direction 10A than in the rear (area 41E). This is because the reproduction light 41 is irradiated to the front (region 41F) for a long time, and a large amount of heat has already been accumulated. As described above, in the beam spot 41A, there is a temperature distribution in which the temperature gradually decreases from the front to the rear in the disk moving direction 10A, and at a certain temperature, a small semicircular region 41F (hereinafter, referred to as a small semicircular region 41F). 3 referred to as a “high temperature region”, a region 41E (hereinafter referred to as a “medium temperature region”), and a region 41D (hereinafter referred to as a “low temperature region”).
Can be divided into two areas.

In the first embodiment, the reproduction light 41
By the irradiation of (3.5 mW), in the high temperature region 41F,
A temperature T2 higher than 230 ° C. (the Curie temperature Tc12 of the reproduction intermediate film 12 and the Curie temperature Tc13 of the reproduction auxiliary film 13)
Becomes In the middle temperature region 41E, the temperature T3 is lower than 230 ° C. and higher than 130 ° C. (the predetermined temperature Tx12 of the reproducing intermediate film 12). Further, in the low temperature region 41D,
The temperature T4 is lower than 130 ° C.

As described above, three regions 41 having different temperatures are used.
Beam spot 41A divided into D, 41E and 41F
4, the magnetization of each of the magnetic films 11 to 14 is in the state described below, as shown in FIG.

First, the magnetization of the memory film 14 is stably held in any of the regions 41D, 41E, and 41F in the beam spot 41A as it is recorded. This is because the temperature in the beam spot 41A (the highest temperature is the temperature T2 in the high temperature region 41F, and the lowest temperature is the temperature T4 in the low temperature region 41D) is lower than the Curie temperature Tc14 (260 ° C.) of the memory film 14. This is because the magnetization does not disappear and the coercive force is sufficiently high to retain information.

The magnetization of the reproducing film 11 is maintained in the perpendicular magnetization state in any of the regions 41D, 41E and 41F in the beam spot 41A. This is because the temperature in the beam spot 41A (lower than the temperature T2 and higher than the temperature T4) is higher than the Curie temperature Tc11 of the reproducing film 11.
Because it is lower. On the other hand, the magnetization of the reproducing intermediate film 12
The magnetization of the reproduction auxiliary film 13 is controlled by the beam spot 41A.
The low-temperature area 41D (temperature T4), the medium-temperature area 41E (temperature T3), and the low-temperature area 41F (temperature T2) are in different states according to the temperatures.

Here, the state of magnetization of the reproduction intermediate film 12, the state of magnetization of the reproduction auxiliary film 13, and the operation of reproducing information will be described for each of the regions 41D, 41E and 41F in the beam spot 41A. In the low temperature region 41D, the temperature T4 is a predetermined temperature Tx12 (130 ° C.) at which the reproduction intermediate film 12 changes from the in-plane magnetization state to the perpendicular magnetization state, and further, the reproduction auxiliary film 13 is changed from the in-plane magnetization state to the perpendicular magnetization state. Is lower than the predetermined temperature Tx13 (Tx13> Tx12).

Therefore, the reproduction auxiliary film 13 has a strong tendency that its magnetization is in an in-plane magnetization state. At this time, the magnetization of the reproduction auxiliary film 13 receives an exchange coupling force from the adjacent memory film 14, but has a sufficiently strong tendency to be in the in-plane magnetization state, and does not change to the perpendicular magnetization state. The state is maintained. On the other hand, as described above, the predetermined temperature Tx12 at which the in-plane magnetization state changes from the in-plane magnetization state to the perpendicular magnetization state is lower than the predetermined temperature Tx13 of the auxiliary reproduction film 13, so that the magnetization of the reproduction intermediate film 12 also tends to be in the in-plane magnetization state. Relatively weak.

When the in-plane magnetization state is relatively weak as described above, the reproduction intermediate film 12 maintains the in-plane magnetization state stably without the adjacent magnetic film, but has the adjacent magnetic film. When formed, the in-plane magnetization state of the magnetization tends to be unstable due to the exchange coupling force from the magnetic film. At this time, when the adjacent magnetic film is the in-plane magnetic film, the magnetization of the reproducing intermediate film 52 is maintained in the in-plane magnetization state, but when the perpendicular magnetic film is adjacent, the magnetization is in the perpendicular magnetization state. And easily.

However, in the magneto-optical disk 10 of the first embodiment, the auxiliary reproduction film 13 is
(The magnetization tends to be in the in-plane magnetization state), the magnetization of the reproduction intermediate film 12 is affected by the exchange coupling force from the auxiliary reproduction film 13, and the in-plane magnetization state is stabilized. (Fig. 4). As described above, the reproduction intermediate film 12 and the reproduction auxiliary film 13 both have a stable in-plane magnetization state, so that the exchange coupling force from the memory film 14 does not act on the reproduction film 11, and as a result, the low temperature In the region 41D, a mask is reliably formed, and the magnetization of the memory film 14 is not transferred to the reproduction film 11.

When the in-plane magnetization state of the reproduction intermediate film 12 is relatively weak, the perpendicular magnetization state of the reproduction film 11 also tends to be unstable. Although a large reproducing magnetic field (500 (Oe)) had to be applied to align the perpendicular magnetization state of the reproducing film 11 in the erasing direction, both the reproducing intermediate film 12 and the reproducing auxiliary film 13 were stable as described above. In the case of the in-plane magnetization state, even if the reproducing magnetic field Hr applied to the reproducing film 11 in the low temperature region 41D is small (100 (Oe)), the TM sublattice magnetization of the reproducing film 11 can be easily changed in the erasing direction. (Downward in FIG. 4).

In the high temperature region 41F, the temperature T2
Is higher than 230 ° C. (Curie temperature Tc12 of the regeneration intermediate film 12 and Curie temperature Tc13 of the regeneration auxiliary film 13).
The magnetizations of the reproduction intermediate film 12 and the reproduction auxiliary film 13 have both disappeared (FIG. 4). Therefore, in the high temperature region 41F, the exchange coupling force between the memory film 14 and the reproduction film 11 is disconnected.

Further, in the high temperature region 41F, the magnetostatic coupling force between the memory film 14 and the reproducing film 11 is also cut. This is because the distance d1 between the memory film 14 and the reproducing film 11 is a value (50 nm) at which the magnetostatic coupling force does not act.
Because it is kept in. Incidentally, the distance d1 is determined by the sum of the film thickness D13 (10 nm) of the reproduction auxiliary film 13 and the film thickness D12 (40 nm) of the reproduction intermediate film 12.

As described above, in the high temperature region 41F, since neither exchange coupling force nor magnetostatic coupling force acts between the memory film 14 and the reproduction film 11, the magnetization of the memory film 14 is not transferred to the reproduction film 11. At this time, the reproducing film 11 in the high temperature region 41F has a perpendicular magnetization state, but its TM sublattice magnetization is uniformly changed in the erasing direction under the influence of the continuously applied reproducing magnetic field Hr. (Downward in FIG. 4).

In the middle temperature region 41E, the temperature T3
However, since the temperature is higher than 130 ° C. (the predetermined temperature Tx12 of the reproducing intermediate film 12), the magnetization of the reproducing intermediate film 12 changes from the in-plane magnetization state (horizontal direction in FIG. 4) and the perpendicular magnetization state (FIG. 4).
Middle, vertical). The temperature T3 of the middle temperature region 41E is equal to the Curie temperature Tc13 (23
0 ° C.), the magnetization of the auxiliary reproduction film 13 in the medium temperature region 41E is in an in-plane magnetization state, similarly to the low temperature region 41D.

However, since the temperature of the medium temperature region 41E (temperature T3) is higher than that of the low temperature region 41D (temperature T4), the auxiliary reproduction film 13 in the medium temperature region 41E is in the state of the low temperature region 41D. In comparison, the tendency of the magnetization to become an in-plane magnetization state is weakened. Here, the auxiliary reproduction film 13 in the intermediate temperature region 41E is maintained in the in-plane magnetization state if there is no adjacent magnetic material, but if the adjacent magnetic film is formed, the reproduction auxiliary film 13 is removed from the magnetic film. , The in-plane magnetization state of the magnetization becomes unstable.

Therefore, in the medium temperature region 41E, the magnetization of the auxiliary reproduction film 13 is affected by the exchange coupling force from the adjacent memory film 14 and the intermediate reproduction film 12 (both of which are perpendicularly magnetized). Becomes At this time, the magnetization of the reproduction assisting film 13 has the same direction following the magnetization of the memory film 14. The transfer of the magnetization of the memory film 14 in the middle temperature region 41E is performed by the thickness D13 of the auxiliary reproduction film 13.
(10 nm) corresponds to the film thickness D12 (40 n
m), which is sufficient.

The magnetization of the reproduction intermediate film 12 adjacent to the auxiliary reproduction film 13 has the same direction as the magnetization of the memory film 14 due to the exchange coupling force from the auxiliary reproduction film 13. Further, the magnetization of the reproducing film 11 adjacent to the reproducing intermediate film 12 has the same direction as the magnetization of the memory film 14 due to the exchange coupling force from the reproducing intermediate film 12. At this time, the reproducing magnetic field Hr is also applied to the intermediate temperature region 41E. However, in determining the direction of magnetization of the reproducing film 11 in the intermediate temperature region 41E, the reproducing magnetic field Hr is more strongly applied to the reproducing intermediate film 12 than the magnetostatic coupling force of the reproducing magnetic field Hr. Exchange coupling force greatly contributes.

As described above, in the three regions 41D, 41E and 41F in the beam spot 41A, the reproduction intermediate film 1
2. The auxiliary reproduction film 13 is in a different state depending on the temperature, and only in the middle temperature region 41E, the magnetization of the memory film 14 is changed from the auxiliary reproduction film 13 → the intermediate reproduction film 12 → the reproduction film 11
Are transferred in order. In the low temperature region 41D, a mask (low temperature mask) is formed by the stable in-plane magnetization state of the reproduction intermediate film 12 and the reproduction auxiliary film 13 described above.
Further, in the high temperature region 41F, the above-mentioned reproduced intermediate film 12,
A mask (high-temperature mask) is formed according to the magnetization disappearance state of the reproduction auxiliary film 13. And these low temperature regions 41
D, in the high temperature region 41F, as described above, the reproduction film 11
Are uniformly aligned in the erasing direction.

By the way, the size of the medium temperature region 41E where the transfer of the magnetization of the memory film 14 to the reproducing film 11 is performed is such that one small recording mark 14A formed on the memory film 14 at a constant interval (0.3 μm). Just enough to fit. Specifically, the size of the intermediate temperature region 41E is
Composition of playback intermediate film 12 (Gd30Fe70), playback assisting film 1
3, the composition (Gd35Fe62Co3) and the reproduction power (3.5
mW) and the rotational speed of the disk (9 m / sec).

Therefore, of the plurality of recording marks 14A, 14A,... Formed at a fixed narrow interval on the memory film 14, only one of the recording marks 14A is the medium temperature area 41E.
In this case, the reproduction auxiliary film 13 (transfer mark 13A), the reproduction intermediate film 12 (transfer mark 12A), and the reproduction film 11 (transfer mark 11A) are sequentially transferred. As described above, in the beam spot 41A, one transfer mark 11A (the TM sublattice magnetization is in the recording direction) is formed only in the medium temperature region 41E, and the low temperature region 41D and the high temperature region 41F are formed.
Since the TM sublattice magnetization is uniformly aligned in the erasing direction, the component (reflected light) of the reproduction light 41 reflected by the beam spot 41A is detected, and thus the memory film 14 is detected.
Can be accurately reproduced (for example, so as not to cause crosstalk) from among the plurality of recording marks 14A, 14A,.

The above-described reproducing operation is sequentially performed in the disk moving direction 10A with the rotation of the magneto-optical disk 10, whereby the memory film 14 of the magneto-optical disk 10 is rotated.
Can be reproduced one by one in order. As described above, according to the rewritable magneto-optical disk 10 of the first embodiment, between the memory film 14 and the reproducing film 11, the reproducing intermediate film 12 (in-plane magnetized film, the predetermined temperature Tx12), Auxiliary film 13 (in-plane magnetized film, predetermined temperature Tx13> predetermined temperature Tx12)
Thus, the low-temperature mask in the low-temperature region 41D can be surely formed with the reproducing magnetic field Hr as small as can be generated by the current recording / reproducing apparatus. As a result, the information of the memory film 14 can be masked not only in the low temperature region 41D but also in the high temperature region 41F, and the information of the memory film 14 is transferred only in the middle temperature region 41E, so that the double mask reproduction becomes more practical.

Therefore, according to the rewritable magneto-optical disk 10 of the first embodiment, information (a plurality of recording marks 14A, 14A,
..) Can be accurately reproduced one by one. When the carrier-to-noise intensity ratio (CN ratio) of this rewritable magneto-optical disk 10 was actually measured, it was found that a good CN ratio of 45 dB or more was obtained.

The magneto-optical disk 10 of the first embodiment
In the above description, an example in which the thickness D13 of the reproduction auxiliary film 13 is set to 10 nm has been described.
It can be set to any value within a range greater than 0.2 nm and less than 30 nm. When the thickness D13 of the auxiliary reproduction film 13 is within the above range, the transfer of the magnetization of the memory film 14 to the auxiliary reproduction film 13 is sufficiently performed in the medium temperature region 41E. Incidentally, the minimum value 0.2 nm of the thickness D13 of the auxiliary reproduction film 13 corresponds to the thickness of one atom constituting the auxiliary reproduction film 13.

The magneto-optical disk 10 of the first embodiment
In the above, the example in which the sum of the thickness D12 of the reproduction intermediate film 12 and the thickness D13 of the reproduction auxiliary film 13 is set to 50 nm has been described.
This sum can be set to any value as long as it is thicker than 40 nm. If the sum is greater than 40 nm, no magnetostatic coupling force acts between the memory film 14 and the reproduction film 11. Also in this case, it is necessary to set the thickness D13 of the reproduction assisting film 13 to an arbitrary value within the range of greater than 0.2 nm and smaller than 30 nm.

Further, the magneto-optical disk 1 of the first embodiment
In the case of 0, an example of using a pen tip recording method to record information at a high density on the memory film 14 of the magneto-optical disk 10 has been described, but a magnetic field modulation recording method can also be used. However, even when the magnetic field modulation recording method is used, information can be recorded on the memory film 14 at high density.

The magneto-optical disk 10 of the first embodiment
In the above, an example in which a small reproducing magnetic field Hr is applied has been described. However, in the low-temperature region 41D, the influence of the exchange coupling force from the reproducing intermediate film 12 and the reproducing auxiliary film 13 both in a stable in-plane magnetization state is considered. As a result, if the magnetization of the reproducing film 11 becomes a stable in-plane magnetization state, the reproducing magnetic field H
It is not necessary to apply r.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. This second embodiment corresponds to claims 1 to 6. The magneto-optical disk 50 of the second embodiment is also a rewritable disk, and the rewritable magneto-optical disk 1 of the first embodiment is
Double mask reproduction with a small reproduction magnetic field Hr similar to 0 is possible. Also, the magneto-optical disk 5 of the second embodiment
0 means that the reproducing power can be reduced.

First, the magneto-optical disk 50 of the second embodiment
Will be described. The magneto-optical disk 50 according to the second embodiment includes a substrate 61 from the top in FIG.
The protective film 62, the reproducing film 51, the reproducing intermediate film 52, the reproducing auxiliary film 53, the cutting film 54, the memory film 55, and the protective film 6
3 are sequentially formed. In the magneto-optical disk 50 of the second embodiment, each of the magnetic films 51 to 51 described above is used.
Of the 55, the reproduction film 51, the reproduction intermediate film 52, and the reproduction auxiliary film 53 are used for reproducing the information, the reproduction film 11, the reproduction intermediate film 12, and the reproduction auxiliary film 13 of the magneto-optical disk 10 of the first embodiment.
Performs the same operation as.

Here, the magneto-optical disk 5 of the second embodiment
The composition, thickness, and function of each of the films 51 to 55, 62, and 63 constituting 0 will be described. In addition, each of these films 51-
55, 62 and 63 are also formed by a well-known sputtering method. The memory film 55 is made of Tb, which is a rare earth metal.
And transition metals Fe and Co. The composition of the memory film 55 is Tb20Fe64Co16, and the film thickness D55 is 50 nm.

The memory film 5 having such composition and film thickness
Reference numeral 5 denotes a perpendicular magnetization film whose magnetization is oriented perpendicularly to the film surface (vertical direction in FIG. 6). Note that the memory film 55 includes
Rare earth metal (RE) sublattice magnetization is downward and transition metal (T
M) Information is recorded in a state where the sub-lattice magnetization is upward and a state where the RE sub-lattice magnetization is upward and the TM sub-lattice magnetization is downward.

The memory film 55 has its compensation temperature T
h55 is near the room temperature Tr. Therefore, the memory film 5
5 shows that at room temperature Tr, the RE sublattice magnetization and the TM sublattice magnetization antagonize, and the entire magnetization is almost zero irrespective of the recorded information. When information is reproduced, such a memory film 55 loses the balance between the RE sublattice magnetization and the TM sublattice magnetization as the temperature rises due to the irradiation of the reproduction light (for example, when the TM sublattice magnetization becomes RE The magnetization is larger than the sub-lattice magnetization), and the overall magnetization increases while maintaining the state of perpendicular magnetization.

The Curie temperature Tc55 of the memory film 55 is about 260 ° C. due to the above composition. The Curie temperature Tc55 (260 ° C.) is higher than at least the Curie temperature Tc52 of the reproduction intermediate film 52 and the Curie temperature Tc53 of the reproduction auxiliary film 53, which will be described later. The Curie temperature Tc55 is even higher than the highest temperature (corresponding to a temperature T2 to be described later) that is increased by the irradiation of the reproduction light when reproducing information.

Further, since the memory film 55 has the above composition, it has a higher coercive force than any of the other magnetic films 51 to 54. The reproducing film 51 is made of Gd, which is a rare earth metal.
And Fe and Co as transition metals. The composition of the reproducing film 51 is Gd25Fe60Co15, and its thickness D51 is 30 nm.

The reproduction film 51 having such a composition and thickness is as follows.
Is a perpendicular magnetization film in which the magnetization is vertically oriented, like the memory film 55 described above. Note that the magnetization of the reproduction film 51 is maintained in a perpendicular magnetization state even when the temperature is increased by irradiation of the reproduction light. Further, since the reproducing film 51 has the above composition, its Curie temperature Tc51
Are at least the Curie temperature Tc52 (230 ° C.) of the reproduction intermediate film 52 and the Curie temperature Tc of the reproduction auxiliary film 53 described later.
c53 (230 ° C). Also, the Curie temperature Tc51 is higher than the highest temperature (corresponding to a temperature T2 to be described later) raised by the irradiation of the reproduction light, similarly to the Curie temperature Tc55 of the memory film 55 described above.

The reproduction intermediate film 52 is composed of Gd which is a rare earth metal and Fe which is a transition metal. The composition of the reproducing intermediate film 52 is Gd30Fe70, and the RE sublattice magnetization is dominant. Further, the thickness D52 of the reproduction intermediate film 52
Is 40 nm. The reproducing intermediate film 52 having such a composition and thickness is an in-plane magnetization film in which the magnetization is oriented in-plane (in the horizontal direction in FIG. 6) at room temperature Tr.

Since the reproducing intermediate film 52 has the above composition, its magnetization changes from an in-plane magnetization state to a perpendicular magnetization state at a predetermined temperature Tx52 higher than the room temperature Tr. The predetermined temperature Tx52 is around 130 ° C. (for example, ° C ~ C). Further, the reproduced intermediate film 5
2 has a Curie temperature Tc52 of 2 due to the above composition.
It will be about 30 ° C. This Curie temperature Tc52 (230
° C) is the Curie temperature Tc51 of the reproduction film 51 described above,
It is lower than any of the Curie temperatures Tc55 of the memory film 55.

The auxiliary reproduction film 53 is composed of Gd which is a rare earth metal and Fe and Co which are transition metals.
The composition of the reproduction auxiliary film 53 is Gd35Fe62Co3, and the RE sublattice magnetization is dominant similarly to the reproduction intermediate film 52 described above. The thickness D53 of the reproduction assisting film 53 is 10
nm. The regeneration assisting film 5 having such a composition and thickness.
Reference numeral 3 denotes a room temperature Tr, an in-plane magnetization film in which the magnetization is oriented in-plane similarly to the reproduction intermediate film 52 described above.

Since the auxiliary reproduction film 53 has the above composition, its magnetization changes from the in-plane magnetization state to the perpendicular magnetization state at the predetermined temperature Tx53 higher than the room temperature Tr. Here, the ratio of the rare earth metal (Gd) (35 atomic%) in the auxiliary reproduction film 53 is such that the rare earth metal
The composition is higher than the (Gd) ratio (30 atomic%). In general, in a film in which the RE sublattice magnetization is dominant, the temperature (predetermined temperature Tx) at which the magnetization changes from the in-plane magnetization state to the perpendicular magnetization state increases as the ratio of the rare earth metal increases.
Therefore, the predetermined temperature Tx53 of the auxiliary reproduction film 53 is higher than the predetermined temperature Tx52 (130 ° C.) of the intermediate reproduction film 52. Therefore, the auxiliary reproduction film 53 can maintain the magnetization in an in-plane magnetization state up to a higher temperature than the intermediate reproduction film 52.

The Curie temperature Tc53 of the auxiliary regeneration film 53 is about 230 ° C. due to the above composition. The Curie temperature Tc53 (230 ° C.) is substantially the same as the Curie temperature Tc52 of the reproduced intermediate film 52 described above. The Curie temperature Tc53 is lower than the Curie temperature Tc51 of the reproduced film 51 and the Curie temperature Tc55 of the memory film 55, similarly to the reproduced intermediate film 52.

The cutting film 54 is made of T which is a rare earth metal.
b and Fe which is a transition metal. The composition of the cut film 54 is Tb20Fe80, and its thickness D54 is
20 nm. Cutting film 5 having such composition and thickness
Reference numeral 4 denotes a perpendicular magnetization film whose magnetization is oriented perpendicularly to the film surface (vertical direction in FIG. 6), like the memory film 55 and the reproduction film 51 described above.

The cut film 54 has a Curie temperature Tc 54 of about 140 ° C. due to the above composition. The Curie temperature Tc54 (140 ° C.) is lower than the Curie temperature Tc53 (230 ° C.) of the reproduction assisting film 53 and the Curie temperature Tc52 (230 ° C.) of the reproducing intermediate film 52.
Further, the Curie temperature Tc54 (140 ° C.) is higher than the predetermined temperature Tx52 (130 ° C.) of the reproduced intermediate film 52 described above.

The protective films 62 and 63 are made of silicon nitride, and each of the film thicknesses D22 and D23 is 70 nm. Substrate 6
Reference numeral 1 denotes a glass substrate (86 mm in diameter) formed by a 2P (photo-polymerization) method, and a guide groove is spirally formed on one surface thereof. The operation of recording information on the memory film 55 of the rewritable magneto-optical disk 50 configured as described above is the same as the operation of recording information on the memory film 14 of the rewritable magneto-optical disk 10 of the first embodiment. .

That is, in the rewritable magneto-optical disk 50, the TM sublattice magnetization of the memory film 55 is uniformly aligned in the erasing direction (downward in FIG. 6) by the initialization operation (hereinafter referred to as "the memory film 55"). Initial state "). The initialized magneto-optical disk 50 has a recording light (wavelength 680 n) of constant power (for example, 10 mW).
m) is radiated intermittently according to the information (duty ratio 30%). The recording light at this time is converged to the diffraction limit, and the diameter of the beam spot is about 1.1 μm.

When the recording light (10 mW) is actually irradiated, the temperature is higher than the Curie temperature Tc55 (260 ° C.) of the memory film 55 only in a small area (heating area) located near the center of the beam spot. Temperature T1 (recording temperature)
Until magnetization disappears. Then, with the rotation of the magneto-optical disk 50 (for example, 9 m / sec), the heating area deviates from the beam spot. Then, the temperature of the heating area gradually decreases from the recording temperature T1 toward the room temperature Tr.

When the temperature of the heating area starts to decrease from the recording temperature T1, the magnetization starts to recover. At this time, the magnetization of the heated region is affected by the continuously applied recording magnetic field (upward in FIG. 6, the magnitude is, for example, 300 (Oe)), and the recording is inverted from the above initial state. A state (a state in which the TM sublattice magnetization is in the recording direction (upward in FIG. 6)). Thereafter, when the temperature of the heating area reaches the vicinity of the room temperature Tr, the coercive force of the heating area increases, and the magnetization of the heating area which is in the recording state due to the influence of the recording magnetic field changes its recording state (TM side The lattice magnetization is maintained in the recording direction. In this way, one smaller than the beam spot
One recording mark is formed (mark length 0.3μ)
m).

In this way, the magneto-optical disk 50 of the second embodiment can also record information at a high density by the pen tip recording method. Here, the interval between the recording marks is determined by the intermittent interval of the recording light and the rotation speed of the magneto-optical disk 50, and the interval is about 0.3 μm. When recording the above information, the other magnetic films 51 to 55 also
As in the case of the memory film 55, the magnetization once disappears in a small area in the beam spot. However, when the temperature decreases and reaches near the room temperature Tr, the magnetizations of the reproduction intermediate film 52 and the reproduction auxiliary film 53 become in-plane magnetization. The state returns to the stable state, and the regenerated film 5
1. The magnetization of the cutting film 54 returns to the perpendicular magnetization state and stabilizes.

Next, the operation of reproducing information from the rewritable magneto-optical disk 50 on which high-density information is recorded as described above will be described with reference to FIGS. In FIG. 7, the direction of the TM sublattice magnetization is indicated by an arrow in order to represent the state of magnetization of each of the magnetic films 51 to 55. In reproducing the information, the magneto-optical disk 50 is continuously irradiated with a reproducing light 71 of a constant power from a semiconductor laser of a recording / reproducing apparatus (not shown) (FIG. 7). In this case, the power of the reproduction light 71 is set to a value (for example, 2 mW) smaller than the power of the reproduction light 41 emitted when reproducing information from the magneto-optical disk 10 of the first embodiment. The reproduction light 71 is applied to the magneto-optical disk 50 in a state of linearly polarized light.

In reproducing the information, the reproduction light 71
A constant reproducing magnetic field Hr generated from a magnetic coil of a recording / reproducing device (not shown) is continuously applied to the beam spot 71A (FIG. 7). This reproducing magnetic field H
The direction of r is opposite to the direction of the recording magnetic field (recording direction) (erasing direction). The magnitude of the reproducing magnetic field Hr is smaller than the value of the reproducing magnetic field required for the conventional double mask reproduction (for example, 100 (Oe)), as described later. Therefore, the magnetic coil of the recording / reproducing apparatus can be configured with a small number of turns, and the power source can be reduced.

Further, in reproducing the information, the magneto-optical disk 50 is rotated at the same linear velocity (for example, 9 m / sec) as the above-described recording, and the disk moving direction 50 is set.
A (to the left as indicated by the arrows in FIGS. 7 and 8) moves across the beam spot 71A. At the time of reproduction, when the reproduction light 71 is actually irradiated, the movement direction 50A is set in the beam spot 71A on the magneto-optical disk 50 as in the case of the magneto-optical disk 50 of the first embodiment.
From the front to the rear, a certain temperature can be used as a boundary to divide the temperature into three regions: a high temperature region 71F (temperature T2), a medium temperature region 71E (temperature T3), and a low temperature region 71D (temperature T4).

In the second embodiment, the reproduction light 71
By the irradiation of (2 mW), the temperature T2 becomes higher than the Curie temperature Tc54 (140 ° C.) of the cut film 54 in the high temperature region 71F. In the middle temperature region 71E, the cut film 54
The temperature T3 is lower than the Curie temperature Tc54 (140 ° C.) and higher than the predetermined temperature Tx52 (130 ° C.) of the reproduced intermediate film 52. Further, in the low temperature region 71D, the temperature T4 lower than the predetermined temperature Tx52 (130 ° C.) of the reproduction intermediate film 52.
Becomes

As described above, three regions 71 having different temperatures are used.
Beam spot 71A divided into D, 71E and 71F
7, the magnetization of each of the magnetic films 51 to 55 is in the state described below, as shown in FIG. First,
The magnetization of the memory film 55 is stably held in any of the regions 71D, 71E, and 71F in the beam spot 71A, as recorded. this is,
The temperature in the beam spot 71A (the highest temperature is the temperature T2 of the high temperature region 71F, and the lowest temperature is the temperature T4 of the low temperature region 71D) is the Curie temperature Tc55 of the memory film 55.
(260 ° C.), the magnetization does not disappear, and the coercive force is sufficiently high to retain information.

The magnetization of the reproducing film 51 is maintained in the perpendicular magnetization state in any of the regions 71D, 71E and 71F in the beam spot 71A. This is because the temperature in the beam spot 71A (lower than the temperature T2 and higher than the temperature T4) changes the Curie temperature Tc51 of the reproducing film 51.
Because it is lower. On the other hand, the magnetization of the reproducing intermediate film 52,
The magnetization of the reproduction auxiliary film 53 and the magnetization of the cutting film 54 are
The low-temperature area 71D in the beam spot 71A (the temperature T
4), medium temperature area 71E (temperature T3), low temperature area 71F
Each (temperature T2) is in a different state according to the temperature.

Here, for each of the regions 71D, 71E and 71F in the beam spot 71A, the state of magnetization of the reproduction intermediate film 52, the state of magnetization of the reproduction auxiliary film 53, the state of magnetization of the cutting film 54, and the state of information The reproduction operation will be described. In the low temperature region 71D, the temperature T4 is lower than the Curie temperature Tc54 (140 ° C.) of the cut film 54,
The magnetization of No. 4 is maintained in the perpendicular magnetization state without disappearing. At this time, the magnetization of the cut film 54 has the same direction following the magnetization of the memory film 55 due to the influence of the exchange coupling force from the memory film 55 formed adjacently.

In the low temperature region 71D, the temperature T4
However, a predetermined temperature Tx52 (130 ° C.) at which the reproduction intermediate film 52 changes from the in-plane magnetization state to the perpendicular magnetization state, and a predetermined temperature Tx53 (Tx53) at which the reproduction auxiliary film 53 changes from the in-plane magnetization state to the perpendicular magnetization state. > Tx52). Therefore, the reproduction auxiliary film 53 has a strong tendency that its magnetization becomes an in-plane magnetization state. At this time, the magnetization of the reproduction assisting film 53 receives exchange coupling force from the adjacent cut film 54, but has a sufficiently strong tendency to be in the in-plane magnetization state, so that it does not change to the perpendicular magnetization state, and thus has stable in-plane magnetization. The state is maintained.

On the other hand, the reproduction intermediate film 52 has a predetermined temperature Tx at which the in-plane magnetization state changes to the perpendicular magnetization state as described above.
Since 52 is lower than the predetermined temperature Tx53 of the auxiliary reproduction film 53, its magnetization is relatively weak in the in-plane magnetization state. When the in-plane magnetization state is relatively weak as described above, the reproducing intermediate film 52
If there is no adjacent magnetic film, the magnetization is stably maintained in the in-plane magnetization state, but if the adjacent magnetic film is formed, the influence of the exchange coupling force from the magnetic film causes
The in-plane magnetization state of the magnetization tends to be unstable. At this time, when the adjacent magnetic film is the in-plane magnetic film, the magnetization of the reproducing intermediate film 52 is maintained in the in-plane magnetization state, but when the perpendicular magnetic film is adjacent, the magnetization is in the perpendicular magnetization state. And easily.

However, in the magneto-optical disk 50 of the second embodiment, the auxiliary reproduction film 53 is located adjacent to the intermediate reproduction film 52.
(The magnetization tends to be in the in-plane magnetization state), the magnetization of the reproduction intermediate film 52 is affected by the exchange coupling force from the reproduction auxiliary film 53, and the in-plane magnetization state is stabilized. (Fig. 7). As described above, since the reproduction intermediate film 52 and the reproduction auxiliary film 53 both have a stable in-plane magnetization state in the low temperature region 71D, the exchange coupling force from the memory film 55 does not act on the reproduction film 51. ,As a result,
In the low temperature region 71D, a mask is reliably formed, and the magnetization of the memory film 55 is not transferred to the reproduction film 51.

When the in-plane magnetization state of the reproducing intermediate film 52 is relatively weak, the perpendicular magnetization state of the reproducing film 51 also tends to be unstable. Although a large reproducing magnetic field (500 (Oe)) had to be applied to align the perpendicular magnetization state of the reproducing film 51 in the erasing direction, both the reproducing intermediate film 52 and the reproducing auxiliary film 53 became stable as described above. If the in-plane magnetization state exists, even if the reproducing magnetic field Hr applied to the reproducing film 51 in the low temperature region 71D is small (100 (Oe)), the TM sublattice magnetization of the reproducing film 51 can be easily changed in the erasing direction. (Downward in FIG. 7).

In the high temperature region 71F, the temperature T2
Is higher than 140 ° C. (Curie temperature Tc54 of the cut film 54), the magnetization of the cut film 54 has disappeared (FIG. 7). Therefore, in the high temperature region 71F, the exchange coupling force between the memory film 55 and the reproduction film 51 is disconnected. Further, in the high-temperature region 71F, since the power of the reproduction light 71 is small, a part F1 whose temperature is higher than 230 ° C. (the Curie temperature Tc52 of the reproduction intermediate film 52 and the Curie temperature Tc53 of the reproduction auxiliary film 53), And F2.

Then, in the part F1 of the high temperature region 71F,
The temperature is 230 ° C. (the Curie temperature T of the regenerated intermediate film 52)
c52 and the Curie temperature Tc53 of the auxiliary reproduction film 53).
No. 3 has disappeared (FIG. 7). Therefore,
In this part F1, the magnetostatic coupling force between the memory film 55 and the reproducing film 51 is also cut. At this time, the distance d between the memory film 55 and the reproducing film 51 is 70 nm, which is a value such that the magnetostatic coupling force does not act.

In the area F2 other than a part of the high temperature area 71F, the temperature is lower than 230 ° C. (the Curie temperature Tc52 of the reproducing intermediate film 52 and the Curie temperature Tc53 of the reproducing auxiliary film 53) and higher than 140 ° C. Then, the reproduction interlayer 5
2. Both the magnetization of the auxiliary reproduction film 53 changes from the in-plane magnetization state to a perpendicular magnetization state (FIG. 7). However, in F2 other than this part, the memory assisting film 5
3 has no effect of the magnetostatic coupling force.

As described above, in the second embodiment, the reproduction light 7
In the high temperature region 71F, the magnetization F1 of the reproduction intermediate film 52 and the auxiliary reproduction film 53 is perpendicular to the portion F1 in which both the magnetizations of the reproduction intermediate film 52 and the auxiliary reproduction film 53 have disappeared. Except for a part in a magnetized state, F2 is mixed. However, since the magnetization of the cutting film 54 formed between the memory film 55 and the auxiliary reproduction film 53 has disappeared, the magnetization of the memory film 55 may be in any case.
Not transferred to 1.

At this time, the reproduction film 51 in the high temperature region 71F
Has a perpendicular magnetization state, but its TM sublattice magnetization is uniformly aligned in the erasing direction (downward in FIG. 7) under the influence of the continuously applied reproducing magnetic field Hr. State. In the middle temperature region 71E, the temperature T3 is
Since the temperature is lower than the Curie temperature Tc54 (140 ° C.) of the cut film 54, the magnetization of the cut film 54 is maintained in the perpendicular magnetization state without disappearing. At this time, the magnetization of the cut film 54 has the same direction following the magnetization of the memory film 55 due to the influence of the exchange coupling force from the memory film 55 formed adjacently.

In the middle temperature region 71E, the temperature T3
However, since the temperature is higher than 130 ° C. (the predetermined temperature Tx52 of the reproducing intermediate film 52), the magnetization of the reproducing intermediate film 52 changes from the in-plane magnetization state (the horizontal direction in FIG. 7) to the perpendicular magnetization state (FIG. 7).
Middle, vertical). The temperature T3 of the middle temperature region 71E is equal to the Curie temperature Tc53 (23
0 ° C.), the magnetization of the auxiliary reproduction film 53 in the intermediate temperature region 71E is in the in-plane magnetization state, similarly to the low temperature region 71D.

However, since the temperature of the middle temperature region 71E (temperature T3) is higher than that of the low temperature region 71D (temperature T4), the auxiliary reproduction film 53 in the middle temperature region 71E is in the state of the low temperature region 71D. In comparison, the tendency of the magnetization to become an in-plane magnetization state is weakened. Here, the auxiliary reproduction film 53 in the intermediate temperature region 71E is maintained in the in-plane magnetization state if there is no adjacent magnetic material, but if the adjacent magnetic film is formed, the auxiliary magnetic film 53 , The in-plane magnetization state of the magnetization becomes unstable.

Therefore, in the middle temperature region 71E, the magnetization of the auxiliary reproduction film 53 is affected by the exchange coupling force from the adjacent cutting film 54 and the intermediate reproduction film 52 (both having the perpendicular magnetization state). Becomes At this time, the magnetization of the reproduction auxiliary film 53 follows the magnetization of the cutting film 54 and has the same direction as the magnetization of the memory film 54. Note that this medium temperature region 7
The transfer of the magnetization of the memory film 55 in 1E is sufficiently performed because the thickness D53 (10 nm) of the auxiliary reproduction film 53 is smaller than the thickness D52 (40 nm) of the intermediate reproduction film 52.

The magnetization of the reproduction intermediate film 52 adjacent to the auxiliary reproduction film 53 also has the same direction as the magnetization of the memory film 55 due to the exchange coupling force from the auxiliary reproduction film 53. Further, the magnetization of the reproducing film 51 adjacent to the reproducing intermediate film 52 has the same direction as the magnetization of the memory film 55 due to the exchange coupling force from the reproducing intermediate film 52. At this time, the reproducing magnetic field Hr is also applied to the intermediate temperature region 71E. However, in determining the direction of magnetization of the reproducing film 51 in the intermediate temperature region 71E, the reproducing magnetic field Hr is applied to the reproducing intermediate film 52 more than the magnetostatic coupling force of the reproducing magnetic field Hr. Exchange coupling force greatly contributes.

As described above, in the three regions 71D, 71E and 71F in the beam spot 71A, the reproduction intermediate film 5
2. The auxiliary reproduction film 53 is in a different state depending on the temperature, and only in the middle temperature region 71E, the magnetization of the memory film 55 is changed to the auxiliary reproduction film 53 → the intermediate reproduction film 52 → the reproduction film 51.
Are transferred in order. In the low temperature region 71D, a mask (low temperature mask) is formed by the stable in-plane magnetization state of the reproduction intermediate film 52 and the reproduction auxiliary film 53 described above.
Further, in the high temperature region 71F, the above-mentioned reproduced intermediate film 52,
A mask (high-temperature mask) is formed according to the magnetization disappearance state of the reproduction auxiliary film 53. And these low temperature regions 71
D, in the high temperature region 71F, as described above,
Are uniformly aligned in the erasing direction.

The size of the medium temperature region 71E where the transfer of the magnetization of the memory film 55 to the reproducing film 51 is performed is such that only one small recording mark formed at a constant interval (0.3 μm) in the memory film 55 is formed. Can enter. Specifically, the size of the intermediate temperature region 71E is determined by the composition of the intermediate reproduction film 52 (Gd30Fe70), the composition of the auxiliary reproduction film 53 (Gd35Fe62Co3), and the composition of the cut film 54 (Tb2
0Fe80), the reproduction power (2 mW), and the rotational speed of the disc (9 m / sec).

For this reason, of the plurality of recording marks formed on the memory film 55 at fixed narrow intervals, only one of the recording marks is used in the medium temperature region 71E in the reproduction auxiliary film 53.
(Transfer mark 53A) → reproduction intermediate film 52 (transfer mark 5
2A) → the reproduction film 51 (transfer mark 51A). As described above, beam spot 71A
, One transfer mark 51 is provided only in the medium temperature region 71E.
A (the TM sublattice magnetization is in the recording direction) is formed, and in the low temperature region 71D and the high temperature region 71F, the TM sublattice magnetization is uniformly aligned in the erasing direction.
By detecting the component (reflected light) of the reproduction light 71 reflected by A, only one of the plurality of recording marks formed on the memory film 55 can be accurately (for example, so as not to cause crosstalk). Can be played.

As described above, according to the rewritable magneto-optical disk 50 of the second embodiment, between the memory film 55 and the reproducing film 51, the reproducing intermediate film 52 (in-plane magnetic film, predetermined temperature Tx52) And the auxiliary reproduction film 53 (in-plane magnetized film, predetermined temperature Tx53> predetermined temperature Tx52), the low-temperature mask in the low-temperature region 71D is reduced by a small reproduction magnetic field Hr.
Thus, a reliable mask can be obtained. As a result, the information of the memory film 55 can be masked not only in the low-temperature region 71D but also in the high-temperature region 71F, and the information of the memory film 55 is transferred only in the middle-temperature region 71E, so that the double mask reproduction becomes more practical.

Further, according to the rewritable magneto-optical disk 50 of the second embodiment, the memory film 55 and the reproduction auxiliary film 5
3, the cutting film 54 (perpendicular magnetization film, Curie temperature T
Since c54 (Tc53, Tc52>Tc54> Tx52) is formed, it is possible to secure a wide high-temperature region 71F in which high-density information of the memory film 55 can be masked even if the power of the reproduction light 41 is small.

Therefore, according to the rewritable magneto-optical disk 50 of the second embodiment, information (a plurality of recording marks) recorded on the memory film 55 at high density can be accurately reproduced one by one. When the carrier-to-noise intensity ratio (CN ratio) of the rewritable magneto-optical disk 50 was actually measured, it was found that a good CN ratio of 45 dB or more was obtained.

Incidentally, the magneto-optical disk 50 of the second embodiment
In the above, an example in which the thickness D53 of the reproduction auxiliary film 53 is set to 10 nm has been described.
As in the case of the auxiliary reproduction film 13 of the first embodiment, it can be set to an arbitrary value within a range thicker than 0.2 nm and thinner than 30 nm. Also, the magneto-optical disk 5 of the second embodiment
0, an example was described in which the sum of the film thickness D52 of the reproduction intermediate film 52 and the film thickness D53 of the reproduction auxiliary film 53 was 50 nm. However, this sum was larger than 40 nm as in the first embodiment. If desired, it can be set to any value.

Further, the magneto-optical disk 50 of the second embodiment
In the above, an example in which a small reproduction magnetic field Hr is applied has been described. However, in the low temperature region 71D, the influence of the exchange coupling force from the reproduction intermediate film 52 and the reproduction auxiliary film 53 both in a stable in-plane magnetization state is considered. As a result, if the magnetization of the reproducing film 51 becomes a stable in-plane magnetization state, the reproducing magnetic field H
It is not necessary to apply r, and the size of the device can be further reduced because the magnetic field generation source does not need to be built in.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIG. Note that this third
The embodiment corresponds to claims 1 to 8. The magneto-optical disk 80 of the third embodiment is one in which the present invention is applied to a magneto-optical disk of a light modulation overwrite recording system. That is, the magneto-optical disk 80 is the same as the reproducing film 5 in the rewritable magneto-optical disk 50 of the second embodiment.
1, a reproduction film 81, a reproduction intermediate film 82, a reproduction auxiliary film 83 corresponding to the reproduction intermediate film 52, the reproduction auxiliary film 53, and the cut film 54;
The cutting film 84 is formed on a magneto-optical disk of a light modulation overwrite recording system to enable high-density information reproduction.

First, the magneto-optical disk 80 of the third embodiment
Will be described. The magneto-optical disk 80 according to the third embodiment includes a substrate 91 from above to below in FIG.
A protective film 92, a reproducing film 81, a reproducing intermediate film 82, a reproducing auxiliary film 83, a cutting film 84, a memory film 85, an intermediate film 86,
It has a structure in which a recording film 87, a switching film 88, an initialization film 89, a protection film 93, a metal film 94, and a resin protection film 95 are sequentially formed.

In the magneto-optical disk 80 of the third embodiment, of the films 81 to 89 and 92 to 95 described above, the reproduction film 81, the reproduction intermediate film 82, the reproduction auxiliary film 83, and the cutting film 84
When reproducing information, the magneto-optical disk 5 of the second embodiment
The same operations as those of the reproduction film 51, the reproduction intermediate film 52, the reproduction auxiliary film 53, and the cutting film 54 are performed. Here, each of the films 81 to 89, 92 to 92 to configure the magneto-optical disk 80 of the third embodiment.
The composition, film thickness, and function of 95 will be described. In addition,
These films 81 to 88 and 92 to 95 are also formed by a well-known sputtering method.

The reproducing film 81 is composed of Gd which is a rare earth metal,
This is a perpendicular magnetization film composed of transition metals Fe and Co. The composition of the reproducing film 81 is Gd25Fe60Co15, and the thickness D81 thereof is 30 nm.

The reproduced film 81 having such a composition and thickness is as follows.
Is designed so that its magnetization is maintained in a perpendicular magnetization state even when its temperature is increased by irradiation of reproduction light. Further, since the reproducing film 81 has the above-described composition, its Curie temperature Tc81 is at least the Curie temperature Tc82 (230 ° C.) of the reproducing intermediate film 82 described later and the reproducing auxiliary film 8.
3, which is higher than the Curie temperature Tc83 (230 ° C.). Also, the Curie temperature Tc81 is higher than the highest temperature (corresponding to a temperature T2 described later) that is raised by the irradiation of the reproduction light, similarly to a Curie temperature Tc85 of the memory film 85 described later.

The reproducing intermediate film 82 is composed of Gd which is a rare earth metal and Fe which is a transition metal. The composition of the reproducing intermediate film 82 is Gd30Fe70, and the RE sublattice magnetization is dominant. Further, the thickness D82 of the reproduction intermediate film 82
Is 40 nm. The reproducing intermediate film 82 having such a composition and film thickness is an in-plane magnetic film in which the magnetization is oriented in-plane (horizontal direction in FIG. 9) at room temperature Tr.

Since the reproducing intermediate film 82 has the above composition, its magnetization changes from an in-plane magnetization state to a perpendicular magnetization state at a predetermined temperature Tx82 higher than the room temperature Tr. The predetermined temperature Tx82 is around 130 ° C. (for example, ° C ~ C). Further, the reproduced intermediate film 8
2 has a Curie temperature Tc82 of 2 due to the above composition.
It will be about 30 ° C. This Curie temperature Tc82 (230
° C) is the Curie temperature Tc81 of the reproduction film 81 described above,
It is lower than any of the Curie temperatures Tc85 of the memory film 85.

The auxiliary reproduction film 83 is composed of Gd which is a rare earth metal and Fe and Co which are transition metals.
The composition of the reproduction auxiliary film 83 is Gd35Fe62Co3, and the RE sublattice magnetization is dominant similarly to the reproduction intermediate film 82 described above. The thickness D83 of the reproduction assisting film 83 is 10
nm. The reproduction assisting film 8 having such composition and film thickness
Reference numeral 3 denotes an in-plane magnetized film in which the magnetization is oriented in-plane, similar to the reproducing intermediate film 82, at room temperature Tr.

Since the auxiliary reproduction film 83 has the above-mentioned composition, its magnetization changes from the in-plane magnetization state to the perpendicular magnetization state at the predetermined temperature Tx83 higher than the room temperature Tr. Here, the ratio of the rare earth metal (Gd) (35 at%) in the reproduction auxiliary film 83 is such that the rare earth metal
Since the composition is higher than the ratio (Gd) (30 atomic%), the predetermined temperature Tx83 of the reproduction auxiliary film 83 is higher than the predetermined temperature Tx82 (130 ° C.) of the reproduction intermediate film 82. Therefore, the auxiliary reproduction film 83 can maintain the magnetization in the in-plane magnetization state up to a higher temperature than the intermediate reproduction film 82.

The Curie temperature Tc83 of the auxiliary reproduction film 83 is about 230 ° C. due to the above composition. This Curie temperature Tc83 (230 ° C.) is substantially the same as the Curie temperature Tc82 of the reproduced intermediate film 82 described above. The Curie temperature Tc83 is lower than the Curie temperature Tc81 of the reproduced film 81 and the Curie temperature Tc85 of the memory film 85, similarly to the reproduced intermediate film 82.

The cutting film 84 is made of T which is a rare earth metal.
b and a perpendicular magnetic film composed of Fe as a transition metal. The composition of the cut film 84 is Tb20Fe80,
The thickness D85 is 20 nm. The cut film 84 having such a composition and thickness has a Curie temperature Tc84 of 14
It is about 0 ° C. Curie temperature Tc84 (140 ° C)
Is the Curie temperature Tc83 (2
30 ° C.), the Curie temperature Tc 82 (23
0 ° C). The Curie temperature Tc84 (1
40 ° C.) is the predetermined temperature Tx82 of the reproduction intermediate film 82 described above.
(130 ° C).

The memory film 85 is a perpendicular magnetization film composed of Tb, which is a rare earth metal, and Fe, Co, which are transition metals. The composition of the memory film 85 is as follows:
Tb18Fe74Co8, and its thickness D85 is 35 nm.
It is.

As in the memory film 14 of the first embodiment, the memory film 85 has the RE sublattice magnetization downward and TM
Information is recorded in a state where the sub-lattice magnetization is upward and a state where the RE sub-lattice magnetization is upward and the TM sub-lattice magnetization is downward. The memory film 85 has a compensation temperature Th85.
Is lower than the room temperature Tr. Then, as the temperature of the memory film 85 rises due to the irradiation of the reproduction light, the balance between the RE sub-lattice magnetization and the TM sub-lattice magnetization is lost, and the entire magnetization increases while maintaining the perpendicular magnetization state. It has become.

Since the memory film 85 has the above composition, the Curie temperature Tc84 of the memory film 85 will be described later.
Is lower than the Curie temperature Tc86 (230 ° C.) of the reproduction intermediate film 82 and the Curie temperature Tc83 (230 ° C.) of the reproduction auxiliary film 83 described above. Further, the coercive force of the memory film 85 at room temperature Tr is higher than that of the other magnetic films other than the initialization film 89 described later, so that the recorded information is stably held.

The intermediate film 86 is made of G which is a rare earth metal.
In the case where there is no magnetic material (particularly, a perpendicular magnetization film) formed of d and transition metals Fe and Co, and is formed adjacently, it is an in-plane magnetization film at room temperature Tr. Also, this intermediate film 8
The composition of No. 6 is Gd32 Fe64 Co4, and its film thickness D86
Is 10 nm. Since the intermediate film 95 has the above composition, it has almost no coercive force.

The recording film 87 is a perpendicular magnetization film composed of dysprosium (Dy), which is a rare earth metal, and Fe, Co, which are transition metals. The composition of this recording film 87 is Dy26Fe48Co26, and its film thickness D87 is 20
nm. This recording film 87 has its compensation temperature Th86.
Is a film between the room temperature Tr and the Curie temperature Tc86.

The switching film 88 is a perpendicular magnetization film composed of Tb, which is a rare earth metal, and Fe, Co, which are transition metals. The composition of the switching film 88 is Tb17Fe77Co6, and its film thickness D88 is 12
nm. The Curie temperature Tc87 of the switching film 88 is the same as the Curie temperature Tc of the recording film 87 described above.
86 and a Curie temperature Tc88 of the initialization film 89 described later.

The initialization film 89 is a perpendicular magnetization film composed of Tb, which is a rare earth metal, and Fe, Co, which are transition metals. The composition of the initialization film 89 is Tb18Fe
16Co66, and its film thickness D89 is 20 nm. The initialization film 89 has a Curie temperature Tc88 higher than the above-described Curie temperature Tc86 of the recording film 87, and has a high coercive force.

The protective films 92 and 93 for protecting the magnetic films 81 to 89 are made of silicon nitride.
The thickness D92 is 70 nm, and the thickness D93 is 30 nm.
The metal film 94 is a film for adjusting the recording sensitivity, and is made of an aluminum thin film having a thickness D94 of 30 nm. Further, the resin protective film 95 is formed of the above-described respective films 8 deposited on the substrate 91.
It is a film that entirely protects 1 to 89 and 92 to 94. The substrate 91 is a polycarbonate substrate (90 mm in diameter) in which guide grooves are formed in a spiral shape.

The overwrite recording of information on the memory film 85 of the magneto-optical disk 80 of the optical modulation overwrite recording system configured as described above is performed as follows. First, in overwriting recording of information, the magneto-optical disk 80 is continuously irradiated with recording light (wavelength 680 nm) from a recording / reproducing device (not shown). Information is written by modulating the recording power at this time (high level / low level). In the overwrite recording, a recording magnetic field (recording direction) having a constant magnitude is continuously applied to the beam spot of the recording light. The direction of the recording magnetic field is opposite to the direction of magnetization (erasing direction) of the initialization film 89. During overwrite recording, the magneto-optical disk 80 is rotated at a constant linear speed (for example, 9 m / sec) by a motor.

When the recording power is at a high level, at least a part (heating area) in the beam spot has at least the recording film 8.
7, the magnetization of the recording film 87, the memory film 85, and the switching film 88 temporarily disappears. Thereafter, when the above-mentioned heated area deviates from the beam spot and its temperature gradually decreases toward room temperature Tr, the magnetization of the recording film 87 is recovered, and the direction of the magnetization follows the recording magnetic field ( Recording direction). This recording film 87
Of the memory film 85 whose magnetization is subsequently recovered
Is transferred in the process of lowering the temperature. Thus, the information once recorded on the recording film 87 by the recording magnetic field is recorded and held on the memory film 85.

After the information is transferred from the recording film 87 to the memory film 85, if the temperature further decreases, the initialization film 89
By this operation, the direction of magnetization of the recording film 87 is aligned in one direction, and the recording film 87 is initialized. Note that an intermediate film 86 is provided between the recording film 87 and the memory film 85, and when the initialization of the recording film 87 is performed by the function of the initialization film 89, the gap between the recording film 87 and the memory film 85 is formed. The exchange coupling force is weakened, and the memory film 85
7, so that it is not initialized.

A switching film 88 is provided between the initialization film 89 and the recording film 87. When information is recorded on the recording film 87 by a recording magnetic field, the above-mentioned initialization film 8 is used.
9 prevents transmission of the exchange coupling force to the recording film 87. By irradiating high-level recording light in this manner, one recording mark (the magnetization direction is the recording direction) can be overwritten in a region (high-temperature region) smaller than the beam spot of the memory film 85.

On the other hand, when the recording power is low, the temperature of a part (high temperature region) in the beam spot becomes higher than the Curie temperature Tc85 of the memory film 85, as in the case of the high level. It does not reach the Curie temperature Tc87. Therefore, the magnetization of the memory film 85 temporarily disappears, but the magnetization of the recording film 87 remains initialized.

Thereafter, the temperature of the high temperature region is set to the room temperature Tr.
As the temperature gradually decreases, the magnetization of the memory film 85 recovers, and the direction of the magnetization is aligned in one direction and follows the magnetization of the recording film 87 (erasing direction). And room temperature T
At r, the magnetization of the memory film 85 is maintained while following the initialized recording film 87. By irradiating low-level recording light in this manner, a recording mark can be erased in a region (high-temperature region) smaller than the beam spot of the memory film 85.

Therefore, for the magneto-optical disk 80,
The recording power is modulated according to the information to be recorded (high level /
(Low level), recording marks smaller than the beam spot can be overwritten on the memory film 85 one after another. Here, the interval between recording marks formed by overwrite recording is determined by the modulation interval of recording light and the rotation speed of the magneto-optical disk 10, and the interval is about 0.3 μm.

The memory film 85 on which information is recorded and held in this way is irradiated with reproduction light as described below, so that high-density information can be reproduced. In reproducing information, the magneto-optical disk 80 is continuously irradiated with reproduction light having a constant power (having a wavelength of 680 nm).
State of linearly polarized light). In this case, the power of the reproduction light is set to a value smaller than the power of the reproduction light 41 irradiated at the time of reproducing the information on the magneto-optical disk 10 of the first embodiment, as in the case of the second embodiment. (For example, 2 mW) In reproducing information, a reproducing magnetic field of a constant magnitude is continuously applied to the beam spot of the reproducing light (an erasing direction opposite to the direction of the recording magnetic field). The magnitude of the reproducing magnetic field is smaller than the value of the reproducing magnetic field necessary for the conventional double mask reproduction (for example, 100 (Oe)), as described later. Therefore, the magnetic coil of the recording / reproducing apparatus can be configured with a small number of turns,
Also, the power supply can be reduced.

Further, when reproducing information, the magneto-optical disk 80 is rotated at the same linear speed as that during the above-mentioned overwrite recording (for example, 9 m / sec). At the time of reproduction, when the reproduction light is actually irradiated, the magneto-optical disk 8
As in the case of the magneto-optical disk 10 according to the first embodiment, a high-temperature area (temperature T2) in the beam spot on the zero point from the front to the rear in the moving direction at a certain temperature.
Medium temperature region (temperature T3), low temperature region (temperature T4) 3
Can be divided into two areas.

In the third embodiment, the reproduction light (2
mW), the temperature T2 becomes higher than 140 ° C. (Curie temperature Tc84 of the cut film 84) in the high temperature region. In the middle temperature range, the temperature is lower than 140 ° C.
The temperature T3 is higher than the temperature C (the predetermined temperature Tx82 of the reproducing intermediate film 82). Further, in the low temperature region, the temperature T4 is lower than 130 ° C.

As described above, in each of the beam spots divided into three regions having different temperatures, each of the magnetic films 81 to 8 is formed.
The magnetizations of Nos. 5 are in the states described below. The magnetization of the memory film 85 is stably maintained as recorded in any region in the beam spot. This is because the temperature in the beam spot (the highest temperature is the temperature T2 in the high-temperature region, and the lowest temperature is the temperature T4 in the low-temperature region) is the Curie temperature Tc85 (2
60 ° C.), the magnetization does not disappear, and
This is because the coercive force is sufficiently high to hold information.

The magnetization of the reproducing film 81 is maintained in the perpendicular magnetization state in any region within the beam spot. This is because the temperature in the beam spot (temperature T
2 and higher than the temperature T4) but lower than the Curie temperature Tc81 of the reproducing film 81. On the other hand, the magnetization of the reproduction intermediate film 82, the magnetization of the reproduction auxiliary film 83, and the magnetization of the cutting film 84 are in a low temperature region (temperature T) in the beam spot.
4) Each of the middle temperature region (temperature T3) and the low temperature region (temperature T2) is in a different state according to the temperature.

Here, the state of magnetization of the reproduction intermediate film 82, the state of magnetization of the reproduction auxiliary film 83, the state of magnetization of the cutting film 84, and the operation of reproducing information will be described for each region in the beam spot. In the low temperature region, the temperature T4
However, since it is lower than the Curie temperature Tc84 (140 ° C.) of the cut film 84, the magnetization of the cut film 84 is maintained in a perpendicular magnetization state without disappearing. At this time, the cutting film 8
The magnetization of No. 4 has the same direction following the magnetization of the memory film 85 due to the influence of the exchange coupling force from the memory film 85 formed adjacently.

In the low temperature region, the temperature T4 is set to a predetermined temperature Tx82 (130 ° C.) at which the reproducing intermediate film 82 changes from the in-plane magnetization state to the perpendicular magnetization state.
3 is lower than a predetermined temperature Tx83 (Tx83> Tx82) at which the in-plane magnetization state changes to the perpendicular magnetization state. Therefore, the reproduction auxiliary film 83 has a strong tendency that its magnetization becomes an in-plane magnetization state. At this time, the magnetization of the reproduction assisting film 83 receives exchange coupling force from the adjacent cut film 84, but has a sufficiently strong tendency to be in the in-plane magnetization state, and does not change to the perpendicular magnetization state. The state is maintained.

On the other hand, the reproduction intermediate film 82 has a predetermined temperature Tx at which the in-plane magnetization state changes to the perpendicular magnetization state as described above.
Since the temperature 82 is lower than the predetermined temperature Tx83 of the auxiliary reproduction film 83, the magnetization thereof is also relatively weak in the in-plane magnetization state. When the in-plane magnetization state is relatively weak as described above, the reproducing intermediate film 82
If there is no adjacent magnetic film, the magnetization is stably maintained in the in-plane magnetization state, but if the adjacent magnetic film is formed, the influence of the exchange coupling force from the magnetic film causes
The in-plane magnetization state of the magnetization tends to be unstable. At this time, when the adjacent magnetic film is the in-plane magnetic film, the magnetization of the reproducing intermediate film 82 is maintained in the in-plane magnetization state, but when the perpendicular magnetic film is adjacent, the magnetization is in the perpendicular magnetization state. And easily.

However, in the magneto-optical disk 80 of the third embodiment, the auxiliary reproduction film 83 is adjacent to the intermediate reproduction film 82.
(The magnetization tends to be in the in-plane magnetization state), the magnetization of the reproduction intermediate film 82 is affected by the exchange coupling force from the auxiliary reproduction film 83, and the in-plane magnetization state becomes stable. (Fig. 7). As described above, since the reproduction intermediate film 82 and the reproduction auxiliary film 83 both have a stable in-plane magnetization state in the low temperature region, the exchange coupling force from the memory film 85 does not act on the reproduction film 81. As a result, in the low temperature region, a mask is reliably formed, and the magnetization of the memory film 85 is not transferred to the reproduction film 81.

If the in-plane magnetization state of the reproducing intermediate film 82 is relatively weak, the perpendicular magnetization state of the reproducing film 81 tends to be unstable. A large reproducing magnetic field (500 (Oe)) had to be applied to align the perpendicular magnetization state of the film 81 in the erasing direction. However, as described above, both the reproducing intermediate film 82 and the reproducing auxiliary film 83 have stable surfaces. If it is in the internal magnetization state, the reproducing magnetic field Hr applied to the reproducing film 81 in the low temperature region
Is small (100 (Oe)), the TM
The sublattice magnetization can be easily aligned in the erasing direction (downward in FIG. 9).

In the high temperature region, the temperature T2 is 14
Since the temperature is higher than 0 ° C. (Curie temperature Tc84 of the cut film 84), the magnetization of the cut film 84 has disappeared. Therefore, in the high temperature region, the exchange coupling force between the memory film 85 and the reproduction film 81 is cut off. Further, in this high temperature region, since the power of the reproduction light is small, 230 ° C. (the Curie temperature Tc 82 of the reproduction intermediate film 82 and the Curie temperature T
It can be considered that the temperature is higher than c83), and that the temperature is higher than c83).

In a part of the high temperature region, the temperature is higher than 230 ° C. (the Curie temperature Tc82 of the reproduction intermediate film 82 and the Curie temperature Tc83 of the reproduction auxiliary film 83). Both the magnetizations of the reproduction auxiliary film 83 have disappeared. Therefore, in this part, the magnetostatic coupling force between the memory film 85 and the reproducing film 81 is also cut. At this time, the memory film 85 and the reproducing film 81
Is 70 nm, which is a value such that the magnetostatic coupling force does not act.

In addition, except for the above-mentioned part of the high-temperature region,
Since the temperature is lower than 230 ° C. and higher than 140 ° C., the magnetizations of the reproduction intermediate film 82 and the reproduction auxiliary film 83 are both changed from the in-plane magnetization state to the perpendicular magnetization state. However, other than this part, the influence of the magnetostatic coupling force from the memory film 85 to the reproduction assisting film 83 does not act. As described above, in the third embodiment, since the power of the reproduction light is small, the reproduction intermediate film 82 and the reproduction auxiliary film 8 are located in the high temperature region.
3 and the reproduction intermediate film 82,
A portion where the magnetization of the reproduction auxiliary film 83 is in the perpendicular magnetization state is mixed. However, since the magnetization of the cutting film 84 formed between the memory film 85 and the reproduction assisting film 83 has disappeared, the magnetization of the memory film 85 can be
It is not transferred to the reproduction film 81.

At this time, the reproducing film 81 in the high-temperature region has a perpendicular magnetization state, but its TM sublattice magnetization becomes uniform under the influence of the continuously applied reproducing magnetic field Hr. The state is aligned in the erasing direction (downward in FIG. 9). In the middle temperature region, the temperature T3 is lower than the Curie temperature Tc84 (140 ° C.) of the cut film 84, so that the magnetization of the cut film 84 is maintained in the perpendicular magnetization state without disappearing. At this time, the magnetization of the cut film 84 has the same direction following the magnetization of the memory film 85 due to the influence of the exchange coupling force from the memory film 85 formed adjacently.

In the medium temperature range, the temperature T3 is 1
Since the temperature is higher than 30 ° C. (the predetermined temperature Tx82 of the reproducing intermediate film 82), the magnetization of the reproducing intermediate film 82 is in an in-plane magnetization state (FIG. 9).
The state changes from the middle and the horizontal directions) to the perpendicular magnetization state (the vertical direction in FIG. 9). Further, since the temperature T3 in the medium temperature region is lower than the Curie temperature Tc83 (230 ° C.) of the auxiliary reproduction film 83, the magnetization of the auxiliary reproduction film 83 in the intermediate temperature region has an in-plane magnetization state as in the low temperature region. It has become.

However, since the temperature in the medium temperature region (temperature T3) is higher than that in the low temperature region (temperature T4), the auxiliary reproduction film 83 in the medium temperature region has a higher temperature than that in the low temperature region. The tendency of the magnetization to become an in-plane magnetization state is weakened. Here, the auxiliary reproduction film 83 in the intermediate temperature region is maintained in an in-plane magnetization state if there is no adjacent magnetic material.
When the magnetic films are formed adjacent to each other, the in-plane magnetization state of the magnetization becomes unstable under the influence of the exchange coupling force from the magnetic films.

Therefore, in this middle temperature region, the magnetization of the reproduction auxiliary film 83 is changed to the adjacent cut film 84 and reproduction intermediate film 82.
(Both magnetizations are in a perpendicular magnetization state) and are in a perpendicular magnetization state under the influence of the exchange coupling force. At this time, the reproduction assisting film 83
The magnetization of the memory film 85 follows the magnetization of the cutting film 84.
It has the same direction as the magnetization of. In the transfer of the magnetization of the memory film 85 in the middle temperature region, the thickness D83 (10 nm) of the auxiliary reproduction film 83 is changed to the thickness D82 (40 nm) of the intermediate reproduction film 82.
nm), which is sufficient.

The magnetization of the intermediate reproduction film 82 adjacent to the auxiliary reproduction film 83 also has the same direction as the magnetization of the memory film 85 due to the exchange coupling force from the auxiliary reproduction film 83. Further, the magnetization of the reproducing film 81 adjacent to the reproducing intermediate film 82 has the same direction as the magnetization of the memory film 85 due to the exchange coupling force from the reproducing intermediate film 82. At this time, the reproducing magnetic field Hr is also applied to the intermediate temperature region. However, in determining the magnetization direction of the reproducing film 81 in the intermediate temperature region, the exchange of the reproducing magnetic field Hr from the reproducing intermediate film 82 is more difficult than the magnetostatic coupling force. The bonding force contributes more.

As described above, in the three regions within the beam spot, the reproducing intermediate film 82 and the reproducing auxiliary film 83 are in different states according to their temperatures.
The magnetization of the memory film 85 is transferred in the order of the auxiliary reproduction film 83 → the intermediate reproduction film 82 → the reproduction film 81. In the low temperature region, a mask (low temperature mask) is formed by the stable in-plane magnetization state of the reproduction intermediate film 82 and the reproduction auxiliary film 83 described above. In the high temperature region, the above-mentioned reproduced intermediate film 8 is formed.
2. A mask (high-temperature mask) is formed depending on the state of magnetization disappearance of the reproduction auxiliary film 83. In the low temperature region and the high temperature region, as described above, the TM
The sublattice magnetization is uniformly aligned in the erasing direction.

By the way, the size of the medium temperature region where the transfer of the magnetization of the memory film 85 to the reproducing film 81 is performed is such that only one small recording mark formed at a constant interval (0.3 μm) is formed in the memory film 85. Degree. More specifically, the size of the intermediate temperature region is determined by the composition of the intermediate reproduction film 82 (Gd30Fe70) and the composition of the auxiliary reproduction film 83 (Gd35F
e62Co3), the composition of the cut film 84 (Tb20Fe80), the reproducing power (2 mW), and the disk rotation speed (9 mW).
/ Sec).

For this reason, among a plurality of recording marks formed at a fixed narrow interval on the memory film 85, only one of the recording marks is formed in the middle temperature region in the order of the reproduction auxiliary film 83 → the reproduction intermediate film 82 → the reproduction film 81. It will be transferred in order.
As described above, in the beam spot, one transfer mark 81A (the TM sublattice magnetization is in the recording direction) is formed only in the medium temperature region, and the TM sublattice magnetization is uniformly aligned in the erasing direction in the low temperature region and the high temperature region. Therefore, by detecting the component (reflected light) of the reproduction light reflected by the beam spot, only one of the plurality of recording marks formed on the memory film 85 is accurately detected (for example, crosstalk occurs). Can be played).

As described above, according to the magneto-optical disk 80 of the light modulation overwrite recording system of the third embodiment, the intermediate reproduction film 82 (the in-plane magnetization film) is provided between the memory film 85 and the reproduction film 81. , A predetermined temperature Tx82) and the reproduction assisting film 8
Since 3 (in-plane magnetized film, predetermined temperature Tx83> predetermined temperature Tx82) is formed, a low-temperature mask in a low-temperature region can be a reliable mask with a small reproducing magnetic field Hr. As a result, the information of the memory film 85 can be masked not only in the low-temperature region but also in the high-temperature region, and the information of the memory film 85 is transferred only in the medium-temperature region, so that the double mask reproduction becomes more practical.

Further, according to the magneto-optical disk 80 of the light modulation overwrite recording system of the third embodiment, the cutting film 84 (perpendicular magnetization film, Curie temperature Tc84, However, Tc83, Tc82> Tc
84> Tx82), it is possible to secure a wide high-temperature region where the high-density information of the memory film 85 can be masked even if the power of the reproduction light is small.

Therefore, according to the magneto-optical disk 80 of the optical modulation overwrite recording method of the third embodiment, information (a plurality of recording marks) recorded on the memory film 85 at high density is accurately reproduced one by one. be able to. Further, according to the third embodiment, since information is reproduced by using a low-power reproducing light, the information is generally reproduced as compared with the rewritable magneto-optical disks 10 and 50 of the first and second embodiments. Even with the magneto-optical disk 80 of the light modulation overwrite recording method in which the Curie temperature Tc85 of the memory film 85 is low, double mask reproduction becomes more practical.

The actual measurement of the carrier-to-noise ratio (CN ratio) of the magneto-optical disk 80 of the optical modulation overwrite recording method revealed that a good CN ratio of 45 dB or more was obtained. In the magneto-optical disk 80 of the third embodiment, the example in which the thickness D83 of the reproduction auxiliary film 83 is set to 10 nm has been described. However, the thickness D83 of the reproduction auxiliary film 83 is the same as that of the second embodiment. As with the auxiliary film 13, it can be set to any value within a range greater than 0.2 nm and less than 30 nm.

The magneto-optical disk 80 of the third embodiment
In the above, an example in which the sum of the thickness D82 of the reproduction intermediate film 82 and the thickness D83 of the reproduction auxiliary film 83 is set to 80 nm has been described.
This sum can be set to any value as long as it is thicker than 40 nm, as in the second embodiment.

The magneto-optical disk 80 of the third embodiment
In the above description, an example in which a small reproducing magnetic field Hr is applied has been described. However, in the low temperature region, the influence of the exchange coupling force from the reproducing intermediate film 82 and the reproducing auxiliary film 83 both of which are in a stable in-plane magnetization state. If the magnetization of the reproducing film 81 is also stably maintained in the in-plane magnetization state, the reproducing magnetic field Hr does not need to be applied, and the device can be downsized because the magnetic field generating source does not need to be built in. Can be

[0184]

As described above, claims 1 to 8 are described.
According to the magneto-optical recording medium described in (1), even in the low-temperature region in the beam spot of the reproduction light, the reproduction intermediate film, whose in-plane magnetization state tends to be unstable, also reproduces the stable in-plane magnetization state adjacent thereto. Because the in-plane magnetization state can be stabilized by the influence of the auxiliary film, even if the external magnetic field applied to the beam spot during reproduction is small, the memory film can be formed not only in the high-temperature region but also in the low-temperature region in the beam spot. The recorded information can be surely masked, and the information recorded on the memory film can be reproduced only in a small medium temperature area. Therefore, the information can be accurately reproduced on a magneto-optical recording medium of which the density has been increased by writing the information finely using a pen tip recording method or the like.

[Brief description of the drawings]

FIG. 1 is a rewritable magneto-optical disk 10 according to a first embodiment.
It is sectional drawing which shows a structure of.

FIG. 2 is a memory film 1 of a rewritable magneto-optical disk 10
FIG. 4 is a cross-sectional view illustrating an operation of recording information on No. 4.

FIG. 3 is a memory film 1 of a rewritable magneto-optical disk 10;
FIG. 4 is a diagram for explaining an operation of recording information in No. 4;

FIG. 4 is a memory film 1 of a rewritable magneto-optical disk 10
FIG. 4 is a cross-sectional view illustrating a reproducing operation of information recorded in No. 4;

FIG. 5 is a memory film 1 of a rewritable magneto-optical disk 10
FIG. 4 is a diagram for explaining a reproduction operation of information recorded in No. 4;

FIG. 6 shows a rewritable magneto-optical disk 50 according to a second embodiment.
It is sectional drawing which shows a structure of.

FIG. 7 shows a memory film 5 of a rewritable magneto-optical disk 50.
FIG. 9 is a cross-sectional view illustrating a reproducing operation of information recorded in No. 5.

FIG. 8 is a memory film 5 of a rewritable magneto-optical disk 50;
FIG. 9 is a diagram for explaining an operation of reproducing information recorded in No. 5;

FIG. 9 is a cross-sectional view illustrating a configuration of a magneto-optical disk 80 according to a third embodiment.

FIG. 10 shows a memory film 1 of a conventional magneto-optical disk 100.
FIG. 14 is a cross-sectional view for explaining a reproduction operation of information recorded in No. 13.

FIG. 11 shows a memory film 1 of a conventional magneto-optical disk 100.
FIG. 14 is a diagram for explaining an operation of reproducing information recorded in the information recording device 13;

[Explanation of symbols]

10, 50, 80, 100 Magneto-optical disk 11, 51, 81, 111 Reproduction film 12, 52, 82, 112 Reproduction intermediate film 13, 53, 83 Reproduction auxiliary film 14, 55, 85, 113 Memory film 54, 84 Cutting Films 21, 61, 91, 121 Substrates 31A, 41A, 71A Beam spots 11A, 12A, 13A, 51A, 52A, 53A, 5
4A Transfer mark 14A Record mark 14B Heating area 41F, 71F High temperature area 41E, 71E Medium temperature area 41D, 71D Low temperature area 86 Intermediate film 87 Recording film 88 Switching film 89 Initialization film 94 Metal layer 95 Resin protective layer

Claims (8)

[Claims] 1. A reproducing film comprising a perpendicular magnetic film, a reproducing intermediate film comprising an in-plane magnetic film, a reproduction auxiliary film comprising an in-plane magnetic film, and a memory film comprising a perpendicular magnetic film are provided on a substrate. The reproduction intermediate film is a film whose Curie temperature is lower than any of the Curie temperature of the reproduction film and the Curie temperature of the memory film. The reproduction auxiliary film has a Curie temperature of the reproduction film. The temperature at which the Curie temperature of the film is lower than the Curie temperature of the memory film and the temperature at which the in-plane magnetization state changes to the perpendicular magnetization state changes the in-plane magnetization state of the reproducing intermediate film to the perpendicular magnetization state. A magneto-optical recording medium characterized by a film having a higher temperature. 2. The magneto-optical recording medium according to claim 1, wherein the intermediate reproduction film and the auxiliary reproduction film are made of a rare earth metal and a transition metal, and the sub-lattice magnetization of the rare earth metal is dominant. The magneto-optical recording medium according to claim 1, wherein a ratio of the rare earth metal in the auxiliary reproduction film is higher than a ratio of the rare earth metal in the intermediate reproduction film. 3. The magneto-optical recording medium according to claim 1, wherein the thickness of the auxiliary reproduction film is greater than 0.2 nm and 30 n.
a magneto-optical recording medium characterized by being thinner than m. 4. The magneto-optical recording medium according to claim 1, wherein the sum of the thickness of the reproduction intermediate film and the thickness of the reproduction auxiliary film is greater than 40 nm. A magneto-optical recording medium characterized by the above-mentioned. 5. The magneto-optical recording medium according to claim 1, wherein a Curie temperature of the auxiliary reproduction film is equal to a Curie temperature of the intermediate reproduction film. Magneto-optical recording medium. 6. The magneto-optical recording medium according to claim 1, wherein a cutting film made of a perpendicular magnetization film is formed between the memory film and the reproduction auxiliary film. The Curie temperature of the cut film is lower than any of the Curie temperature of the auxiliary reproduction film and the Curie temperature of the intermediate reproduction film, and is higher than the temperature at which the in-plane magnetization state of the intermediate reproduction film changes to the perpendicular magnetization state. Magneto-optical recording medium characterized in that it also has a high magnetic recording medium. 7. The magneto-optical recording medium according to claim 1, wherein a recording film made of a perpendicular magnetic film and a switching film made of a perpendicular magnetic film are provided on the opposite side of the memory film from the substrate. A film and an initialization film made of a perpendicular magnetization film are sequentially formed, the Curie temperature of the recording film is higher than the Curie temperature of the memory film, and the Curie temperature of the switching film is at least the Curie temperature of the memory film. Wherein the Curie temperature of the initialization film is higher than the Curie temperature of the recording film. 8. The magneto-optical recording medium according to claim 7, wherein an intermediate film made of an in-plane magnetized film is formed between the memory film and the recording film. Medium.