JPH10326441A - Magneto-optical recording medium and its reproduction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reproduce micromagnetic domains smaller than the reproduction spot of a magneto-optical recording medium independently and with amplified regenerative signals. SOLUTION: This medium has a dielectric layer, GdFeCo reproducing layer, nonmagnetic layer and TbFeCo recording layer on a substrate. At the time of reproduction, a DC magnetic field Hex is impressed in the recording direction to modulate reproducing light to a low power and a high power in synchronization with a reproduction clock. The medium is irradiated with this light. The reproducing layer is a magnetic film changed from intra-surface magnetization to perpendicular magnetization at a critical temp. Tcr, has a compensation temp. Tcomp between room temp. and Curie temp. Tc and satisfy Troom<Tcr<Tcomp<Tco<Tc in a relation with the Curie temp. Tc of the recording layer. If the transfer magnetic field of the recording layer and the coercive force of the reproducing layer have the magnitude relation shown in Fig. in the temp. regions (a) and (b), magnetic domain transfer and magnetic domain expansion are induced by the irradiation with the low-power reproducing light. If the transfer magnetic field of the recording layer and the coercive force of the reproducing layer have the magnitude relation shown in Fig., the magnified magnetic domain is surely annihilated by the irradiation with the high-power reproducing light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical recording medium and a reproducing method therefor, and more particularly, to a magneto-optical recording medium suitable for high-density recording in which a minute recording magnetic domain extremely smaller than a reproducing light spot can be enlarged and reproduced. The present invention relates to a magneto-optical recording medium and a reproducing method thereof.

[0002]

2. Description of the Related Art A magneto-optical recording medium is a recording medium capable of rewriting recorded information, has a large storage capacity, and is highly reliable. However, with the increase in the amount of information and the downsizing of the apparatus, a higher density recording / reproducing technique is required. To record information on a magneto-optical recording medium, a magnetic field modulation recording method is used in which a magnetic field having a polarity corresponding to a recording signal is applied to a heated portion while irradiating the magneto-optical recording medium with a laser beam. This method enables overwrite recording, and also enables high-density recording, for example, 0.
Recording with a minimum mark length of 15 μm has been achieved. Further, an optical modulation recording system for recording by irradiating light whose power has been modulated according to a recording signal under a constant applied magnetic field has also been put to practical use.

[0003]

However, in order to reproduce a recording mark recorded at high density, an optical reproduction resolution determined by the spot diameter of a reproduction light beam becomes a problem. For example, it is impossible to identify and reproduce a minute mark having a magnetic domain length of 0.15 μm using reproduction light having a spot diameter of 1 μm. As one approach for eliminating the restriction on the reproduction resolution due to the optical spot diameter of the reproduction light, for example, the Journal of Magnetic Society of Japa
Pan, Vol. 17 Supplement No. S1, pp. 201 (1993) has proposed a magnetic super-resolution technique (MSR). This utilizes the fact that a temperature distribution is generated in the magnetic film inside the reproduction light spot when the reproduction light is irradiated to the magneto-optical recording medium, and a magnetic mask is generated in the spot, thereby contributing to the reproduction of the signal. In this case, the typical spot diameter is reduced. If this technique is used, the reproduction resolution can be improved without reducing the actual reproduction light spot diameter. However, in this method, since the effective spot diameter is reduced by the magnetic mask, the amount of light that contributes to the reproduction output decreases, and the reproduction C / N decreases accordingly. As a result, it is difficult to obtain a sufficient C / N.

Japanese Patent Application Laid-Open No. 1-143041 has a first magnetic film, a second magnetic film, and a third magnetic film magnetically coupled to each other at room temperature. When the Curie temperatures are T _C1 , T _C2 and T _C3 , T _C2 > room temperature and T _C2 <T _C1 , T _C3 are satisfied, and the coercive force H _C1 of the first magnetic film is set.
Is sufficiently small in the vicinity of the Curie temperature T _C2 of the second magnetic film, and the coercive force H _C3 of the third magnetic film is sufficiently larger than the required magnetic field in a temperature range from room temperature to a required temperature T _PB higher than T _C2. A reproducing method for a magneto-optical recording medium that performs reproduction by enlarging a recording magnetic domain of a first magnetic film using the recording medium is disclosed. In this method, the magnetic coupling between the first and third magnetic films is interrupted by utilizing the temperature rise of the medium during the irradiation of the reproduction light, and the first magnetic field is applied by the demagnetizing field acting on the recording magnetic domain and the externally applied magnetic field in that state. The domain of the film is enlarged. Although this technique uses the second magnetic film whose Curie temperature is set lower than the temperature of the read section during reproduction, the present invention does not use a magnetic film having such magnetic characteristics.

Japanese Patent Laid-Open No. 8-7350 discloses a magneto-optical recording medium having a reproducing layer and a recording layer on a substrate and capable of reproducing by enlarging the magnetic domain of the recording layer during reproduction. . When reproducing the magneto-optical recording medium, an alternating magnetic field is used as a reproducing magnetic field, and a magnetic field in a direction for expanding the magnetic domain and a magnetic field in the opposite direction are alternately applied to cause the magnetic domain to expand and contract in each magnetic domain. I have.

The present invention has been made to solve the above-mentioned problems of the prior art by a method different from the methods described in JP-A-1-143401 and JP-A-8-7350. Another object of the present invention is to provide a magneto-optical recording medium capable of obtaining a reproduction signal with a sufficient C / N even when a minute magnetic domain is recorded, and a method of reproducing the signal.

Another object of the present invention is to provide a magneto-optical recording medium capable of reliably erasing a magnetic domain enlarged immediately after reproducing a recorded magnetic domain even if the magnetic domain is enlarged during reproduction. And a reproducing method thereof.

[0008]

The magneto-optical recording medium used in the present invention comprises a magneto-optical recording film and an auxiliary magnetic film, and when the reproducing light is irradiated, the recording magnetic domain of the magneto-optical recording film is changed to the auxiliary magnetic film. A magneto-optical recording medium for reproducing signals by magnetically transferring the magnetic film to a film, wherein the auxiliary magnetic film is at least one layer of a magnetic film which transitions from an in-plane magnetic film to a perpendicular magnetic film when a critical temperature is exceeded, and The recording film is a perpendicular magnetization film at a temperature equal to or higher than room temperature, and a magnetic domain larger than the recording magnetic domain of the magneto-optical recording film can be transferred to the auxiliary magnetic film at the time of reproduction by utilizing the magnetic characteristics of the auxiliary magnetic film. It is a magneto-optical recording medium.

The magneto-optical recording medium used in the present invention can be further classified into the following two types of magneto-optical recording media. The first type of magneto-optical recording medium is shown in FIGS. 2A and 2B.
As shown in FIG. 3, the first auxiliary magnetic film 5 is formed on the magneto-optical recording film 6.
A magneto-optical recording film 6, a first auxiliary magnetic film 5, and a second auxiliary magnetic film 4.
Sets the Curie temperatures of the magneto-optical recording film, the first auxiliary magnetic film, and the second auxiliary magnetic film to T _CO , T _C1, and T _C2 , respectively, and the critical temperatures of the first auxiliary magnetic film and the second auxiliary magnetic film, respectively. When T _CR1 and T _CR2 , room temperature <T _CR2 <T
_It has magnetic characteristics satisfying the relationship of _CR1 <T _CO , T _C1 , T _C2 . As shown in FIG. 3, the first auxiliary magnetic film 5 and the second auxiliary magnetic film 4 are in-plane magnetic films from room temperature to a certain critical temperature (T _CR ) above room temperature, and become perpendicular magnetic films above T _CR. Magnetic properties. The magneto-optical recording film 6 is a perpendicular magnetization film at room temperature or higher.

The operation (reproduction) principle of the first type of magneto-optical recording medium will be described below. FIG. 2A shows the magnetization state of each layer before writing and writing after writing a recording magnetic domain on the magneto-optical recording film 6 by a light modulation recording method or the like. When the medium is irradiated with reproduction light having an appropriate power so that the maximum temperature of the magnetic film reaches a desired temperature, first, a region in the first auxiliary magnetic film 5 where the temperature is _{equal to} or higher than T _CR1 is applied. The perpendicular magnetic domains 22 in the magneto-optical recording film 6 are transferred. At this time, in consideration of the temperature profile in the medium when the reproducing light is irradiated as shown in FIG. The reproduction power and T _CR1 are set so as to be transferred to the film 5.

Next, the magnetic domains 21 transferred to the first auxiliary magnetic film 5 are transferred to the second auxiliary magnetic film 4. In the present invention, the first and second auxiliary magnetic films have their critical temperatures of T _CR2 <T.
_Since it is set to be _CR1 , as shown in the temperature profile in the medium of FIG. 8, the region in the second auxiliary magnetic film which can be in the perpendicular magnetization state has a diameter larger than that of the first auxiliary magnetic film. Becomes larger. For this reason, as shown in FIG. 2B, the transfer magnetic domain 23 in the second auxiliary magnetic film 4 has the perpendicular magnetic anisotropy in the region where the second auxiliary magnetic film can be in the perpendicular magnetization state and the transfer magnetic domain 23 in the first auxiliary magnetic film 5. And the exchange coupling force from the perpendicular magnetization of. This magnetic domain expansion is caused by the fact that the in-plane magnetization of the region indicated by W in FIG.
It can be said that this is promoted because the exchange coupling force from the magnetic domain S to the second auxiliary magnetic film 4 is weakened. Due to the magnetic domain expansion, a decrease in the amount of light contributing to the reproduction output by the magnetic mask of the in-plane magnetization is reduced, and reproduction with a high C / N ratio can be performed.

The effect of enlarging the magnetic domain 23 of the second auxiliary magnetic film 4 is maximized when the transfer magnetic domain in the second auxiliary magnetic film 4 is expanded beyond the reproduction light spot diameter. In this state, an extremely large reproduction output determined only by the performance index of the second auxiliary magnetic film 4 and the reproduction beam light, regardless of the size or shape of the magnetic domain recorded in the magneto-optical recording film 6, is obtained. After the reproduction, that is, after the irradiation portion of the reproduction laser beam has moved, the reading portion is cooled to _TCR2 or less, the first and second auxiliary magnetic films are in the in-plane magnetization state, and return to the state of FIG. 2A. Even at the temperature at the time of the reproducing operation as described above, the coercive force of the magneto-optical recording film 6 is sufficiently large, so that the information recorded as the magnetization is completely retained.

A second type of magneto-optical recording medium according to the present invention comprises an auxiliary magnetic film 8 and a magneto-optical recording film 1 as shown in FIG.
0, a non-magnetic film 9 is provided, and the magneto-optical recording film 10 and the auxiliary magnetic film 8 are arranged such that the Curie temperatures of the magneto-optical recording film and the auxiliary magnetic film are T _CO and T _C , respectively. When each temperature is T _CR , room temperature <T _CR <T _CO ,
It is characterized by having magnetic properties satisfying a relationship of T _C.

The principle of reproduction of the second type of magneto-optical recording medium will be described. After a recording magnetic domain is written on the magneto-optical recording film 10 of the medium shown in FIG. 7 by a light modulation recording method or the like in FIG. 6A, the auxiliary magnetic film 8, the non-magnetic film 9, and the magneto-optical recording film 10 before reproduction are performed. 1 schematically shows a magnetization state. When the magneto-optical recording medium is irradiated with reproducing light having an appropriate power so that the maximum temperature of the magnetic film reaches a desired temperature, a region in the auxiliary magnetic film 8 where the temperature becomes _{equal to} or higher than _TCR and a perpendicular magnetization state can be obtained. Occur. Diameter or less on the domain M the size of the region is recorded on the magneto-optical recording film 10, preferably T _CR and the reproducing power such that the reproducing light spot larger than the diameter has been set. The auxiliary magnetic film 8, the coercive force, the distribution shown in FIG. 9 corresponds to the temperature distribution in the region of more than T _CR, the value is sufficient area and its vicinity becomes highest temperature It has magnetic properties that make it smaller.

[0015] has a magneto-optical recording film 10 is the distribution of magnetization shown in FIG. 9 corresponds to the temperature distribution in the region of more than T _CR,
It has magnetic properties such that its value becomes sufficiently large in and near the region where the maximum temperature is reached. Since the magnetic characteristics of each magnetic film are set as described above, only the magnetic domains M in the region where the temperature is high and the magnetization is sufficiently large in the magneto-optical recording film 10 are different from those of the magneto-optical recording film 10 acting in the region of the magnetic domain M. Due to the large magnetostatic coupling force between the magnetic films 8, the transfer is made to an area where the temperature in the auxiliary magnetic film 8 is high and the coercive force is sufficiently small.
Thereby, a sufficient reproduction resolution can be obtained first.

Next, the magnetic domains 6 transferred to the auxiliary magnetic film 8 are
It is considered that No. 3 is enlarged as shown in FIG. 6B due to the perpendicular magnetic anisotropy in the region of T _CR or more and the exchange coupling force from the transferred magnetic domain. Due to this magnetic domain expansion, the reproduction signal is increased similarly to the first type of magneto-optical recording medium, and the C / N ratio is increased.
Is improved. After the reproduction, that is, after the reproduction laser beam moves, the reading section is cooled to _TCR or less, the auxiliary magnetic film 8 becomes an in-plane magnetic film, and returns to the state of FIG. 6A.

According to the first aspect of the present invention, the magnitude of the magneto-optical effect is detected by irradiating a reproducing light to a magneto-optical recording medium having a magneto-optical recording film as a perpendicular magnetization film at a temperature equal to or higher than room temperature. In the method of reproducing a magneto-optical recording medium that reproduces a signal recorded by the method, as the magneto-optical recording medium,
A first auxiliary magnetic film and a second auxiliary magnetic film are sequentially stacked on the magneto-optical recording film, and when the first auxiliary magnetic film and the second auxiliary magnetic film exceed a critical temperature, a transition from an in-plane magnetic film to a perpendicular magnetic film is made. A magnetic film, wherein the magneto-optical recording film, the first auxiliary magnetic film and the second auxiliary magnetic film have Curie temperatures of T _CO and T _{CO of} the magneto-optical recording film, the first auxiliary magnetic film and the second auxiliary magnetic film, respectively. T
And _C1 and T _C2, the critical temperature of the first auxiliary magnetic layer and the second auxiliary magnetic film is taken as T _CR1 and T _CR2, respectively, and at room temperature _{<T CR2 <T CR1 <T} CO, T C1, T C2 Using a magneto-optical recording medium having magnetic characteristics satisfying the following relationship, and reproducing the recording signal by irradiating the magneto-optical recording medium with reproduction light whose power has been modulated in the same cycle as the reproduction clock or in a cycle of an integral multiple of the reproduction clock. A method for reproducing a magneto-optical recording medium is provided.

According to a second aspect of the present invention, a magneto-optical recording medium having a magneto-optical recording film, which is a perpendicular magnetization film, is irradiated with reproduction light at a temperature equal to or higher than room temperature to reduce the magnitude of the magneto-optical effect. In a reproducing method of a magneto-optical recording medium for reproducing a signal recorded by detecting, an auxiliary magnetic film that transitions from an in-plane magnetic film to a perpendicular magnetic film when a critical temperature is exceeded is used as the magneto-optical recording medium. The magneto-optical recording film and the auxiliary magnetic film are provided on the magneto-optical recording film via the optical magnetic recording film, and the Curie temperatures of the magneto-optical recording film and the auxiliary magnetic film are respectively set to T _CO ,
And T _C, the critical temperature of the auxiliary magnetic film is taken as T _CR, respectively, using a magneto-optical recording medium with magnetic properties satisfying the relation of room temperature _{<T CR <T CO, T} C, the magneto-optical recording There is provided a reproducing method for a magneto-optical recording medium, wherein a recording signal is reproduced by irradiating a medium with a reproduction light whose power is modulated at the same cycle as the reproduction clock or at an integral multiple of the reproduction clock.

[0019] The reproduction light is power modulated reproducing light power Pr ₁ and Pr ₂ in a cycle of the same period or integer multiple recovered clocks, one of the reproducing light power said auxiliary magnetic film of the Pr ₁ and Pr ₂ It is desirable that the power be a power that causes the magnetic domain expansion.

Here, the principle of the reproducing method according to the second embodiment of the present invention will be described with reference to the schematic diagram of the reproducing method shown in FIG. This reproducing method uses the second type of magneto-optical recording medium shown in FIG. First, a predetermined recording pattern as shown in FIG. 11A is recorded on a magneto-optical recording medium by using a light modulation recording method or the like on a second type of magneto-optical recording medium. In the figure, recording marks are recorded at the shortest mark pitch DP, and the recording mark length DL is set so that DL = DP / 2. At the time of reproduction, pulse laser light modulated to two kinds of reproduction powers Pr2 and Pr1 as reproduction laser light has a period DP synchronized with the recording mark position and a high power Pr2 as shown in FIG. Irradiation is performed so that the light emission width becomes DL. Light with a low reproducing power Pr1 is always illuminated in an erased state (a part without a recording mark), and light with a high reproducing power Pr2 is radiated in a recording state (a part where a recording mark exists) and an erasure state.

FIG. 11 (c) shows a reproduction signal waveform obtained by irradiating the reproduction pulse laser as shown in FIG. 11 (b). On the other hand, FIG. 11D shows a reproduction waveform when the same track is reproduced by continuous light having a constant reproduction light power. Here, of Pr2 and Pr1, Pr2 is selected so as to be a recording power at which the magnetic domain expansion of the auxiliary magnetic film 8 occurs, as will be described later, and Pr1 is selected as a power at which the magnetic domain expansion disappears. By selecting the playback power in this way,
The amplitude H _pl between the recorded state and the erased state observed in the pulsed light reproduction can be set to H _pl > H _dc with respect to the amplitude H _dc in the constant laser light reproduction. Magnetization information recorded in each magnetic domain of the film can be independently enlarged and reproduced without being affected by adjacent magnetic domains.

According to a third aspect of the present invention, a reproducing method for a magneto-optical recording medium for reproducing a recorded signal by irradiating the magneto-optical recording medium with reproducing light and detecting the magnitude of a magneto-optical effect. Wherein, as the magneto-optical recording medium, a magneto-optical recording film having perpendicular magnetization, and an auxiliary magnetic film that transitions from an in-plane magnetization film to a perpendicular magnetization film when the critical temperature Tcr is exceeded, via a non-magnetic film, A magneto-optical recording medium having magnetic properties satisfying a relationship of room temperature <Tcr <Tcomp <Tco <Tc between the Curie temperature Tco of the magneto-optical recording film and the Curie temperature Tc and the compensation temperature Tcomp of the auxiliary magnetic film,
While applying a DC magnetic field to the magneto-optical recording medium, at least two pulses having the same period as the reproduction clock or a period of an integral multiple
The recording magnetic domains of the magneto-optical recording film are transferred to the auxiliary magnetic film by irradiating the reproducing light whose power has been modulated to the various optical powers Pr ₁ and Pr ₂ , the transferred magnetic domains are enlarged, and the expanded magnetic domains are enlarged. A reproduction method of a magneto-optical recording medium, wherein the reproduction of the recording signal is performed through a step of reducing or eliminating the size of the recording signal.

In the reproducing method of the present invention, the optical power Pr _{1 of the} reproducing light is used to transfer the recording magnetic domain of the magneto-optical recording film to the auxiliary magnetic film by heating the auxiliary magnetic film to a temperature of Tcr to Tcomp and to enlarge the magnetic domain. Preferably, the optical power Pr _{2 of the} reproduction light is a power for heating the auxiliary magnetic film to a temperature of Tcomp to Tco to reduce or eliminate the enlarged magnetic domain.

Further, in this reproducing method, the temperature curve A of the transfer magnetic field generated from the external magnetic field Hex and the magneto-optical recording film under the condition that the external magnetic field Hex is applied to the magneto-optical recording medium.
And the temperature curve B of the perpendicular magnetic coercive force of the auxiliary magnetic film intersects between room temperature and the compensation temperature Tcomp of the auxiliary magnetic film, and the temperature curve A and the temperature curve B are different from each other. And the curable temperature of the magneto-optical recording film.
It is preferable to use a magneto-optical recording medium that intersects with the temperature Tco.

The transfer magnetic field is the sum of the static magnetic field Ht from the magneto-optical recording film and the external magnetic field Hex, and the vertical coercive force of the auxiliary magnetic film is the vertical coercive force Hr of the magnetic domain to be transferred and the magnetic coercive force Hr of the magnetic domain to be transferred. With the exchange coupling force Hw received from the adjacent magnetic domain.

In order to transfer the recording magnetic domain marked on the recording layer to the reproducing layer and obtain a high reproducing signal, a method of enlarging and reading the transferred signal of the reproducing layer is described in "Magneto-Amplifying Magneto-Optical System (MAMMOS)". ) ", Which has been confirmed by the present applicants using an external magnetic field modulation reproduction method (Japanese Patent Application No. 8-182901). In this external magnetic field modulation reproduction method,
At the time of reproduction, enlargement and reduction of magnetic domains transferred to the reproduction layer are performed using an alternating magnetic field. In the present invention, a magneto-optical system that performs the above-described magnetic amplification is subjected to experiments from various aspects, and as a result of conducting detailed analysis and examination, the reproduction light power is modulated into two or more types using a DC magnetic field. We have succeeded in developing a method that can surely realize the expansion and contraction of the transferred magnetic domain.

The principle of the reproducing method of the magneto-optical recording medium according to the third aspect of the present invention will be described. The reproducing method includes a magneto-optical recording medium including a magneto-optical recording film having perpendicular magnetization and an auxiliary magnetic film that transitions from an in-plane magnetic film to a perpendicular magnetic film when the critical temperature Tcr is exceeded, via a non-magnetic film. Used. FIG. 18 shows an example of the structure of this type of magneto-optical recording medium. FIG.
Has a dielectric film 3, an auxiliary magnetic film 8, a non-magnetic film 3, a magneto-optical recording film 10 and a protective film 7 laminated on a substrate 1. The auxiliary magnetic film 8 has a compensation temperature Tcomp between the critical temperature Tcr and its Curie temperature Tc. The magneto-optical recording medium 90 has a Curie temperature Tco of the magneto-optical recording film 10 and a critical temperature of the auxiliary magnetic film 8. Room temperature <T between Tcr, Curie temperature Tc and compensation temperature Tcomp
The relationship cr <Tcomp <Tco <Tc is satisfied.

In the reproducing method of the present invention, reproduction is performed by irradiating the magneto-optical recording medium 90 having the above-mentioned magnetic characteristics with reproducing light whose optical power has been modulated while applying an external DC magnetic field. Here, a constant DC magnetic field He is applied to the magneto-optical recording medium 90.
FIG. 20 shows the magnetic characteristics of the magneto-optical recording film 10 and the auxiliary magnetic film 8 of the magneto-optical disk 90 when x is applied in the recording direction. The magnetic temperature curve A in the figure indicates that the magneto-optical recording film 10 (hereinafter simply referred to as a recording layer) extends from the auxiliary magnetic film 8.
The temperature change of the transfer magnetic field (static magnetic field) generated by the magnetization of the recording layer with respect to (hereinafter simply referred to as a reproduction layer) is shown. Note that the transfer magnetic field of the curve A indicates the magnitude of the magnetic field obtained by adding the offset of the external magnetic field Hex. Therefore,
Depending on the direction of the magnetic domain of the recording layer, (H
A magnetic field having a magnitude of ex-Ht) and a magnetic field having a magnitude of (Hex + Ht) exist at the boundary of the Curie temperature Tco of the recording layer, and these constitute a curve A. In the figure, the downward direction is the recording direction, and Hex is also applied downward. Here, the external magnetic field Hex is adjusted to be smaller than the magnitude of the static magnetic field Ht in the initialization direction generated from the magnetization of the recording layer at room temperature. As shown, there are upward (negative) and downward (positive) depending on the magnetization direction of the recording magnetic domain of the recording layer.

The magnetic temperature curve B shows the temperature change of the coercive force in the perpendicular direction of the reproducing layer in the state having perpendicular magnetization.
This coercive force includes a magnetic field Hw corresponding to a virtual magnetic field which is regarded as being applied to the pure coercive force Hr of the magnetic domain of the reproducing layer by generation of a magnetic wall of the reproducing layer.
(In other words, the exchange coupling magnetic field in the in-plane direction of the reproducing layer) is expressed as Hr + Hw. That is, Hr + Hw indicates a magnetic field required for performing magnetization reversal in a direction perpendicular to the reproduction layer film surface. As shown in FIG. 20, the magnetization in the direction perpendicular to the film surface of the reproducing layer appears above the critical temperature Tcr (T0 in the figure) at which the reproducing layer becomes a perpendicular magnetic film, and at the compensation temperature Tcomp, the magnetization of the reproducing layer Is zero, the coercive force shows a maximum.

The temperature curves A and B in FIG. 20 are divided into three areas (a) to (c) as shown in FIG. These three areas (a) to (c) correspond to i) magnetic domain transfer from the recording layer to the reproducing layer in the reproducing method of the present invention shown in FIG. iii) Corresponding to the three steps of disappearance of the expanded magnetic domain. For this reason,
The magnetic characteristics required for the recording layer and the reproducing layer in the areas (a) to (c) of FIG. 20 will be described with reference to FIG. The arrows in the recording layer and the reproducing layer shown in FIG. 21A indicate the directions of the magnetic moment of the rare earth metal in each magnetic domain.

Area (a) is a temperature area where magnetic domain transfer is performed from the recording layer to the reproduction layer in the reproduction method of the present invention, and belongs to a temperature range of T0 to T1 in the drawing. T0 means critical temperature Tcr, and T1 is Hex of magnetic temperature curve A.
-Ht is the temperature at which the magnetic temperature curve B first intersects. The temperature range T0 to T1 can be achieved by adjusting the optical power of the reproduction light to a relatively low power as described later. In order to actually perform magnetic transfer as shown in (1) of FIG. 21A in this temperature range, the magnitude of the transfer magnetic field exceeds the coercive force in the vertical direction of the reproducing layer in this temperature range. I have to do it. That is, when the magnetization recorded in the recording layer is in the ↓ direction (recording direction), He is used.
The transfer magnetic field represented by x + Ht is Hr + Hw or −
(Hr + Hw) (magnetic domain transfer requirement). When the magnetization recorded in the recording layer is in the ↑ direction (erasing direction), the negative transfer magnetic field represented by Hex-Ht causes the coercive force H in the perpendicular direction of the reproducing layer to change.
It must be smaller than r + Hw or-(Hr + Hw) (magnetic domain transfer requirement).

On the other hand, comparing the magnetic temperature curves A and B in the area (a) of FIG.
It can be seen that the relationship (a3) holds. Hr <Hex + Ht-Hw (a1) -Hr> Hex-Ht + Hw (a2) Hr> Hex-Ht-Hw (a3)

Therefore, the area (a) satisfies the above magnetic domain transfer requirement, and it can be transferred to the reproducing layer regardless of the magnetization direction of the recording magnetic domain of the recording layer. (1) of FIG. 21 (a)
5A shows a case where the magnetization in the ↓ direction recorded in the magnetic domain 210 of the recording layer is transferred to a region exceeding the temperature T0 in the reproduction light spot of the reproduction layer to form the transfer magnetic domain 201a.

Next, in area (b) of FIG.
As shown in (2) and (3), magnetic domain expansion of the magnetic domain 201b transferred to the reproducing layer is performed. This temperature region is a range indicated by T1 to T2 in the drawing. The temperature T2 is a temperature at which the Hex-Ht side of the magnetic temperature curve A crosses the magnetic temperature curve B on the high temperature side. In the magneto-optical disk having the magnetic characteristics shown in FIG. 20, T2 substantially matches the compensation temperature Tcomp of the reproducing layer in relation to the external magnetic field Hex (between the compensation temperature Tcomp and the Curie temperature Tco of the recording layer). , Very close to the compensation temperature Tcomp). In this temperature region, as shown in (2) of FIG. 21A, both sides of the magnetic domain 201b transferred to the reproducing layer were heated to T0 to T1 in the reproducing light spot,
There are magnetic domains 203, 203 'subjected to magnetic transfer from the upward magnetic domains 212, 212' of the recording layer. In order for the magnetic domain 201b transferred to the reproducing layer to start expanding in the in-plane direction, the magnetic domains 203 and 203 'on both sides thereof need to be oriented in the recording direction (↓ direction) in the same manner as the magnetic domain 201b. . Here, the magnetic domains 203 and 203 ′ are formed by the external magnetic field He.
x indicates an upward static magnetic field H from the magnetic domain 212 of the recording layer immediately above
t, the transfer magnetic field (Hex-Ht) (total ↑ direction) is added, while the exchange coupling magnetic field Hw (downward) from the magnetic domain 201b and the protection for reversing the magnetization of the magnetic domains 203 and 203 'themselves. It has a perpendicular coercive force including the magnetic force Hr. Therefore, the coercive force in the vertical direction (Hr + H) is larger than the transfer magnetic field (Hex−Ht) of the magnetic domains 203 and 203 ′.
If w) is increased, the magnetic domains of the magnetic domains 203 and 203 'are reversed (requirement of magnetic domain reversal).

In the area (b), the magnetic temperature curve A
It can be seen from the magnitude relation between B and B that the following relational expression holds. Hr <Hex + Ht-Hw (b1) -Hr <Hex-Ht + Hw (b2)
This is the magnetic domain reversal condition itself in which the vertical coercive force (Hr + Hw) is larger than the transfer magnetic field Hex-Ht (upward). Therefore, in the area (b), as shown in FIG.
The magnetic domain expansion of the magnetic domain 201b of the reproducing layer as shown in (3) occurs. The relationship (b2) indicates that in the temperature area (b), when there is no magnetic domain in the recording direction in the recording layer, no downward magnetic domain appears in the reproducing layer. Note that FIG.
In (3) of (a), both sides of the enlarged magnetic domain 201b are T0 to T0.
Because of the temperature region of T1, the magnetic domains 212, 2 of the recording layer
磁 -oriented magnetic domains 203 and 20 transferred from 12 ′
3 'exists.

Next, in the area (c), FIG.
As shown in (4), the transferred and enlarged magnetic domains are reversed (disappear), and magnetic domains 201c in the erasing direction are formed. This temperature range is from T2, which slightly exceeds the compensation temperature of the reproducing layer, to Curie temperature Tco of the recording layer. The enlarged and reproduced magnetic domains can be eliminated or reduced by applying a reproducing magnetic field in the erasing direction, that is, by using an alternating magnetic field as the reproducing magnetic field. However, in the reproducing method of the present invention, a DC magnetic field is used. The enlarged magnetic domain is eliminated by power-modulating the reproduction light to a power higher than the reproduction light power used for magnetic transfer and enlargement.
As will be described later in a second embodiment of the reproducing method of the magneto-optical recording medium of the present invention, the reproducing light power may be further modulated to eliminate the enlarged magnetic domain.

The principle that the expanded magnetic domain is reversed (disappears) in the area (c) will be described with reference to FIG. FIG. 22 shows the (TbFe) of the rare earth-transition metal shown in (2) of FIG.
The temperature change of the direction and magnitude of the sublattice magnetization of the rare earth metal and the transition metal in the magnetic domain 210 of the recording layer of the recording layer and the rare earth-transition metal (GdFeCo alloy) of the reproducing layer of the rare earth-transition metal (GdFeCo alloy) magnetically transferred therefrom will be described. FIG. When the temperature of the reproducing layer is lower than the compensation temperature Tcomp, as shown in FIG. 22A, the magnetization of the rare earth metal of the reproducing layer is dominant, and the recording layer of the transfer source (the magnetization of the transition metal is dominant). Is parallel to the magnetization direction. Next, when the reproducing layer exceeds the compensation temperature Tcomp by the irradiation of the high power laser according to the reproducing method of the present invention,
The magnetic moment of the transition metal in the reproducing layer becomes dominant. Here, based on the magnitude relationship between the magnetic temperature curves A and B of the reproducing layer and the recording layer in the area (C) shown in FIG.
It can be seen that 1) and equation (C2) hold.

Hr <Hex + Ht−Hw (C1) Hr <Hex−Ht−Hw (C2)

That is, the coercive force Hr of the magnetic domain 201b is
The total magnetic field (Hex + H) in the recording direction acting on the magnetic domain 201b
t-Hw or Hex-Ht-Hw). As a result, when the temperature of the reproducing layer is equal to or higher than the compensation temperature Tcomp (strictly, equal to or higher than T2), as shown in FIG. I do. Therefore, the magnetic moment of the downward rare earth metal in the enlarged magnetic domain 201b shown in (3) of FIG. 21 (a) is the temperature of the area (c), that is, the compensation temperature Tcomp.
Reversal occurs in the region heated as described above, and a reversal magnetic domain 201c is generated ((4) in FIG. 21A). The inverted magnetic domain 201c
The magnetic domains 201d and 201d 'on both sides of the
To T2, it has the same magnetization direction as the enlarged magnetic domain 201b.

In the reproducing method according to the present invention, the three temperature areas (a) to (c) are, as shown in FIG.
The reproducing light power is changed into at least two levels of power Pr ₁ and P
This can be achieved by modulating to r ₂ . That is, the optical power Pr ₁ of the reproducing light is set to a power capable of transferring the recording magnetic domain of the magneto-optical recording film to the reproducing layer and expanding the magnetic domain by heating the auxiliary magnetic layer to a temperature of Tcr to Tcomp. The light power Pr ₂ of the light may be a power for heating the auxiliary magnetic layer to a temperature of Tcomp to Tco to reduce or eliminate the enlarged magnetic domain. And
The use as a reproduction light with Pr ₁ / Pr ₂ reproducing light power modulation is synchronized with the reproduction clock, the recording magnetic domain of the recording layer, i) transfer to the reproducing layer, ii) the expansion of the copied magnetic domain, and iii) expansion It can be reproduced through the step of disappearance of the magnetic domain.

According to a fourth aspect of the present invention, in a magneto-optical recording medium having at least a magneto-optical recording film on a substrate, a magneto-optical recording film having perpendicular magnetization and an in-plane magnetization film when the critical temperature Tcr is exceeded. And a supplementary magnetic film which changes from a non-magnetic film to a perpendicular magnetization film via a nonmagnetic film, and a room temperature <Tcr between the Curie temperature Tco of the magneto-optical recording film and the Curie temperature Tc and the compensation temperature Tcomp of the supplementary magnetic film. <Tcomp <Tco <
Under the condition that the relationship Tc is established and the external magnetic field Hex is applied to the magneto-optical recording medium, the temperature curve A of the external magnetic field Hex and the transfer magnetic field generated from the magneto-optical recording film and the temperature curve B of the perpendicular coercive force of the auxiliary magnetic film B Intersects between room temperature and the compensation temperature Tcomp of the auxiliary magnetic film, and the temperature curve A and the temperature curve B correspond to the compensation temperature Tco of the auxiliary magnetic film.
The magneto-optical recording medium is provided, wherein the magneto-optical recording medium crosses between mp and the Curie temperature Tco of the magneto-optical recording film.

The magneto-optical recording medium according to the fourth aspect of the present invention is a magneto-optical recording medium suitable for the reproducing method according to the third aspect of the present invention. By reproducing the magneto-optical recording medium using the reproducing method according to the third aspect of the present invention, even if the magnetic domain is smaller than the light spot, it is independent of the other magnetic domains and the reproduced signal is amplified. Can be played.

According to a fifth aspect of the present invention, on a substrate:
In a magneto-optical recording medium having at least a magneto-optical recording film, a first auxiliary magnetic film that transitions from a perpendicular magnetization film to an in-plane magnetization film when the critical temperature Tcr ₁₁ is exceeded, and an in-plane magnetization film when the critical temperature Tcr ₁₂ is exceeded A magneto-optical recording medium is provided, comprising: a second auxiliary magnetic film that transitions to a perpendicular magnetization film.

An example of the structure of the magneto-optical recording medium according to the fifth embodiment of the present invention will be described with reference to FIG. As shown in FIG. 23, the magneto-optical recording medium 100 includes a first auxiliary magnetic film 28, a non-magnetic film 29, and a second auxiliary magnetic film 24 in this order on the magneto-optical recording film 10. The magneto-optical recording film 10 is a perpendicular magnetic film, the first auxiliary magnetic film 28 is a magnetic film that changes from a perpendicular magnetic film to an in-plane magnetic film when the critical temperature Tcr ₁₁ is exceeded, and the second auxiliary magnetic film 24 is a critical magnetic film. beyond temperature Tcr ₁₂ from the in-plane magnetization film is a magnetic film which transfers to the perpendicular magnetization film. Here, it is assumed that the materials and compositions of the first auxiliary magnetic films are adjusted so that the critical temperature Tcr ₁₁ of the second auxiliary magnetic films is higher than the critical temperature Tcr ₁₂ of the second auxiliary magnetic films. Here, the second auxiliary magnetic film 24 functions as a reproducing layer.

The reproduction principle of the magneto-optical recording medium according to the fifth embodiment will be described with reference to FIGS. FIG. 25 (a)
FIG. 24 conceptually shows a main part of the magneto-optical recording medium shown in FIG. 23, and it is assumed that upward magnetization is recorded in the magnetic domain 22 of the magneto-optical recording film 10. The magneto-optical recording film 10 and the first auxiliary magnetic layer 28 are exchange-coupled, and the same magnetization as the magnetic domain 22 is transferred to the magnetic domain 28 a of the first auxiliary magnetic layer 28 immediately below the magnetic domain 22. Here, when the reproducing light is irradiated to the magneto-optical recording medium and the temperature starts to rise, in the region exceeding the critical temperature Tcr ₁₂ in the second auxiliary magnetic film 24, the transition from in-plane magnetization to perpendicular magnetization occurs. The transferred region corresponds to the magnetic domains 24a and 24b in FIG. At the time of this transition, the magnetic domain 24a has the same magnetization as the magnetic domain 22 as shown in FIG. Align in the direction. FIG. 25 (b) shows a process of increasing the temperature of the magneto-optical recording medium by the reproduction light, and before the temperature T of the magneto-optical recording medium reaches the highest temperature and Tcr ₁₂ <T <.
The magnetization state in the range of Tcr ₁₁ is shown. In this state, the recording layer 10, the first auxiliary magnetic layer 28, and the second auxiliary magnetic layer 24 are magnetically coupled (magnetostatic coupling), and all exhibit perpendicular magnetization. In addition, on both sides of the magnetic domain 24a,
First auxiliary magnetic film 28 on both sides of magnetic domain 22 and immediately below them
There is a small magnetic domain 24b having a downward magnetization due to the magnetostatic coupling force from the downward magnetic domain.

Further, when the temperature of the medium rises to the maximum heating temperature and the high temperature region of the first auxiliary magnetic layer 28 exceeds the critical temperature Tcr ₁₁ , the coercive force of the first auxiliary magnetic layer 28 decreases. The first auxiliary magnetic layer 28 in the high temperature region changes from perpendicular magnetization to in-plane magnetization. As a result, magnetic domains 28a 'are formed as shown in FIG.

FIG. 26 shows the relationship between the magnetization state and the temperature distribution of the medium shown in FIG. 25 (c). In this magneto-optical recording medium, since Tcr ₁₂ <Tcr ₁₁ as described above,
As shown in FIG. 26, the region exceeding Tcr ₁₂ in the temperature distribution of the medium is wider than area of more than Tcr _11. here,
In a region exceeding Tcr ₁₂ in the second auxiliary magnetic layer 24, a transition from in-plane magnetization to perpendicular magnetization occurs, and in a region exceeding Tcr ₁₁ in the first auxiliary magnetic layer 24, a transition from perpendicular magnetization to in-plane magnetization occurs. Metastasis is taking place. Therefore, the perpendicular magnetic domain 24a 'of the second auxiliary magnetic layer 24 is larger than the in-plane magnetic domain 28a' of the first auxiliary magnetic layer 24. Here, the reproducing light power and Tcr ₁₂ are adjusted so that the region exceeding Tcr ₁₂ in the second auxiliary magnetic layer 24 becomes larger than the magnetic domain of the recording layer 10 when the reproducing light is irradiated.

On the other hand, the magnetic domains 28a 'of the first auxiliary magnetic layer 28
Has an in-plane magnetization, so that the second direction from the magneto-optical recording film 10 such as a static magnetic field or a leakage magnetic field due to the ↓ -direction magnetization on both sides of the magnetic domain 22.
The magnetic effect on the auxiliary magnetic film 24 can be cut off, thereby promoting the expansion of the magnetic domain 24a '. The reproduction signal increases due to the magnetic domain expansion. Also, it is considered that the C / N is improved by the magnetic blocking function of the first auxiliary magnetic film 28. In order to make the magnetic blocking function of the first auxiliary magnetic film 28 more effective, the first auxiliary magnetic film must be formed such that the region exceeding Tcr ₁₁ in the first auxiliary magnetic layer 24 becomes larger than the recording magnetic domain 11 during reproduction. Preferably, a critical temperature Tcr ₁₁ and a reproduction light power of 28 are selected. In order to sufficiently increase the reproduction signal through magnetic domain expansion in the second auxiliary magnetic layer 24, the Tcr in the second auxiliary magnetic layer 24 during reproduction is required.
_It is preferable that the critical temperature Tcr ₁₂ and the reproducing light power of the second auxiliary magnetic film 24 are selected so that the region exceeding ₁₂ becomes larger than the recording magnetic domain 11. Further, in order to simultaneously satisfy the effect of promoting the magnetic domain expansion and the function of magnetically blocking the first auxiliary magnetic film 28, the critical temperature T of the first auxiliary magnetic film 28 is required.
cr ₁₁ and the critical temperature Tcr ₁₂ of the second auxiliary magnetic film 24 (Δ
It is desirable to appropriately adjust T = Tcr ₁₁ −Tcr ₁₂ ).

The effect of the magnetic domain expansion of the second auxiliary magnetic film 24, that is, the reproduction signal intensity is maximized when the transfer magnetic domain in the second auxiliary magnetic film 24 is expanded beyond the reproduction light spot diameter. In this state, the second auxiliary magnetic film 24 irrespective of the size or shape of the magnetic domain recorded in the magneto-optical recording film 10
An extremely large reproduction output determined only by the figure of merit and the reproduction light beam is obtained. After the reproduction, that is, after the irradiation part of the reproduction laser beam has moved, the reading part is cooled to Tcr ₁₂ or less, and the second auxiliary magnetic film is in an in-plane magnetization state.
Return to the state of (a). Since the coercive force of the magneto-optical recording film 10 is sufficiently large even at the above-described temperature during the reproducing operation, the information recorded as the magnetization is completely retained.

In the magneto-optical recording medium according to the fifth embodiment of the present invention, as shown in FIG. 24, the Curie temperature Tco of the magneto-optical recording film and the Curie temperature Tc of the first auxiliary magnetic film.
₁ and the critical temperature Tcr _11, between the Curie temperature Tc ₂ and the critical temperature Tcr _{1 2} of the second auxiliary magnetic film at room temperature <Tcr
_{12 <Tcr 11 <Tco, Tc} 1, it is desirable that the Tc ₂ is relationship is established.

[0051]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments and examples of a magneto-optical recording medium and a reproducing method of the present invention will be described below with reference to the drawings.

Embodiment 1 [Manufacture of a magneto-optical recording medium belonging to the first type] An example of the structure of a magneto-optical recording medium belonging to the first type of the present invention will be described with reference to FIG. As shown in FIG.
The magneto-optical recording medium 11 belonging to the type (1) includes a transparent substrate 1 on which a desired preformat pattern 2 is formed on one side and a dielectric film 3 formed on the preformat pattern 2.
A second auxiliary magnetic film 4 formed on the dielectric film 3,
First auxiliary magnetic film 5 formed on second auxiliary magnetic film 4
And a magneto-optical recording film 6 formed on the first auxiliary magnetic film 5
And a protective film 7 formed on the magneto-optical recording film 6.

In the structure shown in FIG. 1, the transparent substrate 1 is formed by molding a transparent resin material such as polycarbonate or amorphous polyolefin into a desired shape, or on one side of a glass plate formed into a desired shape. An arbitrary substrate having a light-transmitting property such as a substrate in which a transparent resin film on which a desired preformat pattern 2 has been transferred can be used. The dielectric film 3 is provided for causing a reproduction light beam to cause multiple interference in the film and increasing an apparent Kerr rotation angle, and is made of, for example, SiN having a larger refractive index than the transparent substrate 1. It can be formed of an inorganic dielectric. The protective film 7 is for protecting the film bodies 3 to 6 laminated between the substrate 1 and the protective film 7 from a chemical adverse effect such as corrosion, and is made of, for example, a SiN film. The magneto-optical recording film 6 is a perpendicular magnetization film exhibiting perpendicular magnetic anisotropy at a temperature equal to or higher than room temperature. For example, TbFeCo, DyFeC
o, an amorphous alloy of a rare earth and a transition metal such as TbDyFeCo is most preferable. it can.

First auxiliary magnetic film 5 and second auxiliary magnetic film 4
As shown in FIG. 3 is a plane magnetization film to room temperature above room certain critical temperature from _{(R.T.) (T CR),} T CR
In the above, it has the magnetic property of transitioning to the perpendicular magnetization film. In addition, in this specification, room temperature indicates an ambient temperature at which a magneto-optical recording medium is normally used, and differs depending on a place of use.
It is not particularly limited to a specific temperature.

FIG. 3 shows θ _KR / θ _KS (θ _KR : residual Kerr rotation angle, θ _KS : saturation Kerr rotation angle) obtained from a hysteresis loop of the Kerr effect when an external magnetic field is applied in a direction perpendicular to the film surface. 3) shows the temperature dependence of the present invention. As the material of the auxiliary magnetic film, for example, GdFeCo, GdFe, GdT
An amorphous alloy of a rare earth and a transition metal such as bFeCo and GdDyFeCo is most preferred.

The dielectric film 3, the second auxiliary magnetic film 4, the first auxiliary magnetic film 5, the magneto-optical recording film 6, and the protective film 7 are, for example,
It can be formed by a dry process such as continuous sputtering by a magnetron sputtering apparatus.

An example of manufacturing a magneto-optical recording medium belonging to the first type shown in FIG. 1, that is, a magneto-optical disk sample will be described below. The sample is formed by forming a dielectric film made of a SiN film on a glass substrate having a preformat pattern,
a second auxiliary magnetic film made of d ₂₅ Fe ₅₆ Co ₁₉ film (II);
a first auxiliary magnetic film made of a d ₂₈ Fe ₅₃ Co ₁₉ (I) film;
A magneto-optical recording film made of a Tb ₂₁ Fe ₆₆ Co ₁₃ film;
A protective film composed of a film was sequentially formed by sputtering to form a protective film. Table 1 shows the thickness and magnetic characteristics of each auxiliary magnetic film and magneto-optical recording film in this case. T _C in the table
Represents the Curie temperature, and T _CR represents a critical temperature at which the in-plane magnetic film of the auxiliary magnetic film changes to a perpendicular magnetic film.

[0058]

Table 1 Material Thickness T _C T _CR (nm) (° C.) (° C.) Magneto-optical recording film TbFeCo 50 270-First auxiliary magnetic film GdFeCo (I) 60> 400 200 Second auxiliary magnetic film GdFeCo (II) 50> 400 90

A data recording area of the disk manufactured as described above is irradiated with a laser beam in a pulsed manner at a constant period, and an external magnetic field is modulated in accordance with a recording signal to perform recording. The test signal was recorded.
The duty ratio of the recording light pulse was 50%. Test signals were applied so that recording marks of various recording mark lengths were formed. Next, the numerical aperture NA of the objective lens = 0.
55, using a pickup with a laser wavelength of 780 nm,
Recording marks of various lengths were reproduced with a linear velocity of 7.5 m / sec, a reproduction power of 2.5 mW, and an externally applied magnetic field during reproduction of zero. FIG. 4 shows the measurement results of the recording magnetic domain length dependence of the reproduction CN ratio (C: carrier level, N: noise level).

FIG. 4 also shows data of two types of conventional magneto-optical recording media for comparison. Dotted line data is reproduction data of the conventional magneto-optical recording medium shown in FIG.
o is used. The data indicated by the dashed line indicates that the TbFeCo magneto-optical recording film 16 and the GdFeC
o These are the results for a magnetic super-resolution (MSR) disk constituted by a two-layer magnetic film of the first auxiliary magnetic film 15. From the results shown in FIG. 4, it can be seen that the sample disk according to the present embodiment (data is a solid line) has a
It can be seen that a remarkably high reproduction C / N can be obtained as compared with the two types of conventional disks. Therefore, according to the present invention, extremely small recording marks exceeding the conventional reproduction limit can be reproduced, and the recording density can be improved.

In the present embodiment, the three magnetic films of the magneto-optical recording film 6, the first auxiliary magnetic film 5, and the second auxiliary magnetic film are brought into contact with each other and laminated, and the films are exchange-coupled. A non-magnetic film is inserted between the magneto-optical recording film 6 and the first auxiliary magnetic film 5, or between the first auxiliary magnetic film 5 and the second auxiliary magnetic film 4, or both. The space may be magnetostatically coupled.

[0062] Further, in this embodiment, using the auxiliary magnetic film two layers, each layer of the T _CR (temperature threshold which varies from in-plane magnetization film to a perpendicular magnetization film) T _CR1> T _CR2>. . . > T
_CRn > room temperature (where T _CRi is T _cr of the i-th auxiliary magnetic film) and n (n ≧ 3) auxiliary magnetic films may be sequentially laminated and used. However, in this case, the first auxiliary magnetic film is provided on the magneto-optical recording film 6 side, and the n-th auxiliary magnetic film is provided on the dielectric film 3 side.

In order to make the temperature profile of the medium when irradiated with the reproducing light beam into a desired shape or to reduce the linear velocity dependence of the temperature profile, an appropriate thermal control of the thermal conductivity is performed. A film may be provided on the protective film 7 of the magneto-optical recording medium 11.

Further, in this embodiment, reproduction was performed with a normal DC laser beam. However, reproduction was performed with a pulse laser beam having a frequency corresponding to the shortest mark length as in a second embodiment described later, and more excellent reproduction was performed. It is also possible to obtain C / N.

Further, in order to obtain a better reproduction CN ratio, the Kerr rotation angle θk is equal to or larger than θk of the second auxiliary magnetic film 4 at the maximum temperature of the medium when the reproduction light is irradiated, and at room temperature or higher. The magnetic film for reproduction which is a perpendicular magnetization film is replaced with the dielectric film 3.
And the second auxiliary magnetic film 4.

Embodiment 2 In this embodiment, a medium belonging to the second type of magneto-optical recording medium of the present invention and a specific reproduction method for performing reproduction while changing the reproduction laser beam in a pulse shape using such a medium. Here is an example. A medium having the structure shown in FIG. 7 is used as a magneto-optical recording medium.

[Manufacture of the second type of magneto-optical recording medium]
A glass substrate was used as the transparent substrate 1 of the magneto-optical recording medium 70 shown in FIG. On one surface of the glass substrate, a transparent resin film 2 to which a preformat pattern has been transferred is formed. The dielectric film 3 is made of SiN, and is formed with a film thickness that causes the reproduction laser light to multiply interfere to increase the apparent Kerr rotation angle. Auxiliary magnetic film 8, a rare earth and made ferrimagnetic amorphous alloy GdFeCo transition metal, up to a certain critical temperature T _CR above room temperature RT represents a plane magnetic anisotropy, the perpendicular magnetic anisotropy at T _CR or Shows sex. The non-magnetic film 9 is made of SiN, and the auxiliary magnetic film 8 and the magneto-optical recording film 1
0 is inserted for magnetostatic coupling. The magneto-optical recording film 6 is made of a ferrimagnetic amorphous alloy Tb of a rare earth and a transition metal.
It is made of FeCo and has perpendicular magnetic anisotropy from room temperature to Curie temperature. The protective film 7 is made of SiN,
The protective film 7 is provided to protect the thin film laminated between the protective film 7 and the protective film 7 from chemical adverse effects such as corrosion.

The dielectric film 3, the auxiliary magnetic film 8, the non-magnetic film 9,
The magneto-optical recording film 10 and the protective film 7 were formed to have the following film thicknesses by continuous sputtering using a magnetron sputtering device. The dielectric film 3 was 60 nm, the auxiliary magnetic film 8 was 60 nm, the nonmagnetic film 9 was 20 nm, the magneto-optical recording film 10 was 50 nm, and the protective film 7 was 60 nm.

TbFeCo constituting the magneto-optical recording film 10
Is Tb ₂₁ Fe ₆₆ Co ₁₃ in atomic% ratio, and exhibits a characteristic in which the transition metal magnetization component is superior to the rare earth magnetization component from room temperature to its Curie temperature T _CO = 270 ° C. On the other hand, the composition of GdFeCo constituting the auxiliary magnetic film 8 is Gd ₂₈ Fe ₅₃ Co ₁₉ in atomic% ratio, and the single-layer film shows the temperature characteristic of the Kerr rotation angle as shown in FIG.

In FIG. 10, the horizontal axis is temperature, and the vertical axis is the ratio θ _kR / θ between the residual Kerr rotation angle θ _KR and the saturation Kerr rotation angle θ _kS of the GdFeCo auxiliary magnetic film 8 obtained from the hysteresis of the Kerr rotation angle with respect to temperature. Indicates _kS . According to this graph, the critical temperature T _{CR at} which the auxiliary magnetic film 8 changes from an in-plane magnetic film to a perpendicular magnetic film is about 20.
0 ° C. Further, the auxiliary magnetic film 8 has a Curie temperature Tc of 300 ° C. or higher, a compensation temperature T _comp between _room temperature T _room and the Curie temperature, and T _comp is about 230 ° C. The critical temperature T _CR , the compensation temperature T _{comp, the} Curie temperature Tc of the auxiliary magnetic film 8 and the Curie temperature T of the magneto-optical recording film 10.
The relationship of _CO is as follows. T _room <T _CR <T _comp <T
c ₀ <Tc. By satisfying this condition, reproduction using power-modulated pulse light described later becomes extremely easy.
Using the magneto-optical recording medium 70 having the above structure, FIG.
The reproduction method as described in the explanation of the principle of the present invention in relation to 1 is executed.

[Preliminary Experiment for Determining Reproduction Laser Pulse Intensity] In the reproduction method of the present invention, the recording magnetic domain is expanded and reproduced by using a pulse light whose laser power has been modulated to high power Pr2 and low power Pr1. For this reason, a preliminary experiment is first performed to determine the optimum laser power of Pr2 and Pr1 for reproducing data recorded on the magneto-optical recording medium 70. In this preliminary experiment, a recording / reproducing laser beam is irradiated from the substrate 1 side (the auxiliary magnetic film 8 side) using a magneto-optical drive having an optical system having a laser beam wavelength of 680 nm and a numerical aperture of 0.55. As described later, continuous laser light is used as the reproduction laser light, and the power is changed to various powers, and the reproduction signal waveform is observed.

A laser beam having a linear velocity of 5.0 m / s and a recording power of 4.5 mW is modulated on a previously initialized track of the magneto-optical recording medium 70 located at a radius of 40 mm with a period of 640 ns and a pulse width of 213 ns, thereby obtaining a recording magnetic field. Light modulation recording was performed while applying 500 Oe. Thus, recording marks having a pitch of 3.2 μm and a length of about 1.6 μm were continuously recorded on the track.

Next, the track on which the recording mark was recorded was reproduced with continuous light of various reproduction powers Pr. In order to determine the optimum modulation condition of the reproducing power, the power P of the continuous light is used.
When the value of r is Pr = 1.0 mW, 1.5 mW, 1.9 mW,
Reproduced signals were obtained in five stages of 2.0 mW and 2.1 mW, respectively. At the time of reproduction, the magneto-optical recording medium 7
Although no magnetic field was positively applied to 0, a leakage magnetic field (about 80 Oe) was generated in the recording direction from the actuator of the optical head.

At each reproduction power Pr, the magneto-optical recording medium 7
FIG. 12A shows a reproduced waveform when the recording track of No. 0 is reproduced.
To E. At this time, a trigger was applied to the reproduced waveform itself, and the waveform was observed with an oscilloscope. FIG. 12A shows a reproduction waveform when the reproduction light power Pr = 1.0 mW, and it can be seen that the reproduction signal according to the recording mark pattern rises. On the graph, the baseline indicates the erased state, and the rising peak signal indicates the recorded state. The amplitude between the recorded state and the erased state was 50 mV. When the reproducing light power is further increased to Pr = 1.5 mW, FIG.
As shown, the signal amplitude increased to about 200 mV. From the waveform of FIG. 12B, it can be seen that in some regions of the waveform, adjacent peak signals are connected on the recording state side.

FIG. 12C shows that the reproducing power is Pr = 1.9 m.
The waveform of the reproduced signal W is a waveform in which the peak signal is completely connected on the recording state side (upper part in the figure). This is because magnetic domain expansion occurs in the auxiliary magnetic film as described later,
This shows that the enlarged magnetic domain is moving on the track together with the scanning of the track by the reproduction light spot.
Further, when the reproducing light power is increased to Pr = 2.0 mW, as shown in FIG. 12D, the connected peak signal starts to be interrupted. In this case, the amplitude _Hplo between the connection of the peak signal and the _baseline was about 350 _mV .
When the reproducing light power is further increased to Pr = 2.1 mW, the peak signal is completely interrupted as shown in FIG.
It has a waveform corresponding to the recording mark pattern. In FIG. 12E, the amplitude in the recorded state and the erased state was 200 mV.

Here, the magnetization states of the magneto-optical recording film 10 laminated via the auxiliary magnetic film 8 and the non-magnetic film 9 when the reproduction waveforms of FIGS. 12A to 12E are obtained are conceptual diagrams of FIGS. This will be described with reference to FIG. FIG. 13 shows the reproduction light spot 80 when the signal waveform of FIG. 12A is obtained (reproduction light power Pr = 1.0 mW) and the directions of magnetization of the auxiliary magnetic film 8 and the magneto-optical recording film 10 to which the reproduction light spot 80 is irradiated. Shows the relationship. First, as shown in FIG. 13A, the auxiliary magnetic film 8 irradiated with the reproducing light spot 80 becomes perpendicularly magnetized in a region where the temperature rises to the critical temperature _TCR or more, and the magnetization of the magneto-optical recording film 10 is increased. Is transferred to the region 83a of the auxiliary magnetic film by the magnetostatic coupling. As shown in FIG. 13B, when the reproducing light spot 80 comes directly below the magnetic domain (recording magnetic domain) 82 whose magnetization is oriented in the recording direction, the magnetization of the recording magnetic domain 82 is transferred to the auxiliary magnetic film 8 by magnetostatic coupling. In this case, since the reproducing light power Pr is as low as 1.0 mW, the central portion of the auxiliary magnetic film 8 in the light spot 80, that is, the region 83
Only b exceeds the critical temperature T _CR , and does not increase beyond the width of the recording magnetic domain 82 in the area 83 b where the auxiliary magnetic film 8 is transferred. Therefore, the intensity of the reproduced signal is small as shown in FIG. 12A. When the reproduction light spot 80 passes through the recording magnetic domain 82, the transfer region 83c has the same magnetization direction as the magnetic domain of the magneto-optical recording film 10 immediately above by transfer from the magnetic domain of the magneto-optical recording film 10 immediately above.

FIG. 14 shows the reproduction light spot 80 when the signal waveform shown in FIG. 12C is obtained (reproduction light power Pr = 1.9 mW), and the auxiliary magnetic film 8 and the magneto-optical recording film 10 irradiated with the reproduction light spot 80. The relationship between the directions of magnetization is shown.
Increase this case, since the reproducing light power is relatively large and 1.9 mW, a spot in the entire region 85a of the auxiliary magnetic film 8 which reproducing light spot 80 is irradiated as shown in FIG. 14A is above the critical temperature T _CR As a result, the magnetization becomes perpendicular. Then, the magneto-optical recording film 10 is formed by magnetostatic coupling from the magneto-optical recording film 10.
Are transferred to the region 85a. Reproduction light spot 80
When the reproduction light spot 80 comes directly below the recording magnetic domain 82 as shown in FIG. 14B by the scanning, the magnetization of the recording magnetic domain 82 is transferred. In this case, since the width of the region 85b of the auxiliary magnetic film 8 that has risen to the critical temperature _TCR or higher is larger than that of the recording magnetic domain 82, the recording magnetic domain 82 is enlarged and transferred in the auxiliary magnetic film 8. . By this magnetic domain expansion, a large signal waveform can be obtained. Further, the reproduction light spot 80
Even after passing through the recording magnetic domain 82, the region 85c maintains the same magnetization state as that of the region 85b, so that a waveform in which the reproduced signal peaks are connected as shown in FIG. 12C is obtained.

In the case of FIG. 14, even after the reproduction light spot 80 has passed the recording magnetic domain 82, the region 85c maintains the same magnetization state as the region 85b, and is transferred to the auxiliary magnetic layer, transferred to the magnetic domain, and expanded in the magnetic domain. The recorded magnetic domain is reduced by the light spot. The reason is considered as follows. When the reproducing laser beam is irradiated, the auxiliary magnetic layer 8 is heated to a temperature higher than the critical temperature and becomes a perpendicular magnetization film, and has a coercive force Hc in the vertical direction. During reproduction, an external magnetic field Hex due to a leakage magnetic field from an actuator or the like of the optical head is applied to the auxiliary magnetic film 8.
(In this case, the recording direction, that is, downward), and a static magnetic field Hs at which the magnetization of the magneto-optical recording film 10 is generated at a temperature equal to or higher than the critical temperature of the auxiliary magnetic film 8 is applied. Its magnitude is Hex + Hs (the magnetization of the recording magnetic domain is downward) and Hex-Hs (the magnetization of the recording magnetic domain is upward) depending on the direction of magnetization of the magneto-optical recording film 10. In the relationship between the combined magnetic field of the external magnetic field Hex and the static magnetic field Hs and the magnitude of the coercive force Hc of the auxiliary magnetic film 8, the absolute value of Hc is (Hex + Hs) or (Hex).
When the absolute value is larger than (ex−Hs), the magnetization formed on the auxiliary magnetic film 8 is maintained as it is, and the magnetic domain once transferred to the auxiliary magnetic film is transferred to the magneto-optical recording film 10 as shown in FIG. Even if the reproduction spot advances to an area where no recording magnetic domain exists, re-inversion is not performed. Hc is the auxiliary magnetic film 8
Is the coercive force in the perpendicular direction in the perpendicular magnetization state. In the case of FIG. 13, Hc of the auxiliary magnetic layer is higher than that of FIG. The magnetic domain transferred to the auxiliary magnetic film 8 is re-inverted when the reproduction spot advances to a region where no recording magnetic domain exists in the magneto-optical recording film 10 (FIG. 13C).

FIG. 15 shows the reproduction light spot 80 when the signal waveform shown in FIG. 12E is obtained (reproduction light power Pr = 2.1 mW), and the auxiliary magnetic film 8 and the magneto-optical recording film 10 irradiated with the reproduction light spot 80. The relationship between the directions of magnetization is shown.
In this case, since the reproducing light power is large and 2.1 mW, the area 87a of the front portion of the spot of the auxiliary magnetic film 8 reproducing light spot 80 is irradiated shows perpendicular magnetization to rise above the critical temperature T _CR , The magnetic recording layer 10 immediately below the magnetic recording layer 10 receives the magnetic domain transfer. However, the center and the rear part in the spot are heated more than the front part and exceed the compensation temperature Tcomp of the auxiliary magnetic film 8, so that the magnetization is reversed. (The detailed reason for the magnetization reversal will be described later in a specific example of the second reproducing method). Therefore, as shown in FIG. 15A, only the front region 87a of the auxiliary magnetic film in the reproduction light spot 80 has an upward magnetization, and the center and the rear end have a downward magnetization.

Next, when the spot 80 comes directly below the recording magnetic domain 82 by the scanning of the track with the reproduction light, the magnetization of the recording magnetic domain 82 is transferred only to the relatively low temperature area 87 b in front of the auxiliary magnetic film 8. You. Therefore, magnetic domain expansion does not occur, and a large signal as in the case of FIG. The reproduction light spot 80 is the recording magnetic domain 8
After passing through the transfer region 87c, the magneto-optical recording film 1
Due to the magnetostatic coupling from zero, the magnetization in the same direction as the magnetic domain of the magneto-optical recording film 10 immediately above and the inverted magnetic domain are mixed.

In the case shown in FIG. 14 (FIG. 12C), the reproduction signal intensity increases because the magnetic domain expansion occurs in the auxiliary magnetic film 8 as described above. Then, the recording magnetic domain 82
The magnetic domain 85b enlarged from the position moves together with the reproduction light spot 80 while being enlarged. However, in FIG. 14C, when the center of the reproduction light spot 80 comes directly below the magnetic domain 84 adjacent to the recording magnetic domain 82, the magnetization of the magnetic domain 84 is reproduced by the light spot of the enlarged magnetic domain in order to reproduce the magnetization through the auxiliary magnetic layer 8. The drag phenomenon must be prevented. That is, it is necessary to erase the enlarged magnetic domain 85c of the recording magnetic domain 82, transfer the magnetization of the magnetic domain 84 to the auxiliary magnetic layer 8, and then enlarge it.

On the other hand, FIG. 13 (corresponding to FIG. 12A) and FIG.
5 (corresponding to FIG. 12E) when the reproduction power Pr is relatively small (reproduction light power Pr = 1.0).
mW) and relatively large (reproduction light power Pr = 2.
1 mW), the magnetic domain 83 b transferred from the recording magnetic domain 82 after the reproducing light spot 80 has passed the recording magnetic domain 82.
(87b) has disappeared. That is, the phenomenon of dragging the expanded magnetic domain does not occur. Therefore, as the reproduction light, the reproduction light power Pr = 1.9 mW at which the magnetic domain expansion occurs and the reproduction light power Pr = 2.1 mW (or 1.0 mW) at which the magnetic domain expansion does not occur.
mW), the magnetic domain is expanded by using pulse light that is power-modulated at the reproduction clock cycle or an integral multiple of the reproduction clock cycle, and then the center of the reproduction light spot is placed on the next recording magnetic domain from the recording magnetic domain of the magneto-optical recording film. When moved, the enlarged magnetic domains can be eliminated.

From the results of the preliminary experiment described above, the reproducing laser beam was set to Pr = 1.9 mW in FIG.
If given as pulse light intensity-modulated between r = 2.1 mW, the reproduced signal will be detected as the difference between the reproduced signal intensities obtained in FIGS. 12C and 12E. This is Figure 1
It is considered that this corresponds to 2 _pl H _pl0 = 350 _mV , and FIG.
This suggests that reproduction with a larger amplitude is possible compared to the amplitude obtained in 2A and 12E. For this reason, in a reproduction experiment using the following reproduction light pulse, a high power P
r2 = Pr2 = 2.1 mW, low power Pr1 = Pr1 =
It is set to 1.9 mW.

[First Reproducing Method of Magneto-optical Recording Medium Using Power-Modulated Pulsed Light] After initializing the magneto-optical recording medium 70 manufactured in this embodiment, a linear velocity of 5.0 m was applied to a track located at a radius of 40 mm. / S, a laser beam having a recording power of 6.3 mW was modulated with a period of 320 ns and a pulse width of 53.3 ns, and optical modulation recording was performed with a recording magnetic field of 500 Oe. This corresponds to continuously recording about 1.6 μm recording marks at a 3.2 μm pitch.

The recording track of the magneto-optical recording medium 70 thus recorded is irradiated with a pulse laser whose power has been modulated to the reproducing light laser power Pr2 = 2.1 mW and Pr1 = 1.9 mW determined in the preliminary experiment. Reproduce.
As shown in FIG. 16, the reproduction laser pulse has a pulse width of 10 ns from the front end of the recording mark and Pr2 = 2.1 m.
W, then Pr1 = 1.9 mW with 150 ns pulse width
It was adjusted to be. During reproduction, no magnetic field was positively applied, but a leakage magnetic field (about 80 Oe) was generated in the recording direction from the actuator of the optical head.

FIG. 17 shows the obtained reproduced signal waveform. A reproduced signal having an amplitude of about 220 mV was obtained corresponding to the recording mark. When the mark patterns recorded under the same conditions were reproduced with continuous light having constant reproduction powers Pr = 1.0 mW and Pr = 2.1 mW, the amplitudes were 100 mV and 170 mV, respectively. From these results, by performing power modulation of the reproduction light in a pulse shape and performing reproduction, the recording magnetic domain can be enlarged and transferred in a form synchronized with the reproduction clock, and can be erased immediately after that. C
It can be seen that reproduction can be performed at / N.

In this embodiment, the high power Pr2 = 2.1 m
Each pulse laser intensity of W and low power Pr1 = 1.9 mW was selected, and a low power pulse was used for generating an expanded magnetic domain and a high power pulse was used for disappearing an expanded magnetic domain. However, Pr2 =
1.9mW, low power pulse is used to eliminate the extended magnetic domain.
It is also possible to set r1 = 1.0 mW. The example shown in FIG. 11 used in the explanation of the principle shows the latter case. Furthermore, the ratio of the pulse width of the high power pulse to the low power pulse,
That is, the duty is not limited to the cases shown in FIGS. 11 and 16, and can be changed as appropriate to obtain an increased reproduction signal.

Also in the magneto-optical recording medium manufactured in Example 2, the temperature profile of the medium when irradiated with the reproducing light beam is made to have a desired shape, or the linear velocity dependence of the temperature profile is reduced. In order to reduce the size, a thermal control layer having an appropriate thermal conductivity may be provided on the protective film of the magneto-optical recording medium. Also, in order to obtain a better reproduction CN ratio,
The Kerr rotation angle θk is equal to or larger than θk of the auxiliary magnetic film at the maximum temperature of the medium when the reproduction light is irradiated, and the reproducing magnetic film, which is a perpendicular magnetization film at room temperature or higher, is divided into the dielectric film 3 and the auxiliary magnetic film 8. May be added between.

Example 3 [Second Example of Magneto-optical Recording Medium Using Power-Modulated Pulsed Light]
Reproducing method] In the embodiment of the reproducing method, the leakage magnetic field generated from the magnetic head at the time of reproducing is applied to the magneto-optical recording medium. In this embodiment, however, the DC magnetic field is positively applied in the same direction as the magnetization direction of the recording magnetic domain. The reproduction is performed while applying a voltage. Also in this example, reproduction was performed by modulating the laser beam intensity in order to realize enlargement and disappearance of the transfer magnetic domain.

First, the magneto-optical disk used in this embodiment will be described. As shown in FIG. 18, a magneto-optical disk 90 is composed of a SiN dielectric layer 3 and a reproducing layer (auxiliary magnetic film) made of a GdFeCo alloy on a polycarbonate substrate 1.
8, a non-magnetic SiN layer 9, a recording layer (magneto-optical recording film) 10 made of a TbFeCo alloy, and a SiN protective layer 7 are laminated. The TbFeCo recording layer 10 and the GdFeCo reproducing layer 8 are magnetostatically coupled via a nonmagnetic layer 9. G
The dFeCo reproducing layer 8 is an in-plane magnetic film at room temperature, and changes to a perpendicular magnetic film when the temperature exceeds the critical temperature Tcr. The critical temperature Tcr of the GdFeCo reproducing layer 8 used in this embodiment is 175 ° C., and the Curie temperature Tc is 340 ° C.
It is. The GdFeCo reproducing layer 8 has a critical temperature Tc
Compensation temperature Tcomp = 240 between r and Curie temperature Tc
With ° C. The TbFeCo recording layer 10 used had a Curie temperature Tco of 270 ° C. and a compensation temperature Tcomp ′ of room temperature or less. That is, Troom <Tcr <Tcomp <Tco
<Tc, and their temperature relationships are as described with reference to FIG.

When reproducing the recording signal recorded on the recording layer 10 of the magneto-optical disk 90 as described above, as described in the principle of the reproducing method of the present invention, the reproducing power is increased by the reproducing clock or its integral multiple. (Recording clock or an integral multiple thereof) to modulate to two types of power. The reduction and disappearance of the expanded magnetic domain can occur at either low power or high power as described above. In this embodiment, the reproducing light is modulated to low power for the transfer and expansion of the magnetic domain. The reproduction light for reducing or eliminating the expanded magnetic domain was modulated at high power. This power level is applied while the recording track is scanned by irradiating the magneto-optical disk with reproduction light.

As a light source for recording and reproduction, a wavelength of 680 is used.
An optical head having a nm and a lens numerical aperture of 0.55 was used. FIG.
The recording on the magneto-optical disk 90 shown in FIG. 8 was performed using an optical pulse intensity modulation method. Recording was performed at a linear velocity of 5 m / s, a recording period of 320 ns, a recording laser power of 7.5 mW, a pulse width of 53.3 ns, and a recording magnetic field of 500 Oe.
0.8 μm recording magnetic domains were recorded at 0.8 μm intervals corresponding to data such as 1 and 0. FIG. 19A shows the recorded magnetic domains together with the recording signals.

This recorded magnetic domain was reproduced under the following reproducing conditions. The linear velocity is 5.0 m / s, the reproducing laser power is 1.5 mW as low power Pr1 for magnetic domain expansion, and 3.5 as high power Pr2 for magnetic domain reduction (or disappearance).
Modulated to two power levels of mW. FIG. 19B shows the timing signal of the reproduction light power. The modulation cycle of the reproduction power was 160 ns, and irradiation was performed for 150 ns with low power Pr1 and for 10 ns with high power Pr2. As the reproducing magnetic field, a constant DC magnetic field was used, and about 80 Oe was applied in the recording direction.
This magnetic field can be substituted by the leakage magnetic field from the objective lens / actuator as in the first reproducing method (Example 2).

FIG. 19 (c) shows the reproduced waveform obtained. From the reproduced waveform, it can be seen that the signal rises only in the portion where the recording magnetic domain exists, and that the signal does not rise where the recording magnetic domain does not exist. This means that the recording magnetic domain is transferred and expanded in the reproducing layer only when the reproducing light is scanning the portion where the recording magnetic domain of the recording track exists. Further, the reproduced signal has been amplified to a magnetic super-resolution mode, that is, about 1.5 times as large as the reproduced signal when the magnetic domain transferred by the magnetic domain is reproduced without being enlarged. This effect of amplifying the reproduced signal is remarkably effective in a finer recording magnetic domain. Even when a magnetic domain of 0.4 μm or less is recorded, the saturation amplitude (the reproducing signal and the reproducing signal when all the magnetizations of the reproducing layer are directed downward) are obtained. 80% relative to the reproduction signal when all the magnetizations of the layer are upward)
(To the saturation amplitude ratio) was obtained.

The reproduction conditions of this embodiment can be explained as follows in relation to FIG. 20 used in the explanation of the principle. That is, the temperature region (areas (a) and (b)) where the magnetic domain transfer and magnetic domain expansion of FIG. 20 occur with the low power Pr1 of the power-modulated reproduction light, that is, Tcr = 175 ° C. to Tcomp
= 240 ° C., the reproducing layer is heated to a temperature region (area (c)) where the magnetic domain disappears as shown in FIG. 20 with high power Pr 2, that is, from a temperature exceeding Tcomp (240 ° C.), Tco = 270
Heated to ° C. Also, a DC magnetic field of about 80 Oe applied in the recording direction positions the magnetic temperature curves A and B in a relationship as shown in FIG. That is, the relationship between the magnetic temperature characteristics of the magneto-optical disk used in this embodiment and the applied DC magnetic field satisfies the following requirements (3) and (4). Hereinafter, requirements necessary for the reproducing method described in this embodiment will be listed. The magnetic characteristics of the reproducing layer and the recording layer of the magneto-optical recording medium used in this embodiment satisfy the following requirements (1) and (2) as described above.

(1) The reproducing layer which is magnetized at least at room temperature in the film surface direction has a compensation temperature Tcomp between the critical temperature Tcr at which magnetization is performed in the vertical direction and the Curie temperature Tco. (2) The Curie temperature Tco of the recording layer is equal to the compensation temperature T of the reproducing layer.
Be at a temperature between comp and the Curie temperature of the regeneration layer Tco. (3) Under the condition that an external magnetic field Hex is applied in the recording direction, the magnetic temperature curve A and the magnetic temperature curve B intersect between room temperature and the compensation temperature Tcomp of the reproducing layer (T1). The curve A and the magnetic temperature curve B are between the compensation temperature Tcomp of the reproducing layer and the Curie temperature Tco of the recording layer (T
Cross at 2).

In this embodiment, a magneto-optical disk is formed by using the specific material shown in FIG.
By applying Oe in the recording direction, the above requirements (1) to
Although (4) was satisfied, any material that can satisfy the requirements (1) to (4), a magneto-optical recording medium having a laminated structure, and an external magnetic field applied at the time of reproduction may be used. Can be used. The DC magnetic field applied at the time of reproduction may be not only in the recording direction but also in the erasing direction.

In the reproducing method of the present invention, by modulating the reproducing light power intensity under a DC magnetic field,
The processes of (a) magnetic domain transfer, (b) magnetic domain enlargement, and (c) disappearance of the transferred magnetic domain are performed. The time during which these processes are performed depends not only on the magnetic properties of the recording layer and the reproducing layer,
It also depends on the temperature rise rate of the recording layer, the reproducing layer, the nonmagnetic layer, the dielectric layer, the protective layer, and other stackable magnetic or nonmagnetic layers, the substrate, etc., and the heat transfer rate between the layers. These speeds can be adjusted by appropriately changing the thermal conductivity, the thickness, the laminated structure, and the like of the materials constituting the layers, and thereby can correspond to a desired reproduction access speed.

It is preferable that the dielectric layer and the nonmagnetic layer adjacent to the reproducing layer (auxiliary magnetic layer) have appropriate heat insulating properties.
The degree of heat insulation can be appropriately adjusted in relation to the access speed of recording / reproduction, or the magnitude of the linear velocity of recording / reproduction in a recording medium, and the thermal characteristics in combination with the thermal conductivity of the reproduction layer and the recording layer. it can.

In the above embodiment, the structure in which the reproducing layer (auxiliary magnetic layer) of the magneto-optical recording medium is sandwiched between the dielectric layer and the non-magnetic layer has been described. A magnetic body having inward magnetic anisotropy may be laminated. The magnetic material has a predominant in-plane magnetic anisotropy up to its Curie temperature, and it is preferable that the Curie temperature is substantially equal to the Curie temperature of the reproducing layer. By laminating such a magnetic material in contact with the reproducing layer, it is possible to suppress the occurrence of Bloch lines in the transfer magnetic domain at the time of reproducing, and to reduce the noise at the time of reproducing by the suppression action. As a material of such a magnetic body, a Pt—Co alloy, for example, a Pt—Co alloy containing 25 atomic% of Co, a GdFeCo alloy, or the like can be used. The magnetic material may be laminated on the upper side or the lower side of the reproducing layer.

In the first embodiment, an optical magnetic field modulation system in which the polarity of an applied magnetic field is modulated in accordance with a recording signal while irradiating pulse light is used. Recording was performed using the light modulation method for modulating the intensity, but any of a magnetic field modulation recording method using ordinary DC light, a light modulation recording method, and a light magnetic field modulation method may be used.

Embodiment 4 [Third Magneto-Optical Recording Medium Using Power-Modulated Pulsed Light]
In this embodiment, as in the third embodiment, reproduction is performed while a DC magnetic field is positively applied in the same direction as the magnetization direction of the recording magnetic domain. Also in this example, reproduction was performed by modulating the laser beam intensity in order to realize enlargement and disappearance of the transfer magnetic domain.

First, the magneto-optical disk used in this embodiment will be described. As shown in FIG. 23, the magneto-optical disc 100 has an SiN dielectric layer 3 on a surface of the polycarbonate substrate 1 on which the preformat pattern 2 is formed.
Reproducing layer (second auxiliary magnetic film) 2 made of GdFeCo alloy 2
4, a lamination of a SiN non-magnetic layer 29, a magnetic layer (first auxiliary magnetic film) 28 made of a GdFeCo alloy, a recording layer (magneto-optical recording film) 10 made of a TbFeCo alloy, and a SiN protective layer 7. TbFeCo recording layer 10 and GdFeCo
The reproducing layer 24 is magnetostatically coupled to the nonmagnetic layer 9 via a magnetic layer (first auxiliary magnetic film) 28 made of a GdFeCo alloy.

[0104] reproducing layer composed of GdFeCo alloy (second auxiliary magnetic layer) 24 indicates the plane magnetization at room temperature, a magnetic film which transfers to the perpendicular magnetization film at a temperature above the higher critical temperature Tcr ₁₂ than room temperature. In this embodiment, as the reproducing layer 24, G
d ₂₈ Fe ₅₆ Co ₁₆ is used, is an in-plane magnetic film at room temperature, and changes to a perpendicular magnetic film at a temperature exceeding the critical temperature Tcr ₁₂ = 175 ° C. The Curie temperature T of the reproducing layer 24
c ₂ is 340 ° C.

The magnetic layer (first auxiliary magnetic layer) 28 made of a GdFeCo alloy is a magnetic film that exhibits perpendicular magnetization at room temperature and transfers to an in-plane magnetized film at a temperature above a critical temperature Tcr ₁₁ higher than room temperature. . In this embodiment, Gd ₂₁ Fe ₆₄ Co ₁₅ is used as the magnetic layer 28 made of a GdFeCo alloy, is a perpendicular magnetization film at room temperature, and has a critical temperature Tcr ₁₁ = 20.
If the temperature exceeds 0 ° C., the film changes to an in-plane magnetized film. This magnetic layer 2
The Curie temperature Tc1 of _No. 8 was 350 ° C.

The recording layer 10 has a Curie temperature Tco of 2
A TbFeCo alloy having a temperature of 70 ° C. and a compensation temperature of room temperature or less was used. That is, between the Curie temperature Tco of the recording layer 10, the Curie temperature Tc ₂ and the critical temperature Tcr ₁₂ of the reproducing layer 24, the Curie temperature Tc ₁ and the critical temperature Tcr ₁₁ of the magnetic layer 28 (the first auxiliary magnetic film) , Room temperature <Tcr ₁₂ <Tcr ₁₁ <T
The relationship of c, Tc ₁ and Tc ₂ is established. FIG. 24 shows this temperature relationship. FIG. 24 shows the recording layer 10, the reproducing layer 24, and the magnetic layer 28 ( First auxiliary magnetic film)
Shows the magnetic properties of As shown, the temperature range in which the reproducing layer 24 and the magnetic layer 28 (first auxiliary magnetic film) exhibit perpendicular magnetization overlaps in a relatively narrow temperature range (arrow in the figure). In this temperature range, the recording layer 10 and the magnetic layer 28 can be magnetically coupled with the reproducing layer 24.

The principle of reproduction of the magneto-optical disk 100 shown in FIG. 23 is as described above with reference to FIG. That is, the reproducing layer 24 of the magneto-optical disk 100 is irradiated with the reproducing light, the temperature of the reproducing layer 24 rises, and the critical temperature Tcr ₁₂
Is transferred from the in-plane magnetization to the perpendicular magnetization, and the magnetization of the recording layer 10 is transferred to the reproducing layer 24 by the magnetostatic coupling force. Here, since the reproducing light power and Tcr ₁₂ are adjusted so that the region exceeding the critical temperature Tcr ₁₂ becomes larger than the magnetic domain of the recording layer 10 where the magnetization information is recorded, the perpendicular magnetization of the reproducing layer 24 is reduced. The portion that has it is larger than the magnetic domain of the recording layer 10 that is the transfer source (see FIG. 25C). On the other hand, the critical temperature T which is present inside the region above the critical temperature Tcr ₁₂ by the temperature distribution of the magneto-optical disc 100
In the region exceeding cr ₁₁ , the perpendicular magnetization of the magnetic layer 28 has changed to in-plane magnetization. The in-plane magnetization region of the magnetic layer 28 is the recording layer 1
The leakage magnetic field from 0 to the reproducing layer 24, particularly in the non-recording direction, is cut off. Therefore, the expansion of the reproduction layer 24 is promoted, and at the same time, the C / C of the reproduction signal from the reproduction layer 24 is increased.
N is improved. In the present invention, it is required that Tcr ₁₂ <Tcr ₁₁ is satisfied, but the temperature difference ΔT between Tcr ₁₂ and Tcr ₁₁ is required.
Is preferably selected such that the reproduction signal C / N becomes the best and the reproduction signal intensity due to the magnetic domain expansion becomes the maximum.

When reproducing the recording signal recorded on the recording layer 10 of the magneto-optical disk 100 as described above, as described in the principle of the reproducing method of the present invention, the reproducing power is increased by the reproducing clock or its integral multiple. (Recording clock or an integral multiple thereof) to modulate to two types of power. The reduction and disappearance of the expanded magnetic domain can occur at either low power or high power as described above. In this embodiment, the reproducing light is modulated to low power for the transfer and expansion of the magnetic domain. The reproduction light for reducing or eliminating the expanded magnetic domain was modulated at high power. This power level is applied while the recording track is scanned by irradiating the magneto-optical disk with reproduction light.

In the structure of the magneto-optical disk 100 shown in FIG. 23, a heat diffusion layer may be formed between the non-magnetic layer 29 and the first auxiliary magnetic layer. This heat diffusion layer functions to promote the expansion of the magnetic domain by diffusing the heat accumulated between the nonmagnetic layer 26 and the first auxiliary magnetic layer 28 in the in-plane direction of the film. Al, AlTi, Al as thermal diffusion layer
A material having high thermal conductivity such as Cr, Ag, Au, or Cu can be used.

[0110]

In the present invention, a magneto-optical recording film is a perpendicular magnetization film at room temperature over a magneto-optical recording medium, vertically and T _CR than in-plane magnetization film to a critical temperature (T _CR) of from room temperature Since one or more auxiliary magnetic films serving as magnetic films were used and the magnetic characteristics of the magnetic films were adjusted to have a predetermined relationship,
By using this magneto-optical recording medium, it is possible to reproduce the data by enlarging the recording magnetic domain, and it is possible to obtain a good C / N by increasing the reproduction signal intensity.

According to the reproducing method of the magneto-optical recording medium of the present invention, is the decrease in the amount of light contributing to the reproduction output by the magnetic mask small compared to the magnetic super-resolution type magneto-optical recording medium having a normal mask function? Alternatively, super-resolution reproduction without a decrease in light quantity can be performed. By using the magneto-optical recording medium and the reproducing method of the present invention, a recording mark extremely small as compared with the reproducing light spot diameter can be reproduced independently, so that the recording density of the magneto-optical recording medium can be significantly improved. Can be. Further, since the magnetic domain expansion reproduction is used, the reproduction signal can be amplified, and the C / N of the reproduction signal can be greatly improved.

According to the reproducing method of the present invention, the magnetic domain transfer, the expansion of the transferred magnetic domain, and the disappearance of the enlarged magnetic domain can be reliably performed by optically modulating the reproducing light power. This is a very useful way to Further, the magnetic field applied at the time of reproduction is a DC magnetic field, and it is not necessary to use an alternating magnetic field.

The magneto-optical recording medium of the present invention has a Curie temperature Tcoc of the magneto-optical recording film and a Curie temperature Tc of the auxiliary magnetic film.
And room temperature <Tcr <Tcomp <T
Under the condition that the relationship co <Tc is established and the external magnetic field Hex is applied to the magneto-optical recording medium, the temperature curve A of the external magnetic field Hex and the transfer magnetic field generated from the magneto-optical recording film and the temperature curve of the perpendicular coercive force of the auxiliary magnetic film. B intersects between room temperature and the compensation temperature Tcomp of the auxiliary magnetic film, and the temperature curve A and the temperature curve B correspond to the compensation temperature Tco of the auxiliary magnetic film.
Since it is configured to intersect between mp and the Curie temperature Tco of the magneto-optical recording film, when reproduction is performed under a DC external external magnetic field using power-modulated reproduction light,
i) transfer of magnetic domains from the magneto-optical recording film to the auxiliary magnetic film, ii)
The process of enlarging the transfer domain and iii) eliminating the enlarged domain can be reliably performed. Therefore, by using this magneto-optical recording medium, after recording a minute magnetic domain smaller than the reproducing light spot as a recording signal, the minute magnetic domain can be distinguished from other magnetic domains and detected by the amplified reproducing signal. Therefore, the magneto-optical recording medium of the present invention is extremely useful as a high-density magneto-optical recording medium.

The magneto-optical recording medium of the present invention has a critical temperature Tcr.
_In order to simultaneously provide a first auxiliary magnetic layer that transitions from a perpendicular magnetization film to an in-plane magnetization film in a region exceeding ₁₁ and a second auxiliary magnetic layer that transitions from in-plane magnetization to perpendicular magnetization at a temperature exceeding the critical temperature Tcr ₁₂ , While the first auxiliary magnetic layer blocks the leakage magnetic field from the recording layer to the second auxiliary magnetic layer, the second auxiliary magnetic layer controls the recording layer 1
Magnetization information of 0 can be reproduced by being enlarged. Therefore, the signal intensity reproduced from the second auxiliary magnetic layer is increased, and the C / N of the reproduced signal is improved.

[Brief description of the drawings]

FIG. 1 is a sectional view conceptually showing a laminated structure of a magneto-optical recording medium belonging to a first type of the present invention.

FIG. 2 is a conceptual diagram (A) showing a magnetization state of each layer before reproduction of a magneto-optical recording medium belonging to the first type of the present invention.
FIG. 3B is a conceptual diagram (B) showing the magnetization state of each layer during reproduction of the magneto-optical recording medium.

FIG. 3 is a diagram showing magnetic properties of an auxiliary magnetic film constituting the magneto-optical recording medium of the present invention.

FIG. 4 is a reproduction C / N ratio of the magneto-optical recording medium manufactured in Example 1 of the present invention and a conventional magneto-optical recording medium.
6 is a graph showing a relationship between the recording mark length and the recording mark length.

FIG. 5 is a sectional view (A) showing a laminated structure of a conventional magneto-optical recording medium and a sectional view (B) showing a laminated structure of a magnetic super-resolution magneto-optical recording medium.

FIG. 6 is a conceptual diagram (A) showing a magnetization state of each layer before reproduction of a magneto-optical recording medium belonging to the second type of the present invention.
FIG. 3B is a conceptual diagram (B) showing the magnetization state of each layer during reproduction of the magneto-optical recording medium.

FIG. 7 is a diagram conceptually showing a laminated structure of a magneto-optical recording medium belonging to a second type of the present invention.

FIG. 8 is a graph showing a temperature profile of a reading section when reproducing light is irradiated to the first type of magneto-optical recording medium of the present invention.

FIG. 9 is a graph showing the temperature and coercive force profiles of the auxiliary magnetic film and the magnetization profile of the magneto-optical recording film of the second type of magneto-optical recording medium of the present invention.

FIG. 10 is a graph showing the temperature characteristic of the Kerr effect of the auxiliary magnetic film of the magneto-optical recording medium manufactured in Example 2 of the present invention.

FIG. 11 is a timing chart for explaining the principle of a reproducing method for a magneto-optical recording medium according to the present invention.

12A to 12E are graphs showing reproduction signal waveforms observed on an oscilloscope when reproducing the magneto-optical recording medium of Example 2 of the present invention with continuous light having various reproduction powers.

13A to 13C are conceptual diagrams illustrating the magnetization state of each layer of the magneto-optical recording medium when the signal waveform shown in FIG. 12A is obtained.

14A to 14C are conceptual diagrams illustrating the magnetization state of each layer of the magneto-optical recording medium when the signal waveform shown in FIG. 12C is obtained.

15A to 15C are conceptual diagrams illustrating the magnetization state of each layer of the magneto-optical recording medium when the signal waveform shown in FIG. 12E is obtained.

FIG. 16 is a diagram showing the irradiation timing of the recording pulse of the reproducing pulse light modulated with the reproducing powers Pr1 and Pr2 determined in the preliminary experiment of the second embodiment.

FIG. 17 is a graph showing a reproduced signal waveform obtained by performing reproduction using the reproduction pulse light shown in FIG. 16;

FIG. 18 is a diagram conceptually showing a laminated structure of a magneto-optical recording medium used in a second reproducing method of the present invention.

FIG. 19 is a timing chart for explaining the principle of the method of reproducing a magneto-optical recording medium according to the present invention.

FIG. 20 is a diagram showing the magnetic temperature characteristics of the magneto-optical recording layer and the magneto-optical reproducing layer of the magneto-optical recording medium of the present invention.

FIG. 21 is a diagram illustrating a process of reproducing a recording magnetic domain of the magneto-optical recording layer from the magneto-optical reproducing layer by irradiating the magneto-optical recording medium of the present invention with a light-modulated reproducing light; (A) shows the direction of the magnetic domain of the recording layer and the reproducing layer, and (b) shows the reproduced light power modulated.

22A and 22B are diagrams for explaining the principle of magnetic domain annihilation. FIG. 22A shows the sub-lattice magnetization of the reproducing layer below the compensation temperature, and FIG. 22B shows the sub-lattice magnetization of the reproducing layer above the compensation temperature. 2 shows lattice magnetization.

FIG. 23 is a diagram showing a laminated structure of a magneto-optical recording medium manufactured in Example 4 of the present invention.

FIG. 24 is a diagram showing the magnetization characteristics of the magneto-optical recording layer, the first auxiliary magnetic layer, and the first auxiliary magnetic layer of the magneto-optical recording medium manufactured in Example 4 of the present invention.

FIGS. 25A and 25B are diagrams for explaining the principle of reproduction of the magneto-optical recording medium manufactured in Example 4 of the present invention, wherein FIG. 25A shows a state before irradiation with reproduction light, and FIG. In the process, a state where the magnetization of the recording layer is transferred to the second auxiliary magnetic layer is shown, and (c) shows a state where the magnetic domain transferred to the second auxiliary magnetic layer is enlarged.

FIG. 26 is a diagram showing the relationship between the magnetization state and the temperature distribution of the medium shown in FIG. 25 (c).

[Explanation of symbols]

 Reference Signs List 1 substrate 3 dielectric film 4 second auxiliary magnetic film 5 first auxiliary magnetic film 6 magneto-optical recording medium 8 auxiliary magnetic film (reproducing layer) 10 magneto-optical recording film 80 reproducing light spot 82 recording magnetic domain 85b enlarged magnetic domain 90, 100 light Magnetic recording medium 201a Transfer magnetic domain 201b Expanded magnetic domain 201c Disappearing magnetic domain 210 Recording magnetic domain

Continuing from the front page (72) Inventor Hiroki Takao 1-1-88 Ushitora, Ibaraki-shi, Osaka Hitachi Maxell, Inc. (72) Inventor Norio Ota 1-188 Ushitora, Ibaraki-shi, Osaka Hitachi Maxell shares In company

Claims (20)

[Claims] 1. A magneto-optical recording device for reproducing a recorded signal by irradiating a reproducing light to a magneto-optical recording medium having a magneto-optical recording film which is a perpendicular magnetization film at room temperature and detecting a magnitude of a magneto-optical effect. In the method of reproducing a medium, as the magneto-optical recording medium, a first auxiliary magnetic film and a second auxiliary magnetic film are sequentially laminated on a magneto-optical recording film, and the first auxiliary magnetic film and the second auxiliary magnetic film have a critical temperature. A magnetic film that transitions from an in-plane magnetic film to a perpendicular magnetic film when the magnetic film exceeds the above, wherein the magneto-optical recording film, the first auxiliary magnetic film, and the second auxiliary magnetic film are the magneto-optical recording film, the first auxiliary magnetic film, The Curie temperatures of the second auxiliary magnetic film are T _co , T _c1 and T _c2 , respectively.
When the critical temperatures of the first auxiliary magnetic film and the second auxiliary magnetic film are T _CR1 and T _CR2 , respectively, room temperature <T _CR2 <
Using a magneto-optical recording medium having magnetic characteristics satisfying the relationship of T _CR1 <T _CO , T _C1 , and T _C2 , reproducing the power on the magneto-optical recording medium at the same period as the reproduction clock or at a period of an integral multiple of the reproduction clock. A reproducing method for a magneto-optical recording medium, comprising reproducing a recording signal by irradiating light. Wherein said reproducing light, reproduction are power modulation to the reproducing light power Pr ₁ and Pr ₂ clock the same period or an integral multiple of the cycle, one of the reproducing light power of the Pr ₁ and Pr ₂ are the 2. The reproducing method for a magneto-optical recording medium according to claim 1, wherein the reproducing optical power is a power for causing magnetic domain expansion of the second auxiliary magnetic film. 3. Magneto-optical recording for reproducing a recorded signal by irradiating a magneto-optical recording medium having a magneto-optical recording film which is a perpendicular magnetic film at room temperature with a reproducing light and detecting a magnitude of a magneto-optical effect. In the method for reproducing a medium, as the magneto-optical recording medium, an auxiliary magnetic film that changes from an in-plane magnetic film to a perpendicular magnetic film when a critical temperature is exceeded is provided on the magneto-optical recording film via a non-magnetic film. When the Curie temperatures of the magneto-optical recording film and the auxiliary magnetic film are T _CO and T _C , respectively, and the critical temperatures of the auxiliary magnetic film are T _CR , respectively, the room temperature <T _CR < By using a magneto-optical recording medium having magnetic properties satisfying the relationship of T _CO , T _C , by irradiating the magneto-optical recording medium with reproduction light whose power has been modulated in the same cycle as the reproduction clock or in a cycle of an integral multiple of the reproduction clock. Recording signal The method of reproducing a magneto-optical recording medium, characterized in that play. Wherein said reproducing light, reproduction are power modulation to the reproducing light power Pr ₁ and Pr ₂ clock the same period or an integral multiple of the cycle, one of the reproducing light power of the Pr ₁ and Pr ₂ are the 4. The reproducing method for a magneto-optical recording medium according to claim 3, wherein the power is a power that causes magnetic domain expansion of the auxiliary magnetic film. 5. The reproducing method for a magneto-optical recording medium according to claim 1, wherein a DC magnetic field in a recording direction is applied during reproduction. 6. A reproducing method of a magneto-optical recording medium for reproducing a recorded signal by irradiating a reproducing light to the magneto-optical recording medium and detecting a magnitude of a magneto-optical effect, wherein: A magneto-optical recording film having perpendicular magnetization, and an auxiliary magnetic film that transitions from an in-plane magnetization film to a perpendicular magnetization film when the critical temperature Tcr is exceeded, via a non-magnetic film;
Between the Curie temperature Tco of the magneto-optical recording film and the Curie temperature Tc and the compensation temperature Tcomp of the auxiliary magnetic film, room temperature <
Using a magneto-optical recording medium having magnetic characteristics satisfying the relationship of Tcr <Tcomp <Tco <Tc, applying a DC magnetic field to the magneto-optical recording medium, at least two times at the same cycle as the reproduction clock or at a cycle of an integral multiple.
By irradiating reproduction light whose power has been modulated to the various optical powers Pr ₁ and Pr ₂ , the recording magnetic domain of the magneto-optical recording film is transferred to the auxiliary magnetic film, the transfer is enlarged, and the enlarged magnetic domain is reduced or A method for reproducing a magneto-optical recording medium, wherein the reproduction of a recording signal is performed through a step of extinguishing. 7. The optical power Pr1 of the reproduction light is a power for heating the auxiliary magnetic film to a temperature of Tcr to Tcomp to transfer a recording magnetic domain of the magneto-optical recording film to the auxiliary magnetic film and expand the magnetic domain. 7. The reproduction of the magneto-optical recording medium according to claim 6, wherein the optical power Pr2 of the reproduction light is a power for heating the auxiliary magnetic film to a temperature of Tcomp to Tco to reduce or eliminate the enlarged magnetic domain. Method. 8. Under a condition in which an external magnetic field Hex is applied to a magneto-optical recording medium, a temperature curve A of a transfer magnetic field generated from the external magnetic field Hex and the magneto-optical recording film and a temperature curve B of a perpendicular coercive force of the auxiliary magnetic film are different from each other. , Room temperature and the compensation temperature T of the auxiliary magnetic film
and the temperature curve A and the temperature curve B intersect between the compensation temperature Tcomp of the auxiliary magnetic film and the Curie temperature Tco of the magneto-optical recording film. 8. The method according to claim 6, wherein
3. The reproducing method for a magneto-optical recording medium according to item 1. 9. The transfer magnetic field is the sum of the static magnetic field Ht from the magneto-optical recording film and the external magnetic field Hex, and the vertical coercive force of the auxiliary magnetic film is set to the vertical coercive force Hr of the magnetic domain to be transferred. 9. The reproducing method for a magneto-optical recording medium according to claim 8, wherein the transfer magnetic domain is an exchange coupling force Hw received from an adjacent magnetic domain. 10. A magneto-optical recording medium having at least a magneto-optical recording film on a substrate, comprising: a magneto-optical recording film having a perpendicular magnetization; and an auxiliary magnetic material which transitions from an in-plane magnetization film to a perpendicular magnetization film when the critical temperature Tcr is exceeded. And a film with a non-magnetic film interposed therebetween, and a relationship that room temperature <Tcr <Tcomp <Tco <Tc between the Curie temperature Tco of the magneto-optical recording film and the Curie temperature Tc and the compensation temperature Tcomp of the auxiliary magnetic film. Under the condition that the external magnetic field Hex is applied to the magneto-optical recording medium, the temperature curve A of the external magnetic field Hex and the transfer magnetic field generated from the magneto-optical recording film and the temperature curve B of the perpendicular coercive force of the auxiliary magnetic film are: together intersect at temperatures T ₁ between the compensation temperature Tcomp room temperature and the auxiliary magnetic film, and the temperature curve a and the temperature curve B is the compensation temperature Tcomp and the magneto-optical recording film of the auxiliary magnetic film Curie - With temperature Tco The magneto-optical recording medium, characterized in that intersect at temperature T ₂ between. 11. A method in which, while applying a DC magnetic field, reproduction light whose power has been modulated to at least two types of optical powers Pr ₁ and Pr ₂ at the same period as the reproduction clock or at a period of an integral multiple of the reproduction clock is applied. 11. The magneto-optical recording medium according to claim 10, wherein a recording signal is reproduced through a step of transferring a recording magnetic domain of the magnetic recording film to the auxiliary magnetic film, expanding the magnetic domain, and reducing or eliminating the magnetic domain. 12. The optical power Pr1 of the reproduction light is a power for heating the auxiliary magnetic film to a temperature of Tcr to Tcomp to magnetically transfer and magnetically expand a recording magnetic domain of the magneto-optical recording film on the auxiliary magnetic film. 12. The optical power Pr2 of reproducing light is a power for heating the auxiliary magnetic film to a temperature of Tcomp to Tco to reduce or eliminate magnetic domains transferred and expanded on the auxiliary magnetic film. Magneto-optical recording medium. 13. The temperature according to claim 10, wherein the temperature T _{2 at} which the temperature curve A and the temperature curve B intersect is a temperature close to the compensation temperature Tcomp of the auxiliary magnetic film. Item 13. A magneto-optical recording medium according to item 1. 14. A magneto-optical recording medium having at least a magneto-optical recording film on a substrate, comprising: a first auxiliary magnetic film that changes from a perpendicular magnetization film to an in-plane magnetization film when the critical temperature Tcr ₁₁ is exceeded; _A magneto-optical recording medium, comprising: a second auxiliary magnetic film that changes from an in-plane magnetic film to a perpendicular magnetic film when the number exceeds ₁₂ . 15. The critical temperature Tcr ₁₁ of the first auxiliary magnetic film.
Magneto-optical recording medium according to claim 14, characterized in that above the critical temperature Tcr ₁₂ of the second auxiliary magnetic film. 16. A semiconductor device comprising: a magneto-optical recording film having perpendicular magnetization, the first auxiliary magnetic film, a non-magnetic film, and the second auxiliary magnetic film provided in this order on a substrate. The magneto-optical recording medium according to claim 14. 17. The magneto-optical recording medium according to claim 16, wherein the magnetization of the magneto-optical recording film is enlarged and transferred to the second auxiliary magnetic film when irradiating the reproducing light. 18. A Curie temperature Tco of a magneto-optical recording film,
Room temperature <Tcr ₁₂ <Tcr ₁₁ <T between the Curie temperature Tc ₁ and the critical temperature Tcr ₁₁ of the first auxiliary magnetic film and the Curie temperature Tc ₂ and the critical temperature Tcr _{12 of} the second auxiliary magnetic film.
co, Tc _1, the magneto-optical recording medium according to any one of claims 14 to 17 Tc ₂ at which relationship is characterized in that hold. 19. The recording of the magneto-optical recording film is performed by irradiating a reproduction light whose power is modulated to at least two kinds of optical powers Pr ₁ and Pr ₂ at a cycle based on a reproduction clock while applying a DC magnetic field. 2. The recorded signal is reproduced through a step of transferring a magnetic domain to the second auxiliary magnetic film, expanding the magnetic domain, and reducing or eliminating the magnetic domain.
19. The magneto-optical recording medium according to any one of 4 to 18. 20. A magnetic domain having in-plane magnetization in the first auxiliary magnetic layer is larger than a recording magnetic domain to be reproduced and a magnetic domain having perpendicular magnetization in the second auxiliary magnetic layer is irradiated with the reproducing light when the reproducing light is irradiated.
20. The magneto-optical recording medium according to claim 14, wherein the magnetic domain is larger than a magnetic domain having in-plane magnetization in the auxiliary magnetic layer.