JP2521908C - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]   The present invention relates to a magneto-optical recording method, a magneto-optical recording device used in the method, and magneto-optical recording.
It relates to a recording medium. In particular, the present invention relates to a magneto-optical recording capable of overwriting.
Recording method, overwritable magneto-optical recording apparatus, and overwritable recording medium
About the body. [Conventional technology]   Recently, including high density, large capacity, high access speed, and high recording and playback speed
Optical recording and reproducing method that satisfies the various requirements
Efforts have been made to develop raw devices and recording media.   Among a wide range of optical recording / reproducing methods, magneto-optical recording / reproducing methods use information.
Unique information that can be erased and record new information later
Filled with the greatest attraction for the benefit Is   The recording medium used in this magneto-optical recording / reproducing method has one or more recording / reproducing layers.
It has a multilayer perpendicular magnetic film (perpendicular magnetic layer or layers). This magnet
For example, amorphous GdFe, GdCo, GdFeCo, TbFe, TbCo, TbFeCo, etc.
Become. The recording layer generally forms a concentric or spiral track.
Information is recorded on the rack. Here, in this specification, “upward (
upward) ”or“ downward ”,“ A direction ”, the other“ reverse ”
A direction ". The information to be recorded is binarized in advance, and this information is referred to as “
Bit having magnetization in the “A direction” (B₁) And a bit having "reverse A direction" magnetization
(B₀) Are recorded by two signals. These bits B₁, B₀Is a digital signal
1 and 0 correspond to the other and the other, respectively. But generally recorded
Track magnetization is strong before recording By applying an appropriate external magnetic field, it is aligned in the “reverse A direction”. This process is initial
It is called initialization. Then, a bit having “A direction” magnetization is applied to the track.
G (B₁) Is formed. Information is stored in this bit (B₁) And / or bit length
Therefore, it is recorded.Principle of bit formation :   In the formation of the bit, the characteristic of the laser, that is, a spontaneous aggregation in space and time
Diffraction limit determined by the wavelength of the laser light, where coherence is advantageously used
The beam is narrowed to a spot that is as small as the field. Narrowed light
Is irradiated on the track surface to form a bit having a diameter of 1 μm or less on the recording / reproducing layer.
Thus, information is recorded. In optical recording, theoretically about 10⁸Bit / c
m^TwoRecording density up to Because the laser beam is
With the chief Concentrate to a spot of approximately the same small diameter.
Because it can do.   As shown in FIG. 1, in magneto-optical recording, the laser beam (L) is re-recorded.
Squeeze on the green layer (1) and heat it. During this time, the
A pair of recording magnetic fields (Hb) are externally applied to the heated portion. Then the station
The coercive force Hc (coersivity) of the partially heated portion decreases and becomes smaller than the recording magnetic field (Hb).
It becomes. As a result, the magnetization of that portion is aligned in the direction of the recording magnetic field (Hb). In this way
Conversely, a magnetized bit is formed.   Ferromagnetic materials and ferrimagnetic materials have different magnetization and temperature dependence of Hc.
Ferromagnetic materials have a decreasing Hc near the Curie point.
The recording is performed. Therefore, it is referred to as Tc writing (Curie point writing).   On the other hand, ferrimagnetic materials have a compensation temperat
ure), where the magnetization (M) goes to zero. Conversely, around this temperature, Hc
Becomes extremely large, and when it deviates from the temperature, Hc drops sharply. This drop
Hc is defeated by the relatively weak recording magnetic field (Hb). In other words, the record
Will be possible. This recording process is called T_comp. This is called writing (compensation point writing).   However, it is not necessary to stick to the Curie point or its vicinity and the vicinity of the compensation temperature.
No. In short, a magnetic material having a reduced Hc at a predetermined temperature higher than room temperature
When a recording magnetic field (Hb) that defeats the lowered Hc is applied to the recording material,
Recording is possible.The principle of reproduction :   FIG. 2 shows the principle of information reproduction based on the magneto-optical effect. The light is flat perpendicular to the optical path.
All directions on the surface Is an electromagnetic wave having a diverging electromagnetic field vector. If the light is linearly polarized (L
_p) And irradiates the recording / reproducing layer (1), light is reflected on its surface.
Or through the recording / reproducing layer (1). At this time, the polarization plane is
Rotate according to direction. This rotating phenomenon is caused by the magnetic Kerr effect or the magnetic
Called the Faraday effect.   For example, if the plane of polarization of the reflected light rotates θk degrees with respect to the “A-direction” magnetization,
Then, for the "reverse A direction" magnetization, the rotation is -.theta.k degrees. Therefore, the optical analyzer
If the (polarizer) axis is set perpendicular to the plane inclined -θk degrees,
Magnetized bit (B₀) Can be transmitted through the analyzer
Absent. On the other hand, the bit (B₁The light reflected from) is (
sin2θk)^TwoMultiplied by the light penetrates the analyzer, and the detector (photoelectric conversion means)
Captured by It is. As a result, the bit (B₁) Is magnetized in the "reverse A direction"
Bit (B₀) Looks brighter and produces a strong electrical signal at the detector
Let it. The electrical signal from this detector is modulated according to the recorded information
Therefore, the information is reproduced. [Problems to be solved by the invention]   By the way, in order to reuse a recorded medium, (i) the medium is initialized again by the initialization device.
Initialize or (ii) equip the recording device with an erase head similar to the recording head
Or (iii) recorded in advance using a recording device or an erasing device as pre-processing.
Information needs to be erased.   Therefore, in the magneto-optical recording method, a new method has been used regardless of the presence or absence of recorded information.
It was impossible to overwrite the information on the spot.   However, if the direction of the recording magnetic field (Hb) is changed to "A direction" and "
Overwriting becomes possible if it can be changed freely. However
However, it is impossible to change the direction of the recording magnetic field (Hb) at a high speed. For example
When the recording magnetic field (Hb) applying means is a permanent magnet, the direction of the magnet is mechanically reversed.
Need to be turned over. However, it is impossible to reverse the direction of the magnet at high speed.
You. Even when the recording magnetic field (Hb) applying means is an electromagnet, the direction of the large current is changed.
It is impossible to change at such a high speed.   Therefore, a first object of the present invention is to modulate light without changing the direction of the recording magnetic field (Hb).
To provide an overwritable magneto-optical recording method.   A second object is to provide an overwritable magneto-optical recording device.
is there.   A third object is to provide an overwritable magneto-optical recording medium. [Means for solving the problem]   According to the present invention, first, information is upwardly magnetized with respect to a recording / reproducing layer of a magneto-optical recording medium.
Magneto-Optical Recording Method with Bits with Downward Magnetization and Bits with Downward Magnetization
,   The method is (a) As the medium, the first layer having perpendicular magnetic anisotropy is used as a recording / reproducing layer,
Using a multi-layer magneto-optical recording medium having a second auxiliary layer as a recording auxiliary layer; (b) moving the medium; (c) Only the magnetization of the recording auxiliary layer, before recording Be aligned either upwards or downwards; (d) irradiating the medium with a laser beam; (e) modulating the beam intensity in a pulse form according to the binary information to be recorded; (f) applying a recording magnetic field to the medium portion irradiated with the beam; (g) when the beam intensity is at a high level, the bit having an upward magnetization and the
To form one of the bits having a low beam intensity.
When the other bit is formed; And providing an overwritable method comprising:   Second, the present invention relates to a magneto-optical recording device, (a) means for moving the magneto-optical recording medium; (b) means for applying an initial auxiliary magnetic field; (c) laser beam light source; (d) beam intensity according to the binary information to be recorded,   (1) Either a bit having an upward magnetization or a bit having a downward magnetization
A high level that gives the medium the temperature necessary to form a bit of   And (2) a low level that gives the medium the temperature needed to form the other bit.
Means for modulating in a pulsed manner; (e) a recording magnetic field applying means that may also be used as the initial auxiliary magnetic field applying means; And a device capable of overwriting.   Third, the present invention relates to a magneto-optical recording device, (a) means for moving the magneto-optical recording medium; (b) laser beam light source; (c) beam intensity according to the binary information to be recorded,   (1) Either a bit having an upward magnetization or a bit having a downward magnetization
A high level that gives the medium the temperature necessary to form a bit of   And (2) a low level that gives the medium the temperature needed to form the other bit.
Modulate in pulse form Means; (d) magnetic field applying means; And a device capable of overwriting.   Fourth, according to the present invention, the first layer having perpendicular magnetic anisotropy is used as a recording / reproducing layer,
Overwritable multilayer magneto-optical recording using a second layer having gas anisotropy as a recording auxiliary layer
Provide recording media.   Fifth, the present invention provides a first layer having perpendicular magnetic anisotropy as a recording / reproducing layer,
A second layer having perpendicular magnetic anisotropy as a recording auxiliary layer and at least two layers,
Both layers are magnetically coupled, so that the magnetization direction of the second layer is
Overwrite that can be aligned either upwards or downwards
A possible multilayer magneto-optical recording medium is provided.   Sixth, the present invention relates to a magneto-optical recording device, (a) The first layer having perpendicular magnetic anisotropy is used as a recording / reproducing layer and has perpendicular magnetic anisotropy.
Record the second layer The auxiliary layer is used to move a multilayer magneto-optical recording medium in which the Curie point of the second layer is higher than that of the first layer.
Means to make; (b) laser beam light source; (c) According to the binary information to be recorded, the beam intensity is   (1) a high level that raises the temperature of the medium to near the Curie point of the second layer;
Pulse modulation between a low level which raises the temperature of the recording medium near the Curie point of the first layer
Means to do; (d) magnetic field applying means; An apparatus characterized by comprising:   Seventh, according to the present invention, the first layer having perpendicular magnetic anisotropy is used as a recording / reproducing layer,
The second layer having gas anisotropy is used as a recording auxiliary layer, and the Curie point of the second layer is higher than that of the first layer.
When there is a large multilayer magneto-optical recording medium,   (1) a high level that raises the temperature of the medium to near the Curie point of the second layer;
Between the low level, which raises the temperature of the recording medium to near the Curie point of the first layer,
A modulation device for pulse-modulating a beam intensity is provided.   Eighth, the present invention provides (1) a video having an upward magnetization. Necessary to form one of two bits, a bit with a lower magnetization and a lower magnetization
High level to apply a high temperature to the magneto-optical recording medium and (2) forming the other bit
Modulates the laser beam between low levels, which gives the medium the required temperature
Provide a way to   Ninth, according to the present invention, the first layer having perpendicular magnetic anisotropy is used as a recording / reproducing layer,
The second layer having gas anisotropy is used as a recording auxiliary layer, and the Curie point of the second layer is higher than that of the first layer.
When there is a large multilayer magneto-optical recording medium,   (1) a high level that raises the temperature of the medium to near the Curie point of the second layer;
Between the low level, which raises the temperature of the recording medium to near the Curie point of the first layer,
A method is provided for pulse modulating the beam intensity.   Tenth, the present invention comprises at least two layers, a recording / reproducing layer and a recording auxiliary layer.
When irradiated with a laser beam, the “A direction” magnetization of the recording auxiliary layer
Bits having "A direction" magnetization or "reverse A direction" magnetization are formed in the recording / reproducing layer.
Record Provide recording media.   Eleventh, the present invention comprises at least a first layer and a second layer laminated thereon,Provide a medium that satisfies Where H_C1Is the coercive force of the first layer, H_C2Is the coercivity of the second layer
Power, M_S1Is the saturation magnetic moment of the first layer, M_S2Is the saturation magnetic moment of the second layer,
t₁Is the thickness of the first layer, t_TwoIs the thickness of the second layer, T_RIs room temperature, T_C1Is Curie of the first layer
Point, T_C1Is the Curie point of the second layer, which is the interface domain wall energy. [Action]   In the present invention, the laser beam is modulated in a pulse shape according to the information to be recorded.
. However, this itself has also been performed in conventional magneto-optical recording,
Beam intensity according to quantification information The means for modulating in a pulsed manner is a known means. For example, THE BELL SYSTEM TEC
HNICAL JOURNAL, Vol. 62 (1983), 1923-1936.   One of the characteristics of the present invention is that high and low levels of beam intensity are used.
You. That is, when the beam intensity is at a high level, the recording magnetic field (Hb) causes the recording auxiliary layer
The “A direction” magnetization is reversed in the “reverse A direction”, and the “reverse A direction”
The recording / reproducing layer has "reverse A direction" magnetization (or "A direction" magnetization)
Form bits. When the beam intensity is low, the “A direction”
Having a “A direction” magnetization (or “reverse A direction” magnetization)
To form   Given the required high and low levels, the modulation technique described in
Modulate beam intensity according to the invention with only partial modification of the stage This is easy for those skilled in the art.   In this specification,○○○ [or △] The expression is that when you first read XX outside of []
,below○○○ [or △In the case of], I will read XX outside of []
You. On the other hand, I did not read ○○○ first, but selected △ in [] and read it
Sometimes the following○○○ [or △], Do not read ○○○
Read △△△.   As is already known, when recording is not performed, for example, predetermined
Very low level laser beam to access recording location^*Light up
There is. Also, when the laser beam is also used for reproduction, a very low level^*
The laser beam may be turned on at the intensity. In the present invention, the laser
This very low level of beam intensity^*Sometimes. However, The very low level when forming the^*Higher than. So the example
For example, the output waveform of the laser beam in the present invention is as follows.   The modulation means used in the present invention is provided with high and low beam intensity levels.
If it can be obtained, it can be obtained by only partially modifying the conventional modulation means. Business
For such persons, such corrections are given high and low levels of beam intensity.
If Will be easy.   Further, the present invention provides a method for controlling the first layer having perpendicular magnetic anisotropy as a recording / reproducing layer.
Overwritable multilayer magneto-optical recording using a second layer having anisotropy as a recording auxiliary layer
Provide media.   The present invention is roughly classified into a first embodiment and a second embodiment. In any embodiment
Also, the recording medium has a multilayer structure, and this structure is divided as follows.   The first layer is a recording / reproducing layer having a high coercive force at room temperature and a low magnetization reversal temperature. 2nd layer
Is a recording auxiliary layer having a lower coercive force at room temperature and a higher magnetization reversal temperature than the first layer.
You. Each is composed of a perpendicular magnetization film. Note that both the first layer and the second layer are themselves multilayered.
It may be composed of a film. In some cases, a third layer exists between the first layer and the second layer.
May be present. Furthermore, there is no clear boundary between the first layer and the second layer.
The other may be changed to the other.   In the first embodiment, the coercive force of the recording / reproducing layer 1 is H_C1And that of the recording auxiliary layer 2 is H_C2
, The Curie point of the recording / reproducing layer 1 is set to T_C1, And that of the recording auxiliary layer 2_C2, Room temperature T_R,
The temperature of the recording medium when irradiating a low level laser beam is T_L, High level
T when the laser beam is irradiated_H, Recording / reproducing layer 1 is H_D1And the coupling magnetic field received by the recording auxiliary layer 2 is H_D2Then,
The recording medium satisfies the following equation 1 and satisfies the equations 2 to 5 at room temperature.
.The upper part is the case of the A (antiparallel) type medium described later, and the lower part is the case of the medium.
This is the case of a P (parallel) type medium described later. In addition, ferromagnetic material and magnetostatic
The combined medium belongs to the P type.   That is, the relationship between the coercive force and the temperature is represented by a graph as follows. Thin lines are recorded
Regeneration layer 1 The thick line indicates that of the recording auxiliary layer 2.  Therefore, when an initial auxiliary magnetic field (Hini.) Is applied to this recording medium at room temperature,
Then, only the magnetization of the recording auxiliary layer 2 is reversed without reversing the direction of the magnetization of the recording / reproducing layer 1.
You. Therefore, when an initial auxiliary magnetic field (Hini.) Is applied to the medium before recording, the recording auxiliary layer 2
of It can be magnetized. And Hini. Is zero Is kept as it is without re-inversion.   Only the recording auxiliary layer 2 by the initial auxiliary magnetic field (Hini.)The state is conceptually expressed as follows.   Here, the direction of magnetization in the recording / reproducing layer 1^*Is the information recorded so far.
Information. In the following description, since the direction is not related, it is indicated by X below. So
Then, the above table is represented as follows for the sake of simplicity.   Here, the medium temperature is set to T by irradiating a high-level laser beam._HRise to
Let Then T_HIs the Curie point T_C1Since the temperature is higher, the magnetization of the recording / reproducing layer 1 disappears.
Further T_HIs the Curie point T_C2Because it is near, the magnetization of the recording auxiliary layer 2 also disappears at all or almost disappears.
You. Here, the recording magnetic field (Hb) in the “A direction” or “reverse A direction” depending on the type of the medium
Is applied. The recording magnetic field (Hb) may be a floating magnetic field from the medium itself. Easy explanation
In this case, it is assumed that a recording magnetic field (Hb) in the “reverse A direction” is applied. The medium moves
Therefore, the irradiated part moves away from the laser beam immediately and is cooled by air.
Be rejected. When the temperature of the medium decreases in the presence of Hb, the magnetization of the recording auxiliary layer 2 becomes
In accordance with Hb, the magnetization is reversed to “reverse A direction” (state 2_H).  Then, the cooling is further advanced, and the medium temperature becomes T_C1If it goes down a little more, it will be recorded and played again
The magnetization of layer 1 appears You. In that case, magnetic coupling (in this specification, magnetic coupling means exchange coupling or
Or magnetostatic coupling), the direction of magnetization of the recording / reproducing layer 1 is
And the direction of magnetization of the recording auxiliary layer 2. That   The change in state due to this high-level laser beam is called a high-temperature cycle here.
I will do it.   Next, the medium temperature is set to T by irradiating a low-level laser beam._LTo rise. T_L
Is the Curie point T_C1Near or near, the magnetization of the recording / reproducing layer 1 is completely or almost lost.
But Curie point T_C2Since the temperature is lower, the magnetization of the recording auxiliary layer 2 does not disappear. Here, the recording magnetic field (Hb) is unnecessary, but Hb is turned on at a high speed (for a short time).
It cannot be turned off. Therefore, it is unavoidable that the temperature cycle
It has become.   But H_C2Is still large, the magnetization of the recording auxiliary layer 2 is
Will not turn. Since the medium is moving, the irradiated area is
Away from the air and cooled by air. As the cooling proceeds, the recording / reproducing layer 1
Magnetization appears. The direction of the appearing magnetization depends on the magnetization of the recording auxiliary layer 2 due to the magnetic coupling force.
Affected by the orientation. The magnetization does not change at room temperature.   The change in state due to this low-level laser beam is called a low-temperature cycle here.
I will do it.   As described above, no matter what the magnetization direction of the recording / reproducing layer 1 is,
And low temperature cycleBit is formed. In other words, the laser beam is turned to a high level (high temperature
Cycle) and low level (cold cycle)
Overwriting becomes possible.     For P-type media For A type media   The recording medium is generally in the form of a disk, and the medium is rotated during recording. That
Because it was recorded The portion (bit) is changed to Hini. As a result,
The magnetization of the auxiliary layer 2 is The influence of the magnetization of the recording auxiliary layer 2 does not affect the recording / reproducing layer 1, and therefore the recorded data is not recorded.
Information is retained.   If the recording / reproducing layer 1 is irradiated with linearly polarized light, the reflected light contains information.
Therefore, information is reproduced in the same manner as in a conventional magneto-optical recording medium.   The perpendicular magnetization film forming the recording / reproducing layer 1 and the recording auxiliary layer 2 has a compensation temperature.
Ferromagnetic material and ferrimagnetic material having Curie point without degree, and compensation temperature
Group consisting of amorphous or crystalline ferrimagnetic material having both the temperature and the Curie point
Selected from   The above is the description of the first embodiment bear using the Curie point. For it
The second embodiment is It utilizes the reduced Hc at a predetermined temperature higher than room temperature. 2nd fruit
The embodiment is the same as the T in the first embodiment._C1Recording / reproducing layer 1 is replaced with recording auxiliary layer 2
Temperature T at which magnetic coupling takes place_S1And use T_C2Instead of Hb
Reversing temperature T_S2Is used, the description is the same as in the first embodiment.   In the second embodiment, the coercive force of the recording / reproducing layer 1 is H_C1And that of the recording auxiliary layer 2 is H_C2
The temperature at which the recording / reproducing layer 1 is magnetically coupled to the recording auxiliary layer 2 is defined as T_S1And supplementary records
The temperature at which the magnetization of the auxiliary layer 2 is reversed by Hb is T_S2, Room temperature T_R, Low level laser beam
The temperature of the medium when irradiating the_LWhen irradiating a high level laser beam
T it_HAnd the coupling magnetic field received by the recording / reproducing layer 1 is H_D1The recording auxiliary layer 2 receives
The combined magnetic field is H_D2In this case, the recording medium satisfies the following expression 6, and at room temperature, the expressions 7 to 10
Is satisfied. This is the case of an A (antiparallel) type medium.
l) Type media.   In both the first and second embodiments, both the recording / reproducing layer 1 and the recording auxiliary layer 2 are made of a transition metal (
Selected from alloy compositions such as Fe, Co) -heavy rare earth metals (eg, Gd, Tb, Dy, etc.)
A recording medium that is an amorphous ferrimagnetic material is preferable.   Both the recording / reproducing layer 1 and the recording auxiliary layer 2 have a single transition metal.
A field selected from heavy rare earth metal alloy compositions In this case, the direction and magnitude of magnetization appearing outside each alloy are determined by the transition inside the alloy.
Spin direction and magnitude of metal atom (hereinafter abbreviated as TM) and heavy rare earth metal
It is determined by the relationship between the spin direction and magnitude of an atom (hereinafter abbreviated as RE). For example
TM And the spin of RE is expressed by the solid line vector ↑, and the magnetization direction of the entire alloy
And double sizeYou. However, among the alloys, TM spin and RE spin The alloy vector is zero (that is, the magnitude of the magnetization that appears to the outside is zero)
become. The alloy composition when this value reaches zero is the compensation composition
Called. Of other composition The alloy has a strength equal to the difference between the strengths of the two spins,
In the direction of the tor   The strength of each vector of TM spin and RE spin of a certain alloy composition is one of
When the alloy composition is large, the alloy composition becomes
For example, it is called RE rich.   For both the recording / reproducing layer 1 and the recording auxiliary layer 2, the TM-rich composition and the RE-rich
Composition. Therefore, the composition of the recording / reproducing layer 1 is written on the vertical axis coordinate.
When the composition of the recording auxiliary layer 2 is taken, the type of the medium of the present invention is divided into the following four quadrants.
Can be similar. The P type mentioned above belongs to the I and III quadrants.
Type A belongs to the quadrants II and IV.   On the other hand, looking at the change in coercive force with respect to temperature change, the Curie point (temperature at zero coercive force)
Before the temperature reaches 1), the coercive force once increases to infinity and then drops again
There is an alloy composition. The temperature corresponding to this infinity is called the compensation temperature (Tcomp.).
Devour. The compensation temperature is between room temperature and the Curie point for TM-rich alloy compositions.
Does not exist in between. Compensation temperatures below room temperature are meaningless in magneto-optical recording
Therefore, in this specification, the compensation temperature is the room temperature Let's say what exists between and the Curie point.   When classifying the presence or absence of the compensation temperature of the first layer and the second layer, the media are classified into four types.
being classified. The media in quadrant I includes all four types. Four types
Then, a "graph showing the relationship between coercive force and temperature" is written as follows. What
The thin line is that of the recording / reproducing layer 1 and the thick line is that of the recording auxiliary layer 2.Type 1 Type 2 Type 3 Type 4   Here, both the recording / reproducing layer 1 and the recording auxiliary layer 2 are RE-rich or TM-rich.
The recording medium is divided into the following 9 classes.
Classified as [Table 1] [Table 1 (continued)]   Here, class 1 recording media (P type, I quadrant, type 1) shown in Table 1
The principle of the method of the present invention will be described in detail by taking a specific medium No. 1 to which the present invention belongs as an example.
You.   This medium No. 1 has the following formula 11: Has the relationship This relationship is shown in the following graph. The thin line is the first
The graph of the layer is shown, and the thick line shows the graph of the second layer.   Room temperature T_R, The magnetization of the recording / reproducing layer 1 is changed to the initial auxiliary magnetic field Hini. Record supplement without reverse
The condition for inverting only the auxiliary layer 2 is represented by Expression 12. This medium No. 1 satisfies Expression 12.
Equation 12:   Where H_C1: Coercive force of recording / reproducing layer 1           H_C2: Coercive force of recording auxiliary layer 2           M_S1: 1 saturation magnetic moment           (saturation magnetization)           M_S2: Saturation magnetic moment of 2           t₁: 1 film thickness           t_Two: Film thickness of 2           σ_W： Interface domain wall energy           (interface wall energy)   At this time, Hini. Is represented by Expression 15. Hini. When there is no more
The magnetization of the recording auxiliary layer 2 is influenced by the magnetization of the recording / reproducing layer 1 due to the exchange coupling force. Receive. Nevertheless, the condition that the magnetization of the layer 2 is maintained without reversal is expressed by the following equations (13) to (14).
Is shown. This medium No. 1 satisfies Expressions 13 and 14.   The magnetization of the recording auxiliary layer 2 of the recording medium that satisfies the conditions of Expressions 12 to 14 at room temperature
Before the expression 15 The recording state remains (state 1). This state 1 is maintained until immediately before recording. Here, the recording magnetic field (Hb)
Applied.   Then, the medium temperature is set to T by irradiating a high-level laser beam._LAnd rise to
, T_LIs the Curie point T of the recording / reproducing layer 1_C1, So one magnetization disappears
(State 2_H). As irradiation continues, the temperature of the medium further increases. When the temperature of the medium is the recording auxiliary layer 2
T_comp.2When the temperature becomes slightly higher, the direction of each spin of RE and TM changes.
But the magnitude relationship is reversed   However, at this temperature H_C2Is still large, so that the magnetization of layer 2 is
It will not be turned over. The temperature further rises and T_H, The temperature of layer 2 is almost
Curie point T_C2And the magnetization of the layer 2 also disappears (state 4_H). This state 4_HThe temperature of the medium when it deviates from the spot area of the laser beam at
Begins to decline. The temperature of the medium is T_C2If it goes down a little more, layer 2 becomes magnetized Magnetization occurs (state 5_H). But the temperature is still T_C1Higher, layer 1 has magnetization
Does not appear.   Then, the temperature of the medium further decreases, and T_comp.2Below, RE and TM
Pin direction changes   This state 6_HThen the temperature of the medium is T_C1Higher, the magnetization of layer 1 still disappears.
Up to. Also, There is no inversion at ↑ Hb.   Then, the temperature further decreases and T_C1At a slightly lower level, magnetization appears in layer 1.
At that time, the exchange coupling force from the layer 2 shows the RE spins (↓) and the TM spins. Temperature is T_comp.1Because of this, TM spin is larger I do. This state is state 7_HIt is.  The medium temperature is in this state 7_HThe temperature further decreases from the temperature at the time of_comp.1Below
Then, the magnitude relationship between the RE spin and TM spin intensities of layer 1 is reversed. Yes (State 8_H).   Eventually, the temperature of the medium becomes state 8_HFrom room temperature to room temperature. Room
H at warm_C1Is sufficiently large that the magnetization of layer 1 is reversed by ΔHb. State 8_HIs held. In this way, the bit formation in the “reverse A direction”
Complete.   On the other hand, the medium temperature is reduced to T by irradiating a low-level laser beam._LTo rise. So
Then, T_LIs the Curie point T of the recording / reproducing layer 1_C1, The magnetization of layer 1
Disappears (state 2_L).  This state 2_LWhen the laser beam deviates from the spot area of the laser beam at
Begins to decline. Medium temperature T_C1If it goes down slightly, the recording auxiliary layer 2 It extends to each spin of the recording / reproducing layer 1. That is, R The magnetization appears to overcome the recording magnetic field ↑ Hb (state 3_L). The temperature in this state is T_c
omp.1Therefore, the TM spin is larger.   The medium temperature is further T_comp.1When cooled below, the RE spin of
And TM spin   This state 4_LCan be used even if the medium temperature drops to room temperature The formation is completed.   Next, it belongs to the class 2 recording media (P type, I quadrant, type 2) shown in Table 1.
The principle of the method of the present invention will be described in detail using a specific medium No. 2 as an example.
.   This medium No. 2 has the following formula 16: Has the relationship This relationship is shown in the following graph.  Room temperature T_R, The magnetization of the recording / reproducing layer 1 is changed to the initial auxiliary magnetic field Hini. Record supplement without reverse
Only magnetization of auxiliary layer 2 Equation 17 is a condition for reversing. This medium No. 2 satisfies Expression 17. Equation 17:   Where H_C1: Coercive force of recording / reproducing layer 1           H_C2: Coercive force of recording auxiliary layer 2           M_S1: 1 saturation magnetic moment           M_S2: Saturation magnetic moment of 2           t₁: 1 film thickness           t_Two: Film thickness of 2           σ_W： Interface domain wall energy   At this time, Hini. Is given by Expression 20. Hini. When there is no more
The magnetization of the recording auxiliary layer 2 is affected by the magnetization of the recording / reproducing layer 1 due to the exchange coupling force.
The conditions under which the magnetization of the layer 2 is maintained without being reversed again are expressed by Expressions 18 to 19.
This medium No. 2 satisfies Expressions 18 to 19.   The magnetization of the recording auxiliary layer 2 of the recording medium that satisfies the conditions of the expressions 17 to 19 at room temperature
Before the expression 20 The recording state remains (state 1). This state 1 is maintained until immediately before recording. Here, the recording magnetic field (Hb)
Applied.   Then, the medium temperature is set to T by irradiating a high-level laser beam._LAnd rise to
, T_LIs the Curie point T of the recording / reproducing layer 1_C1, So one magnetization disappears
(State 2_H). As irradiation continues, the temperature of the medium further increases. When the temperature of the medium is the recording auxiliary layer 2
T_comp.2When the temperature becomes slightly higher, the direction of each spin of RE and TM changes.
But the magnitude relationship is reversed   However, at this temperature H_C2Is still large, The magnetization of the layer 2 is not reversed by ↑ Hb. The temperature further rises and T_H
, The temperature of the medium, in particular, the layer 2 becomes almost the Curie point T_C2And the magnetization of layer 2 disappears
Yes (State 4_H). This state 4_HThe temperature of the medium when it deviates from the spot area of the laser beam at
Begins to decline. The temperature of the medium is T_C2If it goes down a little more, layer 2 becomes magnetized Magnetization occurs. But the temperature is still T_C1No magnetization appears in layer 1 because it is higher.
This state is state 5_HIt is.   Then, the temperature of the medium further decreases, and T_comp.2Less than At the bottom, the direction of each spin of RE and TM changes   This state 6_HThen the temperature of the medium is T_C1Higher, the magnetization of layer 1 still disappears.
Up to. In addition, H at that temperature_C2Is large, the magnetization of layer 2 is reversed by ΔHb
Never.   Then, the temperature further decreases and T_C1At a slightly lower level, magnetization appears in layer 1.
At that time, the exchange coupling force from the layer 2 shows the RE spins (↓) and the TM spins. State 7_HIt is.   Eventually, the temperature of the medium becomes state 7_HFrom room temperature to room temperature. Room
H at warm_C1Is sufficiently large that the magnetization of layer 1 is not reversed by ΔHb
, State 7_HIs held. Thus, the formation of the bit in the “reverse A direction” is completed.   On the other hand, the medium temperature is reduced to T by irradiating a low-level laser beam._LTo rise. So
Then, T_LIs the Curie point T of the recording / reproducing layer 1_C1, The magnetization of layer 1
Disappears (state 2_L).   This state 2_LLaser beam spot Outside of the media region, the media temperature begins to drop. Medium temperature T_C1A little less
And the recording auxiliary layer 2 It extends to each spin of the recording / reproducing layer 1. That is, R Magnetization appears (state 3_L).   This state 3_LDoes not change even when the medium temperature further decreases. As a result, the recording / reproducing layer
At 1, a bit in the “A direction” is formed.   Next, it belongs to the recording media of class 3 (P type, I quadrant, type 3) shown in Table 1.
The principle of the method of the present invention will be described in detail using a specific medium No. 3 as an example.
.   This medium No. 3 is represented by the following equation 21: Has the relationship This relationship is shown in the following graph.   Room temperature T_R, The magnetization of the recording / reproducing layer 1 is changed to the initial auxiliary magnetic field Hini. Record supplement without reverse
The condition for inverting only the auxiliary layer 2 is represented by Expression 22. This medium No. 3 satisfies Expression 22.
Equation 22:   Where H_C1: Coercive force of recording / reproducing layer 1           H_C2: Coercive force of recording auxiliary layer 2           M_S1: 1 saturation magnetic moment           M_S2: Saturation magnetic moment of 2           t₁: 1 film thickness           t_Two: Film thickness of 2           σ_W： Interface domain wall energy   At this time, Hini. Is represented by Expression 25. Hini. When there is no more
The magnetization of the recording auxiliary layer 2 is affected by the magnetization of the recording / reproducing layer 1 due to the exchange coupling force.
The conditions under which the magnetization of the layer 2 is maintained without being reversed again are shown by Expressions 23 and 24.
This medium Body No. 3 satisfies equations 23-24.   The magnetization of the recording auxiliary layer 2 of the recording medium that satisfies the conditions of Expressions 22 to 24 at room temperature
Before the expression 25The recording state remains (state 1). This state 1 is maintained until immediately before recording. Here, the recording magnetic field (Hb) is in the direction of ↓
Is applied to   Then, the medium temperature is set to T by irradiating a high-level laser beam._LAnd rise to
, T_LIs the Curie point T of the recording / reproducing layer 1_C1, So one magnetization disappears
(State 2_H). The irradiation of the beam continues, and the temperature of the medium becomes T_HThen T_HIs the T of the recording auxiliary layer 2.
_C1, The magnetization of the layer 2 also disappears (state 3_H).  This state 3_HWhen the laser beam deviates from the spot area of the laser beam at
Begins to decline. The temperature of the medium is T_C2If it goes down a little more, layer 2 becomes magnetized Magnetization occurs. But the temperature is still T_C1No magnetization appears in layer 1 because it is higher.
This state is state 4_HIt is.   Further, as the medium temperature decreases, T_C1At a slightly lower level, magnetization also appears in layer 1.
In this case, the magnetization of the layer 2 reaches the layer 1 by the exchange coupling force. As a result, RE work. In this case, the medium temperature is still T_comp.1As described above, the TM spin has a higher R
Bigger than E spin (State 5_H).  This state 5_HMedium temperature drops further from T_comp.1Below, the TM spin of layer 1 and RE (State 6_H).   Eventually, the temperature of the medium becomes state 6_HFrom room temperature to room temperature. Room
H at warm_C1Is sufficiently large, so that the magnetization of the layer 1 is stably maintained. Thus, "
Bit formation in the "inverse A direction" is completed.   On the other hand, the medium temperature is reduced to T by irradiating a low-level laser beam._LTo rise. So
Then, T_LIs the Curie point T of the recording / reproducing layer 1_C1, The magnetization of layer 1
Disappears. However, at this temperature,_C2Is large, the magnetization of layer 2 is ↓ It is not inverted by Hb (state 2_L).  This state 2_LWhen the laser beam deviates from the spot area of the laser beam at
Begins to decline. Medium temperature T_C1If it goes down slightly, the recording auxiliary layer 2 It extends to each spin of the recording / reproducing layer 1. That is, RE Appears. In this case, the temperature is T_comp.1Because of the above, the TM spin is larger
(State 3_L).   The medium temperature is further T_comp.1When cooled below, the RE spin of
And TM spin4_L).   This state 4_LCan be used even if the medium temperature drops to room temperature The formation is completed.   Next, it belongs to the recording medium of class 4 (P type, I quadrant, type 4) shown in Table 1.
The principle of the method of the present invention will be described in detail using a specific medium No. 4 as an example.
.   This medium No. 4 has the following equation 26: Has the relationship This relationship is shown in the following graph.  Room temperature T_R, The magnetization of the recording / reproducing layer 1 is changed to the initial auxiliary magnetic field Hini. Record supplement without reverse
The condition for inverting only the auxiliary layer 2 is represented by Expression 27. This medium No.4 is given by equation 27 To be satisfied. Equation 27:   Where H_C1: Coercive force of recording / reproducing layer 1           H_C2: Coercive force of recording auxiliary layer 2           M_S1: 1 saturation magnetic moment           M_S2: Saturation magnetic moment of 2           t₁: 1 film thickness           t_Two: Film thickness of 2           σ_W： Interface domain wall energy   At this time, Hini. Is represented by Expression 30. Hini. When there is no more
The magnetization of the recording auxiliary layer 2 is affected by the magnetization of the recording / reproducing layer 1 due to the exchange coupling force.
The conditions under which the magnetization of the layer 2 is maintained without being reversed again are shown by Expressions 28 to 29.
This medium No. 4 satisfies Expressions 28 to 29.   The magnetization of the recording auxiliary layer 2 of the recording medium that satisfies the conditions of Equations 27 to 29 at room temperature
Before the expression 30 The recording state remains (state 1). This state 1 is maintained until immediately before recording. Here, the recording magnetic field (Hb)
Applied.   And irradiate a high level laser beam Medium temperature T_LTo rise to T_LIs the Curie point T of the recording / reproducing layer 1_C1Almost
Therefore, the magnetization of 1 disappears (state 2_H).   Following the irradiation of the beam, the medium temperature further rises and T_H, The temperature T of the layer 2_HIs
Curie point T_C2, The magnetization of the layer 2 also disappears. This is state 3_HIn
You. This state 3_HThe temperature of the medium when it deviates from the spot area of the laser beam at
Begins to decline. The temperature of the medium is T_C2A little lower, the magnetization of layer 2 Magnetization appears. However, the temperature is T_C1taller than Therefore, no magnetization appears in the layer 1. This state is state 4_HIt is.  Then, the medium temperature further decreases, and T_C1If it goes down slightly, magnetization appears in layer 1.
You. At that time, the exchange coupling force from the layer 2 is between RE spins (↓), TM Is state 5_HIt is.   Then, the temperature of the medium will be 5_HFrom room temperature to room temperature. Room
H at warm_C1Is sufficiently large so that the magnetization of the layer 1 is stably maintained. Thus, "Reverse
Bit formation in the "A direction" is completed.   On the other hand, the medium temperature is reduced to T by irradiating a low-level laser beam._LTo rise. So
Then, T_LIs the Curie point T of the recording / reproducing layer 1_C1, The magnetization of layer 1
Disappears. In this state, H_C2Hama↓ Hb does not reverse. This state is state 2_LIt is.   This state 2_LWhen the laser beam deviates from the spot area of the laser beam at
Begins to decline. Medium temperature T_C1If it goes down slightly, the recording auxiliary layer 2 It extends to each spin of the recording / reproducing layer 1. That is, the exchange coupling force is between RE spins (↑).
, TM spins This state is state 3_LIt is.   This state 3_LCan be used even if the medium temperature drops to room temperature The formation is completed.   Next, the recording media of class 5 shown in Table 1 (A type, II quadrant, type 3)
The principle of the method of the present invention will be described in detail by taking the specific medium No. 5 to which the present invention belongs as an example.
You.   This medium No. 5 has the following formula 31: Has the relationship This leap engagement is shown in the following graph.   Room temperature T_R, The magnetization of the recording / reproducing layer 1 is changed to the initial auxiliary magnetic field Hini. Record supplement without reverse
The condition for inverting only the auxiliary layer 2 is represented by Expression 32. This medium No. 5 satisfies Expression 32.
Equation 32:   Where H_C1: Coercive force of recording / reproducing layer 1           H_C2: Coercive force of recording auxiliary layer 2           M_S1: 1 saturation magnetic moment           M_S2: Saturation magnetic moment of 2           t₁: 1 film thickness           t_Two: Film thickness of 2           σ_W： Interface domain wall energy   At this time, Hini. Is represented by Expression 35. Hini. When there is no more
The magnetization of the recording auxiliary layer 2 is affected by the magnetization of the recording / reproducing layer 1 due to the exchange coupling force.
The conditions under which the magnetization of the layer 2 is maintained without being reversed again are shown by Expressions 33 to 34.
This medium Body No. 5 satisfies equations 33-34.   At room temperature, the magnetization of the recording auxiliary layer 2 of the recording medium that satisfies the conditions of the equations (32) to (34) is
Before the expression 35 The recording state remains (state 1). This state 1 is maintained until immediately before recording. Here, the recording magnetic field (Hb) is in the direction of ↓
Is applied to   Then, the medium temperature is set to T by irradiating a high-level laser beam._LAnd rise to
, T_LIs the Curie point T of the recording / reproducing layer 1_C1, So one magnetization disappears
(State 2_H). The irradiation of the beam continues, and the temperature of the medium becomes T_HThen T_HIs T_C1Is approximately equal to
Therefore, the magnetization of the layer 2 also disappears (state 3_H).  This state 3_HWhen the laser beam deviates from the spot area of the laser beam at
Begins to decline. The temperature of the medium is T_C2A little lower, the magnetization of layer 2 Magnetization appears. However, the temperature is T_C1No magnetization appears in layer 1 because it is higher.
This state is state 4_HIt is.   Further, as the medium temperature decreases, T_C1At a slightly lower level, magnetization also appears in layer 1.
In this case, the magnetization of the layer 2 reaches the layer 1 by the exchange coupling force. As a result, RE work. In this case, the medium temperature is still T_comp.1As described above, the TM spin has a higher R
Bigger than E spin (State 5_H).  This state 5_HMedium temperature drops further from T_comp.1Below, the TM spin of layer 1 and RE (State 6_H).   Eventually, the temperature of the medium becomes state 6_HFrom room temperature to room temperature. Room
H at warm_C1Is sufficiently large so that the magnetization of the layer 1 is stably maintained. Thus, "A
The formation of the "direction" bit is completed.   On the other hand, the medium temperature is reduced to T by irradiating a low-level laser beam._LTo rise. So
Then, T_LIs the Curie point T of the recording / reproducing layer 1_C1, The magnetization of layer 1
Disappears. However, at this temperature,_C2Is large, the magnetization of layer 2 is
↓ Hb Is not inverted (state 2_L).   This state 2_LWhen the irradiation of the beam ends, the medium temperature starts to decrease. Medium temperature
Degree T_C1Less Influences each spin of the recording / reproducing layer 1 by the exchange coupling force. In other words, RE spin
(↓), TMs Manifest. In this case, the temperature is T_comp.1Because of the above, the TM spin is larger (state
State 3_L).   The medium temperature is further T_comp.1When cooled below, the RE spin of
And TM spin   This state 4_LCan be used even if the medium temperature drops to room temperature The formation is completed.   Next, it belongs to the recording medium of class 6 (A type, II quadrant, type 4) shown in Table 1.
The principle of the method of the present invention will be described in detail using a specific medium No. 6 as an example.
.   This medium No. 6 has the following formula 36: Has the relationship This relationship is shown in the following graph.  Room temperature T_R, The magnetization of the recording / reproducing layer 1 is changed to the initial auxiliary magnetic field Hini. Record supplement without reverse
Only auxiliary layer 2 is inverted The condition to be satisfied is Expression 37. This medium No. 6 satisfies Expression 37. Equation 37:   Where H_C1: Coercive force of recording / reproducing layer 1           H_C2: Coercive force of recording auxiliary layer 2           M_S1: 1 saturation magnetic moment           M_S2: Saturation magnetic moment of 2           t₁: 1 film thickness           t_Two: Film thickness of 2           σ_W： Interface domain wall energy   At this time, Hini. Is represented by Expression 40. Hini. When there is no more
The magnetization of the recording auxiliary layer 2 is affected by the magnetization of the recording / reproducing layer 1 due to the exchange coupling force.
The conditions under which the magnetization of the layer 2 is maintained without being reversed again are shown by Expressions 38 to 39.
This medium No. 6 satisfies Expressions 38 to 39.   The magnetization of the recording auxiliary layer 2 of the recording medium that satisfies the conditions of Expressions 37 to 39 at room temperature is
Before the expression 40 The recording state remains (state 1). This state 1 is held and maintained just before recording. Here, the recording magnetic field (Hb) is in the direction of ↓
Is applied to   Then, the medium temperature is set to T by irradiating a high-level laser beam._LAnd rise to
, T_LIs the Curie point T of the recording / reproducing layer 1_C1, So one magnetization disappears
(State 2_H).   Following the irradiation of the beam, the medium temperature further rises and T_H, The temperature T of the layer 2_HIs
T_C2, The magnetization of the layer 2 also disappears. This is state 3_HIt is. This state 3_HThe temperature of the medium when it deviates from the spot area of the laser beam at
Begins to decline. The temperature of the medium is T_C2A little lower, the magnetization of layer 2 Magnetization appears. However, the temperature is T_C1No magnetization appears in layer 1 because it is higher.
This state is state 4_HIt is.  Then, the medium temperature further decreases, and T_C1If it goes down slightly, magnetization appears in layer 1.
You. At that time, the exchange coupling force from the layer 2 is RE spins (同 士), TM Appear. This state is state 5_HIt is.   Then, the temperature of the medium eventually becomes state 5_HFrom room temperature to room temperature. Room
H at warm_C1Is enough Therefore, the magnetization of the layer 1 is stably maintained. This   On the other hand, the medium temperature is reduced to T by irradiating a low-level laser beam._LTo rise. So
Then, T_LIs the Curie point T of the recording / reproducing layer 1_C1, The magnetization of layer 1
Disappears. In this state, H_C2Hama ↓ Hb does not reverse. This state is state 2_LIt is.   This state 2_LWhen the laser beam deviates from the spot area of the laser beam at
Begins to decline. Medium temperature T_C1If it goes down slightly, the recording auxiliary layer 2 It extends to each spin of the recording / reproducing layer 1. Exchange coupling force You.   This state 3_LCan be used even if the medium temperature drops to room temperatureThe formation is completed. To be satisfied. Equation 42:   Where H_C1: Coercive force of recording / reproducing layer 1           H_C2: Coercive force of recording auxiliary layer 2           M_S1: 1 saturation magnetic moment           M_S2: Saturation magnetic moment of 2           t₁: 1 film thickness           t_Two: Film thickness of 2           σ_W： Interface domain wall energy   At this time, Hini. Is represented by Expression 45. Hini. When there is no more
The magnetization of the recording auxiliary layer 2 is affected by the magnetization of the recording / reproducing layer 1 due to the exchange coupling force.
The conditions under which the magnetization of the layer 2 is maintained without being reversed again are shown by equations 43 to 44.
This medium No. 7 satisfies Expressions 43 to 44.   Next, the recording media of class 7 shown in Table 1 (P type, III quadrant, type 4)
The principle of the method of the present invention will be described in detail by taking a specific medium No. 7 to which the present invention belongs as an example.
You.   This medium No. 7 has the following equation 41: Has the relationship This relationship is shown in the following graph.   Room temperature T_R, The magnetization of the recording / reproducing layer 1 is changed to the initial auxiliary magnetic field Hini. Record supplement without reverse
The condition for inverting only the auxiliary layer 2 is represented by Expression 42. This medium No. 7 is given by equation 42   The magnetization of the recording auxiliary layer 2 of the recording medium that satisfies the conditions of equations 42 to 44 at room temperature
Before the expression 45 The recording state remains (state 1). This state 1 is maintained until immediately before recording. Here, the recording magnetic field (Hb)
Applied.   And irradiate a high level laser beam Medium temperature T_LTo rise to T_LIs the Curie point T of the recording / reproducing layer 1_C1Almost
Therefore, the magnetization of 1 disappears (state 2_H).   Following the irradiation of the beam, the medium temperature further rises and T_H, The temperature T of the layer 2_HIs
Curie point T_C2, The magnetization of the layer 2 also disappears. This is state 3_HIn
You.This state 3_HThe temperature of the medium when it deviates from the spot area of the laser beam at
Begins to decline. The temperature of the medium is T_C2A little lower, the magnetization of layer 2 Magnetization appears. But the temperature is still T_C1Than Since it is high, no magnetization appears in layer 1. This state is state 4_HIt is.   Then, the medium temperature further decreases, and T_C1If it goes down slightly, magnetization appears in layer 1.
You. Then layer 2 State is state 5_HIt is.  Then, the temperature of the medium will be 5_HFrom room temperature to room temperature. Room
H at warm_C1Is sufficiently large so that the magnetization of the layer 1 is stably maintained. This   On the other hand, the medium temperature is reduced to T by irradiating a low-level laser beam._LTo rise. So
Then, T_LIs the Curie point T of the recording / reproducing layer 1_C1, The magnetization of layer 1
Disappears. In this state, H_C2Hama ↓ Hb does not reverse. This state is like bear 2_LIt is.   This state 2_LWhen the laser beam deviates from the spot area of the laser beam at
Begins to decline. Medium temperature T_C1If it goes down slightly, the recording auxiliary layer 2It extends to each spin of the recording / reproducing layer 1. Exchange coupling force State is state 3_LIt is.   This state 3_LCan be used even if the medium temperature drops to room temperature The formation is completed.   Next, it belongs to the class 8 recording media (A type, IV quadrant, type 2) shown in Table 1.
The principle of the method of the present invention will be described in detail by taking a specific medium No. 8 as an example.
.   This medium No. 8 has the following equation 46:Has the relationship This relationship is shown in the following graph.   Room temperature T_R, The magnetization of the recording / reproducing layer 1 is changed to the initial auxiliary magnetic field Hini. Record supplement without reverse
The condition for inverting only the auxiliary layer 2 is represented by Expression 47. This medium No.8 satisfies the formula 47 at room temperature
I do. Equation 47:   Where H_C1: Coercive force of recording / reproducing layer 1           H_C2: Coercive force of recording auxiliary layer 2           M_S1: 1 saturation magnetic moment           M_S2: Saturation magnetic moment of 2           t₁: 1 film thickness           t_Two: Film thickness of 2           σ_W： Interface domain wall energy   At this time, Hini. Is represented by Expression 50. Hini. When there is no more
The magnetization of the recording auxiliary layer 2 is affected by the magnetization of the recording / reproducing layer 1 due to the exchange coupling force.
The conditions under which the magnetization of the layer 2 is maintained without being reversed again are shown by Expressions 48 to 49.
This medium Body No. 8 satisfies equations 48-49.   The magnetization of the recording auxiliary layer 2 of the recording medium that satisfies the conditions of Equations 47 to 49 at room temperature is
Before the expression 50 The recording state remains (state 1).This state 1 is maintained until immediately before recording. Here, the recording magnetic field (Hb)
Applied.   Then, the medium temperature is set to T by irradiating a high-level laser beam._LAnd rise to
, T_LIs the Curie point T of the recording / reproducing layer 1_C1, So one magnetization disappears
(State 2_H). Further beam irradiation continues, and the medium temperature becomes T_comp.2When it gets a little harder, RE
Pin (↑) and T State is state 3_HIt is.  However, at this temperature H_C2Is still large, Further beam irradiation continues, so that the medium temperature further rises and T_HSay that
. Then T_HIs T_C2, The magnetization of the layer 2 also disappears (state 4_H).   This state 4_HWhen the laser beam deviates from the spot area of the laser beam at
Begins to decline. Medium temperature T_C2If it goes down a little more, the magnetization in layer 2 Appears. But the temperature is still T_C1Since it is higher, no magnetization appears in layer 1.
This state is state 5_HIt is.   Further, when the medium temperature is lowered, T_{comp, 2}Slightly below The orientation does not change, but the magnitude relationship is reversed It is not inverted by ↑ Hb. And the temperature is still T_C1Layer 1 because it is higher
Magnetization has not yet appeared. This bear is in state 6_HIt is.   Further, as the medium temperature decreases, T_C1At a slightly lower level, magnetization also appears in layer 1.
In this case, the layer 2 As a result, RE spins (↓), TM spins   Then, the temperature of the medium will eventually reach 7_HFrom room temperature to room temperature. Room
H at warm_C1Is sufficiently large so that the magnetization of the layer 1 is stably maintained. This   On the other hand, the medium temperature is reduced to T by irradiating a low-level laser beam._LTo rise. So
Then, T_LIs the Curie point T of the recording / reproducing layer 1_C1, The magnetization of layer 1
Disappears. However, at this temperature,_C2Is large, the magnetization of layer 2 is
It is not inverted by ↑ Hb (state 2_L).   This state 2_LWhen the laser beam deviates from the spot area of the laser beam at
Begins to decline. Medium temperature T_C1If it goes down slightly, the recording auxiliary layer 2It extends to each spin of the recording / reproducing layer 1. That is, RE Appears overcoming ΔHb. This state is state 3_LIt is.   This state 3_LCan be used even if the medium temperature drops to room temperature The formation is completed.   Next, it belongs to the recording medium of class 9 (A type, IV quadrant, type 4) shown in Table 1.
The principle of the method of the present invention will be described in detail by taking a specific medium No. 9 as an example.
.   This medium No. 9 has the following equation 51: Has the relationship This relationship is shown in the following graph.  Room temperature T_R, The magnetization of the recording / reproducing layer 1 is changed to the initial auxiliary magnetic field Hini. Record supplement without reverse
Only auxiliary layer 2 is inverted The condition to be satisfied is Expression 52. This medium No. 9 satisfies Expression 52. Equation 52:   Where H_C1: Coercive force of recording / reproducing layer 1           H_C2: Coercive force of recording auxiliary layer 2           M_S1: 1 saturation magnetic moment           M_S2: Saturation magnetic moment of 2           t₁: 1 film thickness           t_Two: Film thickness of 2           σ_W： Interface domain wall energy   At this time, Hini. Is represented by Expression 55. Hini. When there is no more
The magnetization of the recording auxiliary layer 2 is affected by the magnetization of the recording / reproducing layer 1 due to the exchange coupling force.
The conditions under which the magnetization of the layer 2 is maintained without being reversed again are shown by Expressions 53 to 54.
This medium No. 9 satisfies Expressions 53 to 54.   The magnetization of the recording auxiliary layer 2 of the recording medium that satisfies the conditions of Expressions 52 to 54 at room temperature
Before the expression 55 The recording state remains (state 1). The bear 1 is held until immediately before recording. Here, the recording magnetic field (Hb)
Applied.   Then, the medium temperature is set to T by irradiating a high-level laser beam._LAnd rise to
, T_LIs the Curie point T of the recording / reproducing layer 1_C1, The magnetization of layer 1 disappears
(State 2_H).   Following the irradiation of the beam, the medium temperature further rises and T_HBecomes the medium, especially layer 2
Temperature T_HIs T_C2, The magnetization of the layer 2 also disappears. This is state 3_HIs
. This state 3_HThe temperature of the medium when it deviates from the spot area of the laser beam at
Begins to decline. The temperature of the medium is T_C2A little lower, the magnetization of layer 2 Magnetization appears. However, this temperature is still T_C1The magnetization is higher in layer 1 because it is higher.
Not. This state is state 4_HIt is.  Then, the medium temperature further decreases, and T_C1If it goes down slightly, magnetization appears in layer 1.
You. Then layer 2 Appears. This state is state 5_HIt is.   Then, the temperature of the medium eventually becomes state 5_HFrom room temperature to room temperature. Room
H at warm_C1Is enough Therefore, the magnetization of the layer 1 is stably maintained. This   On the other hand, the medium temperature is reduced to T by irradiating a low-level laser beam._LTo rise. So
Then, T_LIs the Curie point T of the recording / reproducing layer 1_C1, The magnetization of layer 1
Disappears. In this state, H_C2Hama ↓ Hb does not reverse. This state is state 2_LIt is.   This state 2_LWhen the laser beam deviates from the spot area of the laser beam at
Begins to decline. Medium temperature T_C1If it goes down slightly, the recording auxiliary layer 2 It extends to each spin of the recording / reproducing layer 1. Exchange coupling force You.  This state 3_LCan be used even if the medium temperature drops to room temperature The formation is completed.   Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.
Not something. (Example 1) One of the media No. 1   Using a binary electron beam heating vacuum evaporation system, two evaporation sources shown in Table 2 below were used.
Put on.   A glass substrate with a thickness of 1.2 mm and a diameter of 200 mm is set in the chamber of the device
. Once inside the chamber of the device 1 × 10^-6Torr. Evacuate to the following degree of vacuum. afterwards
, Vacuum degree is 1-2 × 10^-6Torr. At a deposition rate of about 3 mm / sec.
Do. As a result, a 1000 mm thick Gd₁₄Dy₁₂Fe₇₄(Note: The subscript numbers are
Atomic%) of a first layer (recording / reproducing layer). Then, keep the vacuum
Replace the evaporation source. Then, vapor deposition is performed again, and a thickness of 2000 mm is formed on the first layer.
Gd_{twenty four}Tb_ThreeFe₇₃(A recording auxiliary layer) is formed. Both the first and second layers are perpendicular magnetization films.   Thus, double-layer magneto-optical recording belonging to class 1 (P type / I quadrant / type 1)
Medium No. 1 was produced.   The production conditions and characteristics of this medium are shown in Table 2 below. [Table 2]   This medium is T_L= 170 ° C, T_H= 230 ° C (see Example 13) Equation 11: And Equation 12: Are satisfied. Also, in equation 15,Therefore, the initial auxiliary magnetic field Hini. Is 600 Oe, Equation 15 is satisfied. To be so
Then, the magnetization of the recording / reproducing layer 1 becomes Hini. Recording inversion layer 2
Is reversed only.   Further, Equation 13: And Equation 14: Is satisfied, so Hini. Is removed, the magnetizations of layer 1 and layer 2 are respectively
Will be retained.   Therefore, Hini. = 600 Oe initial auxiliary magnetic field For example, a recording magnetic field of Hb = 600 Oe is applied in the "A direction".
This enables overwriting. Note that Hb and Hini. Size and orientation
In this case, use a recording device that combines one application means with another.
can do. (Example 2) One of the media No. 2   As in the case of the first embodiment, a 500-mm thick Tb₂₇Fe₇₃First layer (recording / reproducing layer) and
And 2000 Å thick Gd on it_{twenty four}Tb_ThreeFe₇₃(A recording auxiliary layer) is formed. this
Produces media No. 2 belonging to class 2 (P type, I quadrant, type 2)
Was done.   The production conditions and characteristics of this medium are shown in Table 3 below. [Table 3]   This medium is T_L= 150 ° C, T_H= 230 ° C (see Example 14) Equation 16: And equation 17:Are satisfied. Also, in equation 20, Therefore, the initial auxiliary magnetic field Hini. Is 600 Oe, Equation 20 is satisfied. To be so
Then, the magnetization of the recording / reproducing layer 1 becomes Hini. Recording inversion layer 2
Is reversed only.   Further, Equation 18: And Equation 19: Is satisfied, so Hini. Is removed, the magnetizations of layer 1 and layer 2 are respectively
Will be retained.   Therefore, Hini. = 600 Oe, for example, in the "A direction"
By applying a recording magnetic field of b = 600 Oe in the “A direction” ↑, overwriting is performed.
Will be possible. Note that Hb and Hini. In this case, the size and orientation of
It is possible to use a recording device in which each application unit is also used as one. (Embodiment 3) One of the media No. 3   As in the first embodiment, a 500-mm thick Gd_{twenty three}Tb_ThreeFe₇₄First layer (recording / reproducing layer)
And a 1000mm thick Tb on it₂₈Fe₆₅Co₇(A recording auxiliary layer) is formed. This
As a result, a medium No. 3 belonging to class 3 (P type, I quadrant, type 3) is manufactured.
Was built.   The production conditions and characteristics of this medium are shown in Table 4 below. [Table 4]   This medium is T_L= 170 ° C, T_H= 220 ° C (see Example 15), Equation 21:And Equation 22: Are satisfied. Also, in Equation 25, Therefore, the initial auxiliary magnetic field Hini. Is set to 4000 Oe, Equation 25 is satisfied. so
Then, the magnetization of the recording / reproducing layer 1 becomes Hini. Not inverted by the recording auxiliary layer
Only the magnetization of No. 2 is reversed.   Further, Equation 23: And Equation 24:Is satisfied, so Hini. Is removed, the magnetizations of layer 1 and layer 2 are respectively
Will be retained.   Therefore, Hini. = 4000 Oe, for example, in the "A direction"
Overwriting by applying a recording magnetic field of b = 300 Oe in the “reverse A direction” ↓
Becomes possible. (Embodiment 4) One of Medium No. 4   In the same manner as in the first embodiment, a Tb having a thickness of 1000₁₃Dy₁₃Fe₇₄Of the first layer (recording / reproducing layer
) And a 1000 Å thick Gd on it₁₄Dy₁₄Fe₇₂Forming a second layer (recording auxiliary layer)
I do. As a result, the media No. belonging to class 4 (P type, I quadrant, type 4)
.4 was produced.   The manufacturing conditions and characteristics of this medium are shown in Table 5 below. [Table 5]   This medium is T_L= 120 ° C, T_H= 160 ° C (see Example 16) Equation 26: And Equation 27: Are satisfied. Also, in Equation 30, Therefore, the initial auxiliary magnetic field Hini. Is set to 4000 Oe, Expression 30 is satisfied. so
Then, the magnetization of the recording / reproducing layer 1 becomes Hini. Not inverted by the recording auxiliary layer
Only the magnetization of No. 2 is reversed.   Further, Equation 28: And Equation 29:Is satisfied, so Hini. Is removed, the magnetizations of layer 1 and layer 2 are respectively
Will be retained.   Therefore, Hini. = 4000 Oe, an initial auxiliary magnetic field of, for example, "A direction"
By applying a recording magnetic field of Hb = 300 Oe in the “reverse A direction” ↓
Becomes possible. (Example 5: One of the media No. 5)   As in the first embodiment, a 500-mm thick Gd₁₃Dy₁₃Fe₇₄Of the first layer (recording / reproducing layer
) And 600mm thick Tb on it₁₈Fe₇₄Co₈(A recording auxiliary layer) is formed.
As a result, medium No. 5 belonging to class 5 (A type, second quadrant, type 3)
produced.   The production conditions and characteristics of this medium are shown in Table 6 below. [Table 6]   This medium is T_L= 165 ° C, T_H= 210 ° C (see Example 17) Equation 31: And Equation 32: Are satisfied. Also, in Equation 35, Therefore, the initial auxiliary magnetic field Hini. Is set to 4000 Oe, Expression 35 is satisfied. so
Then, the magnetization of the recording / reproducing layer 1 becomes Hini. Not inverted by the recording auxiliary layer
Only the magnetization of No. 2 is reversed.   Further, Equation 33: And Equation 34: Is satisfied, so Hini. Is removed, the magnetizations of layer 1 and layer 2 are respectively
Will be retained.   Therefore, Hini. = 4000 Oe, an initial auxiliary magnetic field of, for example, "A direction"
By applying a recording magnetic field of Hb = 300 Oe in the “reverse A direction” ↓
Becomes possible. (Embodiment 6: One of the media No. 6)   Using a ternary RF magnetron sputtering apparatus, the target shown in Table 7 below was used.
Get: Put three Tb, Fe, FeCo alloys. The target is first two Tb and Fe (binary
) And then two (binary) Tb and FeCo alloys. 1.2mm thick, straight
A glass substrate having a diameter of 200 mm is set in a chamber of the apparatus.   Once inside the chamber of the device,^-7Torr. After evacuating to the following vacuum,
5 × 10^-3Torr. Introduce. Then, at a deposition rate of about 2 mm / sec,
Perform puttering. As a result, a 500 mm thick Tb₂₇Fe₇₃The first layer (
Recording / reproducing layer). Next, change the target while maintaining the vacuum state.
You. Then, another sputtering is performed, and a Tb having a thickness of 1000 に is formed on the first layer.₁₈Fe₇₄
Co₈(A recording auxiliary layer) is formed. Both the first and second layers are perpendicular magnetization films.
You.   Thus, the dual-layer magneto-optical recording belonging to class 6 (A type, second quadrant, type 4)
Recording medium No. 6 was manufactured.   The production conditions and characteristics of this medium are shown in Table 7 below. [Table 7]  This medium is T_L= 155 ° C, T_H= 220 ° C (see Example 18), Equation 36: And Equation 37: Are satisfied. Also, in Equation 40,Therefore, the initial auxiliary magnetic field Hini. Is 4000 Oe, Equation 40 is satisfied. so
Then, the magnetization of the recording / reproducing layer 1 becomes Hini. Not inverted by the recording auxiliary layer
Only the magnetization of No. 2 is reversed.   Further, Equation 38: And Equation 39: Is satisfied, so Hini. Is removed, the magnetizations of layer 1 and layer 2 are respectively
Will be retained.   Therefore, Hini. = 4000 Oe, an initial auxiliary magnetic field of, for example, "A direction"
By applying a recording magnetic field of Hb = 300 Oe in the “reverse A direction” ↓
Becomes possible. (Embodiment 7: One of the media No. 7)   In the same manner as in the sixth embodiment, a 1000-mm-thick Tb_{twenty one}Fe₇₉First layer (recording / reproducing layer) and
And a 1000mm thick Tb on it₁₈Fe₇₄Co₈(A recording auxiliary layer) is formed. this
Produces media No. 7 belonging to class 7 (P type, third quadrant, type 4)
Was done.   The production conditions and characteristics of this medium are shown in Table 8 below. [Table 8]   This medium is T_L= 155 ° C, T_H= 220 ° C (see Example 19) Equation 41: And Equation 42: Are satisfied. Also, in Equation 45,Therefore, the initial auxiliary magnetic field Hini. Is set to 4000 Oe, Expression 45 is satisfied. so
Then, the magnetization of the recording / reproducing layer 1 becomes Hini. Not inverted by the recording auxiliary layer
Only the magnetization of No. 2 is reversed.   Further, Equation 43: And Equation 44: Is satisfied, so Hini. Is removed, the magnetizations of layer 1 and layer 2 are respectively
Will be retained.   Therefore, Hini. = 4000 Oe, an initial auxiliary magnetic field of, for example, "A direction"
By applying a recording magnetic field of Hb = 300 Oe in the “reverse A direction” ↓
Becomes possible. (Embodiment 8: One of the media No. 8)   As in the case of the sixth embodiment, a 500 mm thick Tb_{twenty one}Fe₇₉First layer (recording / reproducing layer) and
And 2000 Å thick Gd on it_{twenty four}Tb_ThreeFe₇₃(A recording auxiliary layer) is formed. this
Produces media No. 8 belonging to class 8 (A type, IV quadrant, type 2)
Was done.   The production conditions and characteristics of this medium are shown in Table 9 below. [Table 9]   This medium is T_L= 155 ° C, T_H= 230 ° C (see Example 20), Equation 46: And Equation 47: Are satisfied. Also, in Equation 50,Therefore, the initial auxiliary magnetic field Hini. Is set to 800 Oe, Expression 50 is satisfied. so
Then, the magnetization of the recording / reproducing layer 1 becomes Hini. Not inverted by the recording auxiliary layer
Only the magnetization of No. 2 is reversed.   Further, Equation 48: And Equation 49: Is satisfied, so Hini. Is removed, the magnetizations of layer 1 and layer 2 are respectively
Will be retained.   Therefore, Hini. = 800 Oe, for example, in the “A direction” ↑,
Overwriting by applying a recording magnetic field of Hb = 800 Oe in “A direction” ↑
Becomes possible. Note that Hb and Hini. In this case, the size and orientation of
It is possible to use a recording device in which each of the application means is shared. (Embodiment 9) One of the media No. 9   In the same manner as in the first embodiment, a 1000 mm thick Gd_FourTb₁₉Fe₇₇Of the first layer (recording / reproducing layer
) And 500mm thick Tb on it₂₉Fe₆₁Co_Ten(A recording auxiliary layer) is formed.
Thus, medium No. 9 belonging to class 9 (A type, IV quadrant, type 4)
produced.   The production conditions and characteristics of this medium are shown in Table 10 below. [Table 10]   This medium is T_L= 170 ° C, T_H= 220 ° C (see Example 21) Equation 51: And equation 52: Are satisfied. Also, in Equation 55, Therefore, the initial auxiliary magnetic field Hini. Is set to 4000 Oe, Expression 55 is satisfied. so
Then, the magnetization of the recording / reproducing layer 1 becomes Hini. Not inverted by the recording auxiliary layer
Only the magnetization of No. 2 is reversed.   Further, Equation 53: And Equation 54: Is satisfied, so Hini. Is removed, the magnetizations of layer 1 and layer 2 are respectively
Will be retained.   Therefore, Hini. = 4000 Oe, an initial auxiliary magnetic field of, for example, "A direction"
By applying a recording magnetic field of Hb = 300 Oe in the “reverse A direction” ↓
Becomes possible. (Example 10: magneto-optical recording apparatus)   This apparatus is exclusively for recording, and its overall configuration is shown in FIG. 3 (conceptual diagram).   This device is basically   (A) rotating means 21 as an example of means for moving recording medium 20;   (B) Initial auxiliary magnetic field Hini. Application means 22;   (C) laser beam light source 23;   (D) In accordance with the binarized information to be recorded, the beam intensity is set to (1) the magnetization is upward.
Suitable for forming either a bit or a bit with downward magnetization
Medium temperature T_HAnd (2) a medium suitable for forming the other bit.
Body temperature T_LMeans 24 for pulsating modulation to a low level to provide   (E) recording magnetic field Hb applying means 25; Consists of   The recording magnetic field Hb applying means 25 is generally an electromagnet or preferably a permanent magnet.
. In some cases, the recording magnetic field Hb rises from a portion other than the recording track of the recording medium.
A free magnetic field may be used. In this case, the applying means 25
It refers to a region of the magnetized film (first and second layers) where a stray magnetic field is generated.   Here, as the application means 25, Hb = 300 Oe and the direction of the magnetic field is “inverse A direction”.
Use the permanent magnet ↓. This permanent magnet 25 is located in the radial direction of the disk-shaped medium 20.
Is fixedly installed. The permanent magnet 25
Should not be moved together with the recording head (pickup) including the light source 23.
And That makes the pickup lighter and enables high-speed access.   The initial auxiliary magnetic field Hini. As the application means 22, an electromagnet or preferably permanent
Magnets are used. Here, Hini. = 4000 Oe, use a permanent magnet whose magnetic field direction is “A direction” 向 き
. The permanent magnet 22 has a length corresponding to the radial length of the disk-shaped medium.
Fix and install a rod-shaped object.   It should be noted that the present recording apparatus may be modified to a recording / reproducing apparatus by adding a reproducing system apparatus.
Good. (Example 11: magneto-optical recording apparatus)   This device is exclusively for recording, and its overall configuration is shown in FIG. 4 (conceptual diagram).   This device is basically   (A) rotating means 21 as an example of means for moving recording medium 20;   (C) laser beam light source 23;   (D) In accordance with the binarized information to be recorded, the beam intensity is set to (1) the magnetization is upward.
Suitable for forming either a bit or a bit with downward magnetization
Medium temperature T_HAnd (2) a medium suitable for forming the other bit.
Body temperature T_LMeans 24 for pulsating modulation to a low level to provide   (B, e) Initial auxiliary magnetic field Hini. A recording magnetic field Hb applying hand also serving as the applying means 22
Step 25; Consists of   The direction of the recording magnetic field Hb and the initial auxiliary magnetic field Hini. When the orientation matches,
The magnetic field Hb applying means 25 and the initial auxiliary magnetic field Hini. It can be used also as the application means 22.
May be possible. This is the case as follows. Recording pieces to temporarily concentrate the magnetic field
The recording magnetic field Hb applying means 25 is installed at a place (a spot area where the beam is hit).
However, it is impossible to concentrate the magnetic field at one point. In other words, around the recording location
The leakage magnetic field is always applied. Therefore, if this leakage magnetic field is used, the recording
Before the initial auxiliary magnetic field Hini. It is possible to apply a magnetic field. Therefore, in this embodiment,
In the apparatus, the means 22 and 25 are also used.   The combined means 22 & 25 are generally electromagnets or preferably permanent magnets.
Here, Hb = Hini. = 600 Oe and the direction of the magnetic field is "A direction".
use. The permanent magnets 22 & 25 have a length in the radial direction of the disk-shaped recording medium 20.
Sani It is a rod having a corresponding length. These magnets 22 & 25 are
It must be fixed and not moved with the pickup including the light source 23.
And That makes the pickup lighter and enables high-speed access. (Example 12: magneto-optical recording apparatus)   This device is exclusively for recording, and its overall configuration is shown in FIG. 4 (conceptual diagram).   This device is basically   (A) rotating means 21 as an example of means for moving recording medium 20;   (C) laser beam light source 23;   (D) In accordance with the binarized information to be recorded, the beam intensity is set to (1) the magnetization is upward.
Suitable for forming either a bit or a bit with downward magnetization
Medium temperature T_HAnd (2) a medium suitable for forming the other bit.
Body temperature T_LMeans 24 for pulsating modulation to a low level to provide   (B, e) Initial auxiliary magnetic field Hini. A recording magnetic field Hb applying hand also serving as the applying means 22
Step 25; Consists of   As the combined means 22 & 25, here, Hb = Hini. = 800 Oe for magnetic
Use a permanent magnet whose field direction is "A direction". These permanent magnets 22 & 25
A disk-shaped recording medium having a length corresponding to the radial length of the disk-shaped recording medium 20;
You. The magnets 22 and 25 are fixedly installed on the recording apparatus,
We will not move them with the make-up. (Example 13: magneto-optical recording apparatus)   Magneto-optical recording is performed using the recording apparatus of the eleventh embodiment (see FIG. 4). First,
The recording medium 20 of the first embodiment is moved at a constant linear velocity of 8.5 m / sec by the rotating means 21.
. The medium 20 is irradiated with a laser beam. This beam is applied to means 24
Higher level: 9.3 mW (on disk), Low level: 6.6 mW (on disk)
Has been adjusted as follows. The beam is then pulsed according to the information by means 24.
Modulated. Here, the information to be recorded is a signal having a frequency of 1 MHz. Therefore,
The medium 20 was irradiated while modulating the beam at a frequency of 1 MHz. Thereby, 1MH
The signal at z should have been recorded. When reproduced by another magneto-optical reproducing device, the C / N ratio becomes
It was 51 dB and it was confirmed that it was recorded.   Next, a signal having a frequency of 5 MHz is added to the already recorded area of the medium 20 with new information.
As recorded. When this information was reproduced in the same manner, new information was reproduced at a C / N ratio of 48 dB. error
The incidence is 10^-Five~Ten^-6Met. At this time, the 1MHz signal (previous information) is completely
Was not.   As a result, it was found that overwriting was possible.   Under this condition, the temperature of the medium is at a high level: T_H= 230 ° C, low level
: T_L= 170 ° C. (Example 14: magneto-optical recording)   Magneto-optical recording is performed using the recording apparatus of the eleventh embodiment (see FIG. 4). First,
The recording medium 20 of the second embodiment is moved at a constant linear velocity of 8.5 m / sec by the rotating means 21.
. The medium 20 is irradiated with a laser beam. This beam is applied to means 24
Higher level: 9.3 mW (on disk), Low level: 5.7 mW (on disk)
Adjusted as I have. The beam is then pulsed by means 24 according to the information. here
Here, the information to be recorded is a signal having a frequency of 1 MHz. Therefore, the beam is set to frequency 1
The medium 20 was irradiated while being modulated at MHz. This records a 1MHz signal.
Must have been. When reproduced by another magneto-optical device, the C / N ratio is 52 dB,
It was confirmed that it was done.   Next, a signal having a frequency of 5 MHz is added to the already recorded area of the medium 20 with new information.
As recorded. When this information is reproduced in the same way, new information is reproduced at a C / N ratio of 49 dB.
Was born. Error rate is 10^-Five~Ten^-6Met. At this time, the 1MHz signal (before
Information) did not appear at all.   As a result, it was found that overwriting was possible.   Under this condition, the temperature of the medium is at a high level: T_H= 230 ° C, low level
: T_L= 150 ° C Reach. (Example 15: magneto-optical recording)   Magneto-optical recording is performed using the recording apparatus of the tenth embodiment (see FIG. 3). First,
The recording medium 20 of the third embodiment is moved at a constant linear velocity of 8.5 m / sec by the rotating means 21.
. The medium 20 is irradiated with a laser beam. This beam is applied to means 24
Higher level: 8.9 mW (on disk), lower level: 6.6 mW (on disk)
Has been adjusted as follows. The beam is then pulsed according to the information by means 24.
Modulated. Here, the information to be recorded is a signal having a frequency of 5 MHz. Therefore,
The medium 20 was irradiated while the beam was modulated at a frequency of 5 MHz. With this, 5MH
The signal at z should have been recorded. When reproduced by another magneto-optical reproducing device, the C / N ratio becomes
It was 51 dB and it was confirmed that it was recorded.   Next, a signal having a frequency of 2 MHz is newly added to the already recorded area of the medium 20.
As recorded. When this information is reproduced in the same way, new information is reproduced at a C / N ratio of 54 dB.
Was born. Error rate is 10^-Five~Ten^-6Met. At this time, the 5MHz signal (before
Information) did not appear at all.   As a result, it was found that overwriting was possible.   Under this condition, the temperature of the medium is at a high level: T_H= 220 ° C, low level
: T_L= 170 ° C. (Example 16: magneto-optical recording)   Magneto-optical recording is performed using the recording apparatus of the tenth embodiment (see FIG. 3). First,
The recording medium 20 of the fourth embodiment is moved at a constant linear velocity of 8.5 m / sec by the rotating means 21.
. The medium 20 is irradiated with a laser beam. This beam is applied to means 24
Than High level: 6.1 mW (on disk), Low level: 4.3 mW (on disk)
Has been adjusted. The beam is modulated in a pulse form according to the information by means 24
Is done. Here, the information to be recorded is a signal having a frequency of 5 MHz. Therefore, bee
The medium 20 was irradiated while the medium was modulated at a frequency of 5 MHz. This allows the 5MHz
The signal should have been recorded. When reproduced by another magneto-optical reproducing device, the C / N ratio is 47 dB.
It was confirmed that it was recorded.   Next, a signal having a frequency of 2 MHz is newly added to the already recorded area of the medium 20.
As recorded. When this information is reproduced in the same way, new information is reproduced at a C / N ratio of 50 dB.
Was born. Error rate is 10^-Five~Ten^-6Met. At this time, the 5MHz signal (before
Information) did not appear at all.   As a result, it was found that overwriting was possible.   Under this condition, the temperature of the medium is at a high level: T_H= 160 ° C, low level
: T_L= 120 ° C. (Example 17: magneto-optical recording)   Magneto-optical recording is performed using the recording apparatus of the tenth embodiment (see FIG. 3). First,
The recording medium 20 of the fifth embodiment is moved at a constant linear velocity of 8.5 m / sec by the rotating means 21.
. The medium 20 is irradiated with a laser beam. This beam is applied to means 24
Higher level: 8.4 mW (on disk), lower level: 6.4 mW (on disk)
Has been adjusted as follows. The beam is then pulsed according to the information by means 24.
Modulated. Here, the information to be recorded is a signal having a frequency of 5 MHz. Therefore,
The medium 20 was irradiated while the beam was modulated at a frequency of 5 MHz. With this, 5MH
The signal at z should have been recorded. When played back by another magneto-optical playback device, The C / N ratio was 48 dB, confirming that it was recorded.   Next, a signal having a frequency of 4 MHz is newly added to the already recorded area of the medium 20.
As recorded. When this information is reproduced in the same way, new information is reproduced at a C / N ratio of 49 dB.
Was born. Error rate is 10^-Five~Ten^-6Met. At this time, the 5MHz signal (before
Information) did not appear at all.   As a result, it was found that overwriting was possible.   Under this condition, the temperature of the medium is at a high level: T_H= 210 ° C, low level
: T_L= 165 ° C. (Example 18: magneto-optical recording)   Magneto-optical recording is performed using the recording apparatus of the tenth embodiment (see FIG. 3). First,
The recording medium 20 of the sixth embodiment is rotated at a constant linear velocity of 8.5 m / sec by the rotating means 21. To move. The medium 20 is irradiated with a laser beam. This beam
By means 24, at high level: 8.1 mW (on disk), at low level: 5.9 mW (on disk)
Has been adjusted so that the output of. The beam is then subject to the information by means 24.
It is modulated in a pulse shape. Here, the information to be recorded is a signal with a frequency of 5 MHz.
Was. Therefore, the medium 20 was irradiated while modulating the beam at a frequency of 5 MHz. this
As a result, a signal of 5 MHz should have been recorded. Reproducing with another magneto-optical reproducing device
It was confirmed that the C / N ratio was 49 dB, which was recorded.   Next, a signal having a frequency of 3 MHz is newly added to the already recorded area of the medium 20.
As recorded. When this information is reproduced in the same way, new information is reproduced at a C / N ratio of 51 dB.
Was born. Error rate is 10^-Five~Ten^-6Met. At this time, the 5MHz signal (before
Information) did not appear at all.   As a result, it was found that overwriting was possible.   Under this condition, the temperature of the medium is at a high level: T_H= 220 ° C, low level
: T_L= 155 ° C. (Example 19: magneto-optical recording)   Magneto-optical recording is performed using the recording apparatus of the tenth embodiment (see FIG. 3). First,
The recording medium 20 of the seventh embodiment is moved at a constant linear velocity of 8.5 m / sec by the rotating means 21.
. The medium 20 is irradiated with a laser beam. This beam is applied to means 24
Higher level: 8.9 mW (on disk), lower level: 5.9 mW (on disk)
Has been adjusted as follows. The beam is then pulsed according to the information by means 24.
Modulated. Here, the information to be recorded is a signal having a frequency of 5 MHz. Therefore,
The beam is irradiated on the medium 20 while being modulated at a frequency of 5 MHz. Fired. This should have recorded a 5 MHz signal. Another magneto-optical reproducing device
When it was played back on the device, the C / N ratio was 49 dB, confirming that it was recorded.   Next, a signal having a frequency of 2 MHz is newly added to the already recorded area of the medium 20.
As recorded. When this information is reproduced in the same manner, new information is reproduced at a C / N ratio of 52 dB.
Was born. Error rate is 10^-Five~Ten^-6Met. At this time, the 5MHz signal (before
Information) did not appear at all.   As a result, it was found that overwriting was possible.   Under this condition, the temperature of the medium is at a high level: T_H= 220 ° C, low level
: T_L= 155 ° C. (Example 20: magneto-optical recording)   Using the recording device of Example 12 (see FIG. 4) Perform magneto-optical recording. First, the recording medium 20 of the eighth embodiment is rotated 8.5 m by the rotating means 21.
Move at a constant linear velocity of / sec. The medium 20 is irradiated with a laser beam.
You. This beam is emitted by means 24 at high level: 9.3 mW (on disk), at low level
: Adjusted to output 5.9 mW (on disk). And the beam means
The signal is modulated into a pulse shape according to the information by 24. Here, the information to be recorded is
A signal of several 1 MHz was used. Therefore, the medium 2 is modulated while modulating the beam at a frequency of 1 MHz.
0 was irradiated. As a result, a signal of 1 MHz should have been recorded. Another magneto-optical
When played back on a playback device, the C / N ratio was 52 dB, confirming that the data was recorded.
Was.   Next, a signal having a frequency of 2 MHz is newly added to the already recorded area of the medium 20.
As recorded. When this information is reproduced in the same way, new information is reproduced at a C / N ratio of 51 dB.
Was born. Error rate is 10^-Five~ Ten^-6Met. At this time, no 1 MHz signal (previous information) appeared.   As a result, it was found that overwriting was possible.   Under this condition, the temperature of the medium is at a high level: T_H= 230 ° C, low level
: T_L= 155 ° C. (Example 21: magneto-optical recording)   Magneto-optical recording is performed using the recording apparatus of the tenth embodiment (see FIG. 3). First,
The recording medium 20 of the ninth embodiment is moved at a constant linear velocity of 8.5 m / sec by the rotating means 21.
. The medium 20 is irradiated with a laser beam. This beam is applied to means 24
Higher level: 8.9 mW (on disk), lower level: 6.6 mW (on disk)
Has been adjusted as follows. The beam is then pulsed according to the information by means 24.
Modulated. Here should be recorded The information was a signal with a frequency of 5 MHz. Therefore, do not modulate the beam at a frequency of 5 MHz.
The medium 20 was irradiated. This should have recorded a 5 MHz signal.
When reproduced by another magneto-optical reproducing device, the C / N ratio is 51 dB,
I was assured.   Next, a signal having a frequency of 6 MHz is newly added to the already recorded area of the medium 20.
As recorded. When this information is reproduced in the same way, new information is reproduced at a C / N ratio of 49db.
Was born. Error rate is 10^-Five~Ten^-6Met. At this time, the 5MHz signal (before
Information) did not appear at all.   As a result, it was found that overwriting was possible.   Under this condition, the temperature of the medium is at a high level: T_H= 220 ° C, low level
: T_L= 170 ° C. 〔The invention's effect〕   As described above, according to the present invention, in magneto-optical recording, the recording magnetic field Hb is turned on,
Overwriting starts without turning off or changing the direction of Hb.
It became possible.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conceptual diagram illustrating a recording principle of a magneto-optical recording method. FIG. 2 is a conceptual diagram illustrating the reproducing principle of the magneto-optical recording method. FIG. 3 is a conceptual diagram showing an overall configuration of a magneto-optical recording device according to Example 10 of the present invention. FIG. 4 is a conceptual diagram showing the entire configuration of a magneto-optical recording device according to Examples 11 and 12 of the present invention. Description of main parts of the code] L ......... laser beam L _P ...... linearly polarized light B ₁ ...... "A direction" bits B ₀ ...... "non-A direction" having a magnetization bit 1 ......... recorded with magnetization Reproducing layer 20... Magneto-optical recording medium 20 a. Substrate 21... Means for moving the recording medium or rotating means 22 as an example thereof... Initial auxiliary magnetic field Hini, applying means 23... Laser beam light source 24. According to the binarized information, the beam intensity is increased to a high level that gives the medium an appropriate temperature to form either a bit with "A" magnetization or a bit with "reverse A" magnetization. (2) means for pulse-modulating the medium to a low level which gives an appropriate temperature to the medium for forming the other bit 25 means for applying the recording magnetic field Hb

Claims (1)

[Claims] 1. In a magneto-optical recording method for recording information on a recording / reproducing layer of a magneto-optical recording medium with bits having upward magnetization and bits having downward magnetization, the method comprises the steps of: It comprises at least two layers of a first layer having anisotropy and a second layer having perpendicular magnetic anisotropy as a recording auxiliary layer, both layers are magnetically coupled, and the magnetization of the first layer is An overwritable multilayer magneto-optical recording medium in which the magnetization of the second layer can be aligned either upward or downward without changing the orientation, and the magnetization of the second layer is changed at least in a region to be recorded. Preparing a medium aligned either upward or downward; (b) moving the medium; (c) irradiating the medium with a laser beam; (d) recording the beam intensity 2 According to the value information (E) applying a recording magnetic field to the medium portion irradiated with the beam; (f) when the intensity of the beam is at a high level, a bit having an upward magnetization and a bit having a downward magnetization Forming one of the bits and forming the other bit when the intensity of the beam is at a low level. 2. When the magnetization of the recording auxiliary layer is aligned in the “A direction”, which is either upward or downward, when the beam intensity is at a high level, the “A direction” magnetization of the recording auxiliary layer is caused by the recording magnetic field. Is inverted to the “reverse A direction”, and a bit having “reverse A direction” magnetization (or “A direction” magnetization) is formed in the recording / reproducing layer by the “reverse A direction” magnetization of the recording auxiliary layer, and the beam intensity is reduced. A bit having "A direction" magnetization (or "reverse A direction" magnetization) is formed in the recording / reproducing layer by the "A direction" magnetization of the recording auxiliary layer when the level is low. 2. The magneto-optical recording method according to claim 1. 3. In a magneto-optical recording device, the device comprises: (a) at least a first layer having perpendicular magnetic anisotropy as a recording / reproducing layer and a second layer having perpendicular magnetic anisotropy as a recording auxiliary layer; It is composed of two layers, both layers are magnetically coupled, and the overwritable multilayer light capable of aligning the magnetization of the second layer either upward or downward without changing the direction of the magnetization of the first layer. Means for moving the magnetic recording medium; (b) before irradiating the medium with the laser beam, application of an initial auxiliary magnetic field for aligning the magnetization direction of at least the second layer of the area to be recorded to one of the upward and downward directions Means; (c) a laser beam light source; (d) a beam intensity according to the binary information to be recorded; (1) necessary to form one of a bit having an upward magnetization and a bit having a downward magnetization. Medium temperature Means for pulse-modulating between a high level to be applied and (2) a low level to apply the temperature necessary for forming the other bit to the medium; (e) near the beam irradiation position, A recording magnetic field applying means which does not modulate a magnetic field which may also be used as a magnetic field applying means. 4. In a magneto-optical recording device, the device comprises: (a) at least a first layer having perpendicular magnetic anisotropy as a recording / reproducing layer and a second layer having perpendicular magnetic anisotropy as a recording auxiliary layer; It is composed of two layers, both layers are magnetically coupled, and the overwritable multilayer light capable of aligning the magnetization of the second layer either upward or downward without changing the direction of the magnetization of the first layer. Means for moving a medium in which the magnetization of the second layer is aligned either upward or downward in at least a region to be recorded; (b) a laser beam light source; (c) recording (1) a high level that gives the medium the temperature necessary to form either a bit having an upward magnetization or a bit having a downward magnetization; (2) Form the other bit (D) a recording magnetic field applying means which is near the beam irradiation position and does not modulate the magnetic field; and (d) means for applying a recording magnetic field which does not modulate the magnetic field. Overwritable magneto-optical recording device. 5. It comprises at least two layers, a first layer having perpendicular magnetic anisotropy as a recording / reproducing layer, and a second layer having perpendicular magnetic anisotropy as a recording auxiliary layer, and both layers are magnetically coupled. An overwritable multilayer magneto-optical recording medium capable of aligning the magnetization of the second layer either upward or downward without changing the direction of magnetization of the first layer. 6. When a high-level laser beam is applied, the “A direction” magnetization of the recording auxiliary layer is reversed to “reverse A direction” by the recording magnetic field, and the “reverse A direction” magnetization is applied to the recording / reproducing layer by the “reverse A direction” magnetization. When a bit having a “direction” magnetization (or “direction A” magnetization) is formed and a low level laser beam is applied, the “A direction” magnetization of the recording / reproducing layer is generated by the “direction A” magnetization of the recording auxiliary layer. 6. The overwritable multilayer magneto-optical recording medium according to claim 5, wherein a bit having [or "reverse A direction" magnetization] is formed. 7. The first layer is a magnetic thin film having a high coercive force and a low Curie point at room temperature, and the second layer is a magnetic thin film having a low coercive force and a high Curie point at a relatively room temperature. 6. An overwritable multilayer magneto-optical recording medium according to claim 5. 8. The following one condition: And the following four conditions at room temperature: 6. The overwritable magneto-optical recording medium according to claim 5, wherein H _C1 > H _D1 H _C2 > H _D2 H _C2 + H _D2 <| H ini. | <H _C1 ± H _D1 . However, T _R : room temperature T _C1 : Curie point of the first layer T _C2 : Curie point of the second layer T _L : Temperature of the recording medium when a low level laser beam is irradiated T _H : High level laser beam is irradiated Temperature of recording medium H _C1 : Coercive force of first layer H _C2 : Coercive force of second layer H _D1 : Coupling magnetic field H _D2 received by first layer: Coupling magnetic field Hini received by second layer: Initial auxiliary magnetic field 9. When the temperature at which the first layer is magnetically coupled to the second layer is T _S1 and the temperature at which the second layer is inverted by the recording magnetic field is T _S2 , the first layer has a high coercive force at room temperature, and the second layer has a high coercive force. 6. The overwritable magneto-optical recording medium according to claim 5, wherein the coercive force is relatively low at room temperature and T _S1 <T _S2 . 10. The following one condition: And the following four conditions at room temperature: 10. The overwritable magneto-optical recording medium according to claim 9, wherein H _C1 > H _D1 H _C2 > H _D2 H _C2 + H _D2 <| Hini. | <H _C1 ± H _D1 . However, T _R : room temperature T _S1 : temperature at which the first layer is magnetically coupled to the second layer T _S2 : temperature at which the second layer is inverted by the recording magnetic field T _L : temperature of the recording medium when a low-level laser beam is irradiated T _H: temperature H _C1 of the recording medium when irradiated with high-level laser beam: coercivity of first layer H _C2: second layer of a coercive force H _D1: first layer undergoes coupling field H _D2: second 10. Coupling magnetic field Hini. Received by layer: initial auxiliary magnetic field 6. The overwritable magneto-optical recording medium according to claim 5, wherein both the first layer and the second layer are selected from a transition metal-heavy rare earth alloy composition. 12. Transition metal-heavy rare earth alloy in which the first layer is heavy rare earth rich and has a compensation temperature between room temperature and Curie point; transition metal in which the second layer is heavy rare earth rich and has a compensation temperature between room temperature and Curie point- It is made of a heavy rare earth alloy and has the following conditional expression: And at room temperature the following conditional expressions: (2) H _C1 > H _C2 + σ _W / 2M _S1 t ₁ + σ _W / 2M _S2 t ₂ (3) H _C1 > σ _W / 2M _S1 t ₁ (4 12. The over according to claim 11, which satisfies the following condition: H _C2 > σ _W / 2M _S2 t ₂ (5) H _C2 + σ _W / 2M _S2 t ₂ <Hini. <H _C1 −σ _W / 2M _S1 t ₁ A writable magneto-optical recording medium. However, T _R : room temperature T _COMP.1 : compensation temperature of the first layer T _C1 : Curie point of the first layer T _C2 : Curie point of the second layer T _L : temperature of the recording medium when a low level laser beam is irradiated. T _H: temperature H _C1 of the recording medium when irradiated with high-level laser beam: coercivity of first layer H _C2: second layer of a coercive force M _S1: first layer of saturated magnetic moment M _S2: second 12. Saturation magnetic moment t _{1 of} layer: thickness t _{2 of} first layer: thickness σ _{W of} second layer: interface domain wall energy Hini .: initial auxiliary magnetic field Transition metal-heavy rare earth alloy in which the first layer is heavy rare earth rich and has no compensation temperature between room temperature and Curie point, transition metal in which the second layer is heavy rare earth rich and has compensation temperature between room temperature and Curie point -Consisting of a heavy rare earth alloy and having the following conditional expression: And at room temperature the following conditional expressions: (2) H _C1 > H _C2 + σ _W / 2M _S1 t ₁ + σ _W / 2M _S2 t ₂ (3) H _C1 > σ _W / 2M _S1 t ₁ (4 12. The over according to claim 11, which satisfies the following condition: H _C2 > σ _W / 2M _S2 t ₂ (5) H _C2 + σ _W / 2M _S2 t ₂ <Hini. <H _C1 −σ _W / 2M _S1 t ₁ A writable magneto-optical recording medium. However, T _R : room temperature T _C1 : Curie point of the first layer T _C2 : Curie point of the second layer T _L : Temperature of the recording medium when a low level laser beam is irradiated T _H : High level laser beam is irradiated Temperature of recording medium H _C1 : coercive force of first layer H _C2 : coercive force of second layer M _S1 : saturation magnetic moment of first layer M _S2 : saturation magnetic moment of second layer t ₁ : first layer 13. Thickness t _{2 of} the second layer: thickness σ _W of the second layer: interface domain wall energy Hini .: initial auxiliary magnetic field Transition metal-heavy rare earth alloy in which the first layer is heavy rare earth rich and has a compensation temperature between room temperature and Curie point, transition metal in which the second layer is heavy rare earth rich and has no compensation temperature between room temperature and Curie point -Consisting of a heavy rare earth alloy and having the following conditional expression: And at room temperature the following conditional expressions: (2) H _C1 > H _C2 + σ _W / 2M _S1 t ₁ + σ _W / 2M _S2 t ₂ (3) H _C1 > σ _W / 2M _S1 t ₁ (4 12. The over according to claim 11, which satisfies the following condition: H _C2 > σ _W / 2M _S2 t ₂ (5) H _C2 + σ _W / 2M _S2 t ₂ <Hini. <H _C1 −σ _W / 2M _S1 t ₁ A writable magneto-optical recording medium. However, T _R : room temperature T _COMP.1 : compensation temperature of the first layer T _C1 : Curie point of the first layer T _C2 : Curie point of the second layer T _L : temperature of the recording medium when a low level laser beam is irradiated. T _H: temperature H _C1 of the recording medium when irradiated with high-level laser beam: coercivity of first layer H _C2: second layer of a coercive force M _S1: first layer of saturated magnetic moment M _S2: second 14. Saturation magnetic moment t _{1 of} layer: thickness t _{2 of} first layer: thickness σ _{W of} second layer: interface domain wall energy Hini .: initial auxiliary magnetic field Transition metal-heavy rare earth alloy in which the first layer is heavy rare earth rich and has no compensation temperature between room temperature and Curie point, transition in which the second layer is heavy rare earth rich and has no compensation temperature between room temperature and Curie point It consists of a metal-heavy rare earth alloy and has the following conditional expression: And at room temperature the following conditional expressions: (2) H _C1 > H _C2 + σ _W / 2M _S1 t ₁ + σ _W / 2M _S2 t ₂ (3) H _C1 > σ _W / 2M _S1 t ₁ (4 12. The over according to claim 11, which satisfies the following condition: H _C2 > σ _W / 2M _S2 t ₂ (5) H _C2 + σ _W / 2M _S2 t ₂ <Hini. <H _C1 −σ _W / 2M _S1 t ₁ A writable magneto-optical recording medium. However, T _R : room temperature T _C1 : Curie point of the first layer T _C2 : Curie point of the second layer T _L : Temperature of the recording medium when a low level laser beam is irradiated T _H : High level laser beam is irradiated Temperature of recording medium H _C1 : coercive force of first layer H _C2 : coercive force of second layer M _S1 : saturation magnetic moment of first layer M _S2 : saturation magnetic moment of second layer t ₁ : first layer 15. film thickness t ₂ : second layer thickness σ _W : interface domain wall energy Hini .: initial auxiliary magnetic field Transition metal-heavy rare earth alloy in which the first layer is rich in heavy rare earth and has a compensation temperature between room temperature and the Curie point, and transition metal in which the second layer is rich in transition metal and has no compensation temperature between room temperature and the Curie point -Consisting of a heavy rare earth alloy and having the following conditional expression: Satisfied, and each of the following conditional expressions at room _{temperature: (2) H C1> H} C2 + | σ W / 2M S1 t 1 -σ W / 2M S2 t 2 | (3) H C1> σ W / 2M S1 Claim 11 which satisfies t ₁ (4) H _C2 > σ _W / 2M _S2 t ₂ (5) H _C2 + σ _W / 2M _S2 t ₂ <Hini. <H _C1 + σ _W / 2M _S1 t _1. An overwritable magneto-optical recording medium according to claim 1. However, T _R : room temperature T _COMP.1 : compensation temperature of the first layer T _C1 : Curie point of the first layer T _C2 : Curie point of the second layer T _L : temperature of the recording medium when a low level laser beam is irradiated. T _H: temperature H _C1 of the recording medium when irradiated with high-level laser beam: coercivity of first layer H _C2: second layer of a coercive force M _S1: first layer of saturated magnetic moment M _S2: second 16. Saturation magnetic moment t _{1 of} layer: thickness t _{2 of} first layer: thickness σ _{W of} second layer: interface domain wall energy Hini .: initial auxiliary magnetic field Transition metal-heavy rare earth alloy in which the first layer is heavy rare earth rich and has no compensation temperature between room temperature and the Curie point, transition in which the second layer is transition metal rich and has no compensation temperature between room temperature and the Curie point It consists of a metal-heavy rare earth alloy and has the following conditional expression: Satisfied, and each of the following conditional expressions at room _{temperature: (2) H C1> H} C2 + | σ W / 2M S1 t 1 -σ W / 2M S2 t 2 | (3) H C1> σ W / 2M S1 Claim 11 which satisfies t ₁ (4) H _C2 > σ _W / 2M _S2 t ₂ (5) H _C2 + σ _W / 2M _S2 t ₂ <Hini. <H _C1 + σ _W / 2M _S1 t _1. An overwritable magneto-optical recording medium according to claim 1. However, T _R : room temperature T _C1 : Curie point of the first layer T _C2 : Curie point of the second layer T _L : Temperature of the recording medium when a low level laser beam is irradiated T _H : High level laser beam is irradiated Temperature of recording medium H _C1 : coercive force of first layer H _C2 : coercive force of second layer M _S1 : saturation magnetic moment of first layer M _S2 : saturation magnetic moment of second layer t ₁ : first layer 17. Thickness t _{2 of} the second layer: thickness σ _W of the second layer: interface domain wall energy Hini .: initial auxiliary magnetic field Transition metal-heavy rare earth alloy in which the first layer is transition metal rich and has no compensation temperature between room temperature and Curie point, and the transition layer is transition metal rich where there is no compensation temperature between room temperature and Curie point. It consists of a metal-heavy rare earth alloy and has the following conditional expression: And at room temperature the following conditional expressions: (2) H _C1 > H _C2 + σ _W / 2M _S1 t ₁ + σ _W / 2M _S2 t ₂ (3) H _C1 > σ _W / 2M _S1 t ₁ (4 12. The over according to claim 11, which satisfies the following condition: H _C2 > σ _W / 2M _S2 t ₂ (5) H _C2 + σ _W / 2M _S2 t ₂ <Hini. <H _C1 −σ _W / 2M _S1 t ₁ A writable magneto-optical recording medium. However, T _R : room temperature T _C1 : Curie point of the first layer T _C2 : Curie point of the second layer T _L : Temperature of the recording medium when a low level laser beam is irradiated T _H : High level laser beam is irradiated Temperature of recording medium H _C1 : coercive force of first layer H _C2 : coercive force of second layer M _S1 : saturation magnetic moment of first layer M _S2 : saturation magnetic moment of second layer t ₁ : first layer 18. Film thickness t ₂ : Second layer thickness σ _W : Interface domain wall energy Hini .: Initial auxiliary magnetic field Transition metal-heavy rare earth alloy in which the first layer is transition metal rich and does not have a compensation temperature between room temperature and the Curie point; transition metal in which the second layer is heavy rare earth rich and has a compensation temperature between room temperature and the Curie point -Consisting of a heavy rare earth alloy and having the following conditional expression: Satisfied, and each of the following conditional expressions at room _{temperature: (2) H C1> H} C2 + | σ W / 2M S1 t 1 -σ W / 2M S2 t 2 | (3) H C1> σ W / 2M S1 Claim 11 which satisfies t ₁ (4) H _C2 > σ _W / 2M _S2 t ₂ (5) H _C2 + σ _W / 2M _S2 t ₂ <Hini. <H _C1 + σ _W / 2M _S1 t _1. An overwritable magneto-optical recording medium according to claim 1. However, T _R : room temperature T _C1 : Curie point of the first layer T _C2 : Curie point of the second layer T _L : Temperature of the recording medium when a low level laser beam is irradiated T _H : High level laser beam is irradiated Temperature of recording medium H _C1 : coercive force of first layer H _C2 : coercive force of second layer M _S1 : saturation magnetic moment of first layer M _S2 : saturation magnetic moment of second layer t ₁ : first layer Thickness t ₂ : thickness of second layer σ _w : interface domain wall energy Hini .: initial auxiliary magnetic field A transition metal-heavy rare earth alloy in which the first layer is rich in transition metal and has no compensation temperature between room temperature and the Curie point, and a transition in which the second layer is rich in heavy rare earth and has no compensation temperature between room temperature and the Curie point It consists of a metal-heavy rare earth alloy and has the following conditional expression: Satisfied, and each of the following conditional expressions at room _{temperature: (2) H C1> H} C2 + | σ W / 2M S1 t 1 -σ W / 2M S2 t 2 | (3) H C1> σ W / 2M S1 Claim 11 which satisfies t ₁ (4) H _C2 > σ _W / 2M _S2 t ₂ (5) H _C2 + σ _W / 2M _S2 t ₂ <Hini. <H _C1 + σ _W / 2M _S1 t _1. An overwritable magneto-optical recording medium according to claim 1. However, T _R : room temperature T _C1 : Curie point of the first layer T _C2 : Curie point of the second layer T _L : Temperature of the recording medium when a low level laser beam is irradiated T _H : High level laser beam is irradiated Temperature of recording medium H _C1 : coercive force of first layer H _C2 : coercive force of second layer M _S1 : saturation magnetic moment of first layer M _S2 : saturation magnetic moment of second layer t ₁ : first layer 21. The film thickness t _{2 of} the second layer: the film thickness of the second layer σ _W : the interface domain wall energy Hini. At room temperature, the following conditional expressions: (1) H _C1 > H _C2 + σ _W / 2M _S1 t ₁ + σ _W / 2M _S2 t ₂ (2) H _C1 > σ _W / 2M _S1 t ₁ (3) H _C2 > σ 6. The overwritable magneto-optical recording medium according to claim 5, which satisfies _W / 2M _S2 t ₂ . Where H _C1 : coercive force of the first layer H _C2 : coercive force of the second layer M _S1 : saturation magnetic moment of the first layer M _S2 : saturation magnetic moment of the second layer t ₁ : film thickness t of the first layer ₂ : thickness of the second layer σ _W : interface domain wall energy At room temperature, the following conditional expressions: (1) H _C1 > H _C2 + | σ _W / 2M _S1 t ₁ −σ _W / 2M _S2 t ₂ | (2) H _C1 > σ _W / 2M _S1 t ₁ (3) 6. The overwritable magneto-optical recording medium according to claim 5, wherein H _C2 > σ _W / 2M _S2 t ₂ is satisfied. Where H _C1 : coercive force of the first layer H _C2 : coercive force of the second layer M _S1 : saturation magnetic moment of the first layer M _S2 : saturation magnetic moment of the second layer t ₁ : film thickness t of the first layer ₂ : thickness of the second layer σ _W : interface domain wall energy The following conditions are satisfied: (1) T _R <T _C1 <T _C2 , and at room temperature the following conditions: (2) H _C1 > H _C2 + σ _W / 2M _S1 t ₁ + σ _W / 2M _S2 t _{2 (3) H C1> σ} W / 2M S1 t 1 (4) H C2> σ W / 2M S2 overwritable magneto-optical recording medium of the fifth term recited in the claims which satisfies t _2. Where: T _R : room temperature T _C1 : Curie point of the first layer T _C2 : Curie point of the second layer H _C1 : Coercive force of the first layer H _C2 : Coercive force of the second layer M _S1 : Saturation of the first layer 23. Magnetic moment M _S2 : Saturation magnetic moment of the second layer t ₁ : Film thickness of the first layer t ₂ : Film thickness of the second layer σ _W : Interface domain wall energy The following conditional expressions: (1) T _R <T _C1 <T _C2 is satisfied, and the following conditional expressions are satisfied at room temperature: (2) H _C1 > H _C2 + | σ _W / 2M _S1 t ₁ −σ _W / The overwritable magneto-optical recording according to claim 5, wherein 2M _S2 t ₂ | (3) H _C1 > σ _W / 2M _S1 t ₁ (4) H _C2 > σ _W / 2M _S2 t ₂ is satisfied. Medium. Where: T _R : room temperature T _C1 : Curie point of the first layer T _C2 : Curie point of the second layer H _C1 : Coercive force of the first layer H _C2 : Coercive force of the second layer M _S1 : Saturation of the first layer Magnetic moment M _S2 : Saturation magnetic moment of the second layer t ₁ : Film thickness of the first layer t ₂ : Film thickness of the second layer σ _W : Interfacial domain wall energy 25. At room temperature, the following conditional expressions: (1) H _C1 > H _C2 + σ _W / 2M _S1 t ₁ + σ _W / 2M _S2 t ₂ or H _C1 > H _C2 + | σ _W / 2M _S1 t ₁ −σ _W / 2M _{S2 t 2 |. (2)} H C1> σ W / 2M S1 t 1 (3) H C2> σ W / 2M S2 t 2 (4) H C2 + σ W / 2M S2 t 2 <Hini <H C1 + σ W The overwritable magneto-optical recording medium according to claim 5, wherein the medium satisfies / 2M _S1 t ₁ . Where H _C1 : coercive force of the first layer H _C2 : coercive force of the second layer M _S1 : saturation magnetic moment of the first layer M _S2 : saturation magnetic moment of the second layer t ₁ : film thickness t of the first layer ₂ : film thickness σ _{W of} second layer: interface domain wall energy Hini .: initial auxiliary magnetic field In the magneto-optical recording device, the device comprises: (a) at least a first layer having perpendicular magnetic anisotropy as a recording / reproducing layer and a second layer having perpendicular magnetic anisotropy as a recording auxiliary layer. Means for moving a multi-layer magneto-optical recording medium comprising a layer and a Curie point of the second layer higher than the Curie point of the first layer; (b) a laser beam light source; (C) a beam intensity according to the binary information to be recorded. Means for pulse-modulating between (1) a high level that raises the temperature of the medium near the Curie point of the second layer and (2) a low level that raises the temperature of the medium near the Curie point of the first layer; A) a recording magnetic field applying means which is in the vicinity of the beam irradiation position and does not modulate the magnetic field; 27. There is a multilayer magneto-optical recording medium in which the first layer having perpendicular magnetic anisotropy is a recording / reproducing layer, the second layer having perpendicular magnetic anisotropy is a recording auxiliary layer, and the Curie point of the second layer is higher than that of the first layer. Between: (1) a high level that raises the temperature of the medium near the Curie point of the second layer; and (2) a low level that raises the temperature of the medium near the Curie point of the first layer. Modulator that pulse modulates beam intensity. 28. (1) a high level that gives the magneto-optical recording medium the temperature required to form one of the bit having the upward magnetization and the bit having the downward magnetization, and (2) the other bit before recording. A modulation method for pulse-modulating a laser beam between a low level that gives a temperature necessary for forming the medium irrespective of a bit type to the medium. 29. There is a multilayer magneto-optical recording medium in which the first layer having perpendicular magnetic anisotropy is a recording / reproducing layer, the second layer having perpendicular magnetic anisotropy is a recording auxiliary layer, and the Curie point of the second layer is higher than that of the first layer. Between: (1) a high level that raises the temperature of the medium near the Curie point of the second layer; and (2) a low level that raises the temperature of the medium near the Curie point of the first layer. A modulation method for pulse-modulating the beam intensity. 30. At least two layers, a first layer and a second layer, are magnetically coupled to each other, and the magnetization of the second layer is obtained by the following equation H _C2 + H _D2 < | Hini. | <H _C1 + H _D1 . A magneto-optical recording medium which can be aligned in one direction by a magnetic field Hini. Having a magnitude of H _C1 + H _D1 , wherein information is already recorded in the first layer. Here, H _C1 : coercive force of the first layer H _C2 : coercive force of the second layer H _D1 : coupling magnetic field received by the first layer H _D2 : coupling magnetic field received by the second layer Made from the second layer laminated thereto at least a first _{layer, (1) H C1> σ} W / 2M S1 t 1 (2) H C2> σ W / 2M S2 t 2 (3) T R <T C1 < magneto-optical recording medium which satisfies T _C2. Where H _C1 : coercive force of the first layer H _C2 : coercive force of the second layer M _S1 : saturation magnetic moment of the first layer M _S2 : saturation magnetic moment of the second layer t ₁ : film thickness t of the first layer ₂ : film thickness of the second layer T _R : room temperature T _C1 : Curie point of the first layer T _C2 : Curie point of the second layer σ _W : interfacial domain wall energy between the first and second layers 6. The magneto-optical recording medium according to claim 5, wherein said magnetic coupling is exchange coupling.