JP3353354B2 - Magneto-optical recording medium and magneto-optical recording method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical recording medium in which magneto-optical (thermal) magnetic recording is performed on a perpendicular magnetization film by irradiating a spot such as a laser beam, and reading of the recording is performed by detecting a Kerr rotation angle. It relates to the magnetic recording system.

[0002]

2. Description of the Related Art In a magneto-optical recording medium in which information pits or magnetic domains are formed by local heating by laser beam irradiation and are read out by magneto-optical interaction, so-called Kerr effect, a magnetic layer for recording and reproducing is, for example, disk-shaped. The tracking servo signal and the address signal are formed on a transparent substrate, and are formed as uneven grooves or phase pits on the transparent substrate so that tracking servo or the like is performed.

As described above, in the conventional magneto-optical recording medium, unevenness corresponding to the servo signal is provided at a fine pitch on the transparent substrate. Therefore, when a material having excellent mechanical properties such as a glass substrate is used, the It is necessary to use 2P (photopolymer) or the like for the formation, and there is a problem that the cost is increased. For this reason, conventionally, an injection-molded substrate made of polycarbonate or the like, whose mechanical properties are relatively inferior, is used, and it is not possible to avoid surface runout and the like, which places a heavy burden on a servo system such as a focus servo.

Further, since signals for tracking servo are formed in a device separate from the recording / reproducing drive device, if eccentricity occurs, a large load is imposed on the servo system due to the high-speed rotation of the disk. There is a problem that it is unavoidable to apply.

Further, when a tracking servo signal, an address signal or sector information is formed as an uneven groove or pit on a substrate, a defect is likely to occur, and the shape of the signal is the quality of a tracking signal or a magneto-optical signal, that is, S / S. N (signal-to-noise ratio) and modulation degree are easily affected.
The process of forming the irregularities is a factor that lowers the yield of the medium.

On the other hand, for example, Japanese Patent Application Laid-Open No. 56-6103
Japanese Patent Laid-Open Publication No. 1 (1999) -1995 discloses a configuration in which a perpendicular magnetization film is locally crystallized in place of a groove to eliminate magnetic anisotropy and provide an in-plane magnetization film, thereby forming a servo signal and an address signal. For example, Japanese Patent Laid-Open Publication No.
Japanese Patent Publication No. 132 proposes a method in which an amorphous ferrimagnetic thin film is formed on a substrate, and guide track signals and the like are crystallized in advance, for example, in a pit shape.

However, in the case of these structures, a high-power laser is required for crystallization and rewriting is impossible, so that the process of forming servo and address signals similarly reduces the yield of the medium. There is a problem that it is affected, and at present it is not used practically.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a magneto-optical recording medium or a magneto-optical recording system, as described above, in which a material having a low cost and excellent mechanical strength can be obtained by increasing the degree of freedom in selecting a material for a transparent substrate. An object of the present invention is to enable application, to reduce costs and to reduce the load on a servo system.

According to the present invention, at least a first perpendicular magnetization film, a cutting layer, a second perpendicular magnetization film, and a heat conduction film are sequentially formed on a flat transparent substrate, and a nonmagnetic layer or in-plane magnetization is formed as a cutting layer. A thermal conductive film made of a material having a higher thermal conductivity than the thermal conductivity of the first and second perpendicular magnetic films, and the Curie temperature of the first and second perpendicular magnetic films is set to Tc, respectively.
_When Tc ₁ and Tc ₂ are set, Tc ₁ <Tc ₂ is set so that recording or erasing is performed on the first perpendicular magnetic film without destroying the tracking servo signal recorded on the second perpendicular magnetic film.

Further, according to the present invention, in the above-mentioned magneto-optical recording medium, at least the first perpendicular magnetic film, the second perpendicular magnetic film, and the heat conductive film are formed by a vacuum thin film forming method.

Further, according to the present invention, in each of the above-described magneto-optical recording media, the recording start powers of the first and second perpendicular magnetic films are Pth ₁ and Pth ₂ , respectively, and the optimum recording powers are Prec ₁ and Prec ₂ , respectively. When the read power is Pread, a laser of power Prec ₂ that satisfies Prec ₂ > Pth ₂ is applied to record a tracking servo signal, and then, under a recording magnetic field Hrec, Pth ₂ > Prec ₁ > Pth ₁ > A configuration is adopted in which recording and erasing are performed by irradiating a laser having a recording and erasing power Prec ₁ that satisfies Pread.

Further, according to the present invention, in the above-mentioned magneto-optical recording medium, the thickness of the first perpendicular magnetization film is set to 100 ° or more and 6 ° or more.
It is configured as 00 ° or less.

According to the magneto-optical recording method of the present invention, at least a first perpendicular magnetic film, a cutting layer, and a second perpendicular magnetic film having a Curie temperature different from that of the first perpendicular magnetic film are formed on a flat transparent substrate. And a laser power for recording or erasing data using a magneto-optical recording medium on which a thermal conductive film having a higher thermal conductivity than the thermal conductivity of the first and second perpendicular magnetic films is formed. A preformat signal including a tracking servo signal is previously recorded on the first or second perpendicular magnetization film having a relatively higher laser power and a relatively higher Curie temperature.

Further, according to the present invention, in the above-described magneto-optical recording system, when pre-format signals are recorded in advance, the magneto-optical recording medium is fixed in a state of being chucked by a spindle motor, and this spindle motor is rotated by spindle chucking means. The pre-format signal is recorded by mounting it on a pre-format signal recording-dedicated magneto-optical recording device, and thereafter the eccentricity is set to 0 μm or more and 10 μm or less by incorporating the magneto-optical recording medium with the spindle motor in the magneto-optical recording device. Further, according to the present invention, in the above-described magneto-optical recording method, when a pre-format signal is recorded in advance, a magneto-optical recording medium is fixed in a state where it is chucked by a spindle motor, and the spindle motor is pre-formatted by a spindle chucking means. The eccentricity is set to 0 μm or more and 10 μm or less by mounting the optical recording device in a magneto-optical recording device having a function of recording a preformat signal and recording a preformat signal. Furthermore, the present invention, in the above-described magneto-optical recording method, when pre-recording a preformat signal, fixing a boss made of a metal disk at the center of the magneto-optical recording medium,
By fitting this boss to the spindle motor shaft, the eccentricity of the magneto-optical recording medium to the spindle motor is reduced to 0 μm.
A chucking means for chucking with a thickness of 10 μm or less is used.

[0015]

[0016]

[0017]

As described above, the present invention uses a flat transparent substrate 2 having no irregularities such as grooves or pits as shown in FIG. 1 and the second vertical magnetic film 3 ₁ and 3 ₂
Are stacked and provided by using a difference in Curie temperature to a perpendicular magnetic film having a relatively high Curie temperature at least with a laser power relatively higher than the laser power for recording or erasing data. By applying the magneto-optical recording method of the present invention in which a preformat signal including a tracking servo signal is recorded in advance, the process of forming an uneven groove or pit on a substrate can be omitted.

For this reason, it is possible to use a transparent substrate material such as a glass substrate which is relatively inexpensive and has excellent mechanical strength, so that the cost can be reduced and the load on the servo system can be reduced. Can be improved.

[0019] In the above magneto-optical recording medium and magneto-optical recording method, more of the non-magnetic layer as the cutting layer to the first and second between the vertical magnetization film 3 ₁ and 3 ₂ laminated magneto-optical recording medium or by providing the in-plane magnetization film, since it is possible to reduce the as described in detail in subsequent embodiments, the first and second magnetic wall energy of the perpendicular magnetization film 3 ₁ and 3 _2, preformat A good S / S is obtained without being affected by the perpendicular magnetization film on which the signal is written.
Recording and reproduction of information signals can be performed with the N ratio.

Further, in the above-described magneto-optical recording medium, the thickness of the _first perpendicular magnetic film 31 is set to 100 ° or more and 600 ° or more.
By configuring as Å or less, as well as described in detail in subsequent embodiments, the first and second vertical magnetic film 3 ₁ and 3 ₂ of the side, in particular away from the substrate 1 of the magnetic film 3 ₂ The degree of modulation of the magnetization state can be made sufficiently large.

Further, by providing the heat conducting film 5 having a higher thermal conductivity in proximity to the two perpendicular magnetization films 3 ₁ and / or 3 ₂ , as will be described in detail in a later embodiment. By increasing the difference between the reproduction threshold powers of the perpendicular magnetization films 3 ₁ and 3 ₂ , the so-called power margin can be increased, and recording and reproduction can be performed with a good S / N ratio.

Further, in the above-described magneto-optical recording method, by recording the preformat signal and the information signal in the same apparatus, the tracking servo signal and the address signal can be written without causing eccentricity. Thus, the load on the servo system can be reduced.

In the above-described magneto-optical recording method, a pre-format signal is recorded in advance using a magneto-optical recording device dedicated for recording a pre-format signal, and information signals are recorded and reproduced using a normal magneto-optical recording device. By using the chucking means having an eccentricity of 10 μm or less, the load on the servo system can be reduced.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a magneto-optical recording medium and a magneto-optical recording system according to the present invention will be described below in detail. In this example, a case where the present invention is applied to a magnetic field modulation type magneto-optical recording medium and method is shown as an example.

As shown in FIG. 1, a disk-shaped (disk-shaped) transparent substrate 1 made of glass or the like having a surface entirely flat including a servo zone, ie, having no irregularities such as phase pits and groove grooves. above, the first dielectric film 2 _1, the first vertical magnetic film 3 _1, second dielectric layer 2 _2, the second vertical magnetic film 3, _second and third dielectric films 2 _3, thermal conductivity The magneto-optical recording medium 10 is formed by sequentially laminating the films 5 by a vacuum thin film forming method.

In the magneto-optical recording medium 10 having such a configuration,
And the first and second perpendicular magnetization films 3 ₁And 3_TwoCurie
-Temperature is Tc₁, Tc_TwoThen, Tc_Two> Tc₁ The material is selected so as to satisfy the condition of ‥‥‥ (1), and each magnetic film is selected.
Recording start power of Pth₁And Pth_Two, Each magnetization
The optimum recording power of the film₁, Prec_TwoAnd then
When the read power is Pread,_Two> Pth_Two ‥‥‥ (2) Irradiate the laser with power of_TwoTo
After recording the tracking servo signal, the recording magnetic field Hre
Under c, Pth_Two> Prec₁> Pth₁> Pread 記録 (3)₁By adopting
Second perpendicular magnetization film 3_TwoTracking servo recorded on
First perpendicular magnetization film 3 without destroying the application signal₁Recorded in
Alternatively, erasure can be performed.

[0027] Specifically, as the first vertical magnetic film _{3 1, Tb 0.185 (Fe 0.95} Co 0.05) 0.815, Tc 1 =
Using 180 ° C. material, as the second vertical magnetic film 3 _2,
(Gd _0.83 Tb _0.17 ) _0.205 (Fe _0.70 Co _0.30 )
_0.795, with Tc ₂ = 360 ° C. of the material, the first vertical magnetic film 3 ₁ having a thickness of, for example 100 Å, the second vertical magnetic film 3 _{and second} film thickness not less than, for example, 100 Å 50 Å, also for example, SiN the dielectric film 2 ₁ consisting of _x, 2 ₂ and 2 ₃ of a thickness of respectively 1100 Å, 400 Å, and 800 Å, a
When the thickness of the heat conductive film 5 made of l or the like is 550 °,
Pth ₁ and Pth _{2 at a} linear velocity of 10 m / s are each 4 m
W, 8.5 mW, and Pread is 1.5 mW,
Equations (1), (2), and (3) described above can be satisfied. That is, 360 ° C.> 180 ° C. (1 ′) Prec ₂ > 8.5 mW ‥‥‥ (2 ′) 8.5 mW> Prec ₁ > 4 mW> 1.5 mWＷ (3 ′). In this case, a second signal recorded in the perpendicular magnetic film 3 ₂ could be reproduced at about approximately 2/3 of the intensity of the first signal recorded on the perpendicular magnetic film 3 _1.

The laminated structure of each film and the material and thickness of each layer shown here can be variously modified and changed.
The above-described first perpendicular magnetization film 3 _{1 having} a relatively low Curie temperature.
Is Tb _x (Fe _{1 -z} Co _z ) _{1 -x} , x,
The range of z may be 0.1 ≦ x ≦ 0.30 ≦ z ≦ 0.4. Moreover, the relatively Curie temperature high second composition of the perpendicular magnetic film _{3 2, (Gd y Tb 1} -y) x (Fe
_1-z Co _z ) _{Assuming 1-x} , the ranges of x, y, and z may be 0.1 ≦ x ≦ 0.30 ≦ y ≦ 0.95 0.1 ≦ z ≦ 1.

As the magnetic material, a known rare earth element may be used.
Any of transition metal amorphous materials may be used, and Cr, Ti, or the like may be added to these as an additional element.

Further the magnetic film 3 ₁ and 3 ₂ are magnetized film of a different composition can also be a plurality of layers stacked configuration, the second vertical magnetic film 3 _2, as described above as a total thickness About 50 ° or more. The thickness of the first vertical magnetic film 3 ₁ will be described in detail later. Further, it is desirable that the difference between the Curie temperatures of the respective magnetic films 3 ₁ and 3 ₂ is at least 50 ° C. or more, and that the Curie temperatures of the first and second perpendicular magnetic films 3 ₁ and 3 ₂ are reversed. Conversely, it is also possible to select and configure.

[0031] Furthermore Zn as a dielectric film 2 ₁ to 2 ₃
Other dielectric materials such as S and AlN may be used, and it is needless to say that similar modifications can be made even in the following examples unless otherwise described.

FIGS. 2 and 3 show typical magnetization modes when the information signal and the tracking servo signal are recorded in this manner. First, a magnetized film having a relatively high power and at least a relatively high Curie temperature, in this case, the first and second magnetic films.
Tracking the perpendicular magnetization film 3 ₁ and 3 ₂ servo signal 9
To form FIG. 2 shows the magnetization mode of the data zone. In this case, the first perpendicular magnetization film 3 _{1 having} a relatively low Curie temperature is used.
The information signal is recorded only in the. Then, as shown in FIG. 3, in the pre-format signal zone, in this case pre-format signal of the address signal or the like to both magnetization film 3 ₁ and 3 ₂ are recorded includes a second perpendicular magnetic film 3 _2.

As described above, a signal corresponding to a pre-groove in a conventional magneto-optical recording medium is recorded as a signal for tracking servo, and tracking servo can be applied by a push-pull method.

The signal processing method according to the present invention will be described with reference to FIG. This case differs from the conventional magneto-optical recording system in that the tracking servo signal is obtained from the magneto-optical signal. A light spot is emitted from a light source 31 such as a semiconductor laser to the magneto-optical recording medium 10 via a half mirror 32 and an objective lens 33. The signal read therefrom is reflected by the half mirror 31 and separated by another half mirror 34. Then, each signal is analyzed by the analyzer 3.
Photodetectors 36a, 36b via 5a, 35b
And the signals a, b, c, d, e, f, g, h
Get. And subtracters 37a, 37b, 37c and 37
According to d, A = ae, B = bf, C = cg, D =
d-h, and adders 38a and 38
(b) The tracking error signal 40 can be obtained by calculating the signal of (A + D)-(B + C) using the subtractor 39.

When a conventional push-pull method using a medium having a pre-groove is used, a signal (a + d)-(b + c) is obtained by one photodetector and used for tracking servo.

It is needless to say that other wobbling signals can be used as the servo signals.

[0037] In the present invention method as described above, it is necessary to perform recording and erasing to the vertical magnetization film 3 ₁ and 3 ₂ relatively with a low laser power of the first and second relatively high laser power. By recording a preformat signal and an information signal using a magneto-optical recording device equipped with such a laser, the preformat signal and the information signal are formed substantially concentrically without eccentricity with each other, and the servo The load on the system can be reduced, and both the tracking servo band and the focus servo band can be suppressed to about 1/2.

In addition, when a preformat signal is recorded in advance by using a magneto-optical recording device exclusively for recording preformat signals and an information signal is recorded and reproduced using a normal magneto-optical recording device, the eccentricity becomes 10 μm or less. By using the chucking means, the load on the focus servo system can be similarly reduced, and in this case, both the tracking servo band and the focus servo band can be suppressed to about 1/2. Each example of such a chucking means will be described with reference to FIGS.

First, FIG. 5 is a schematic diagram of a magneto-optical recording apparatus dedicated to preformat signal recording. Magneto-optical recording medium 10
Is fixed in a state where it is chucked to the spindle motor 21. The spindle motor 21 is chucked by the spindle motor chucking means 22 and mounted on the apparatus.
Recording of an address signal and the like and a groove portion is performed. In this case, the eccentricity can be reduced to almost zero by moving the pickup 23 for recording the preformat signal such as the tracking servo signal with very high accuracy and then incorporating the spindle motor into the recording / reproducing apparatus.

By providing such a function in the recording / reproducing apparatus itself, it is possible to record a preformat signal such as a tracking signal after the medium 10 is incorporated.

As shown in FIG. 6, a hub used in a normal magneto-optical recording medium has both processing accuracy and mounting accuracy, as is performed with a so-called hard disk in which a medium is fixedly mounted in an apparatus. By using a so-called boss capable of performing attachment with very high accuracy while suppressing eccentricity, it is possible to configure the chucking means 25 having eccentricity of 10 μm or less.

In this case, the boss 26 made of a metal disk or the like is used.
Is fixed to the center of the magneto-optical recording medium 10 by bonding or screwing. The inner diameter of the aperture 26a provided at the center of the boss is formed so as to be substantially equal to the outer diameter of the shaft of the spindle motor on which the magneto-optical recording medium 10 is mounted, so that play does not occur. It is fitted without. Thereby, the eccentricity can be suppressed to 10 μm or less. This is the amount of eccentricity 4 in the conventional magneto-optical recording medium.
This corresponds to about ４ to ５ of 0 to 50 μm.

Further, by using a glass substrate as a material for the transparent substrate 1 instead of a resin such as a conventionally used PC, it is possible to suppress the surface runout, that is, the displacement from the reference surface of the disk to about 1/10. it can.

It is needless to say that the present invention is not limited to the above-mentioned chucking means, but may adopt various other structures capable of suppressing the amount of eccentricity to about 10 μm or less.

Next, in the magneto-optical recording medium 1 described above,
A second dielectric film 2 ₂ between the first and second vertical magnetic film 3 ₁ and 3 ₂ and magnetic interaction acting on respective perpendicular magnetization film, i.e. the exchange coupling and magnetostatic coupling small The operation and effect when a cutting layer such as a non-magnetic layer and an in-plane magnetized film that can be provided will be described below.

In this case, as shown in FIG.
During the vertical magnetization film 3 ₁ and 3 _2, instead of the dielectric film F of
The cutting layer 4 was provided using an in-plane magnetized film of e _0.7 Co _0.3 or the like, and the material and thickness of the other films were selected in the same manner as in the example described in FIG. T that is, the first vertical magnetic film 3 ₁ by _{Tb 0.185 (Fe 0.95 Co 0.05)} 0.815
As c ₁ = 180 ℃, the second vertical magnetic film 3 ₂ (Gd
_{0.83 Tb 0.17) 0.205 (Fe 0.70} Co 0.30) 0.795 by the Tc ₂ = 360 ° C., also the first and third such SiN _X dielectric film 2 ₁ and 2 ₃ and the thickness, respectively 11
00 ° and 800 °, and the thickness of the heat conductive film 5 of Al or the like is 5
The magneto-optical recording medium was formed at 50 °.

[0047] In such a configuration, to measure the change in the interface wall energy between the perpendicular magnetization film 3 ₁ and 3 ₂ film of each of the first and second to the thickness of the cutting layer. This result is shown in FIG.
Shown in From this figure, it is understood that the domain wall energy can be made almost zero by setting the thickness of the cutting layer to about 50 °.

Based on the results, the thickness of the cut layer was set to 40 °
As for other configurations, a magneto-optical recording medium selected in the same manner as in the above-described embodiment was manufactured, and information was recorded.
Second good S without being affected by the perpendicular magnetic film 3 ₂
/ N could be recorded.

Also in this case, the constitutions of the first and second perpendicular magnetization films can be reversed, and the material composition can be changed within the above-mentioned range. Metal or non-magnetic layer such as Al, C
u, a metal such as Ti, magnetic interaction i.e. exchange coupling exerted between the magnetic film 3 ₁ and 3 _2, it is possible to use other materials to reduce the magnetostatic coupling.

[0050] Furthermore, as shown in FIG. 9, without particularly providing the film as a cutting layer, the first predetermined time left after depositing a perpendicular magnetization film 3 _1, then the second vertical magnetic film 3 ₂ , it is also possible to configure the switching layer by a second dielectric film 2 ₂ and thermal conductivity film is provided, to alter the first vertical magnetic film 3 _first surface. In this case, each of the first and second vertical magnetic film 3 ₁ and 3 _2, the first and third dielectric films 2 ₁
And 2 _3, the thickness and material of the heat conductive film 5 is selected similarly to the example described in FIG. 1 described above, the vacuum thin film forming method on the substrate 1 first dielectric film 2 ₁ and the first the perpendicular magnetization film 3 ₁ deposited form, then after the time t (sec) left in the vacuum chamber, the second vertical magnetic film 3 _2, the second dielectric film 2 ₃ and thermal conductivity film 5 formed and films were measured the change in the interface wall energy between the first and second vertical magnetic film 3 ₁ and 3 ₂ for each standing time. This result is shown in FIG.
0 is shown. From this result, it is understood that the domain wall energy can be made almost zero by setting the leaving time t to about 100 sec.

Based on the result, the leaving time t is set to 100 seconds.
forming a magneto-optical recording medium 10 as ec, was subjected to recording of information signals, it was possible to perform recording without being affected by the second perpendicular magnetic film 3 _2.

In this example, the case where no film is provided as the cutting layer is shown, but the first and second perpendicular magnetization films 3 _{1 are used.}
And 3 to _second interface H ₂ O, or is adsorbed N _2, CO ₂ gas, such as by oxidizing the first vertical magnetic film 3 _first surface by introducing O ₂ gas, first and second In the case where the interface between the _two perpendicular magnetization films 3 ₁ and 3 ₂ is altered by a chemical change, the magnetic interaction can be similarly reduced, which corresponds to the configuration in which the cutting layer is provided in the present invention.

[0053] In this case, Toka providing the first and second vertical magnetic film 3 ₁ and 3 ₂ Conversely, also can be configured to change its composition as described above, also the magnetic layer material Any of the known rare earth-transition metal amorphous materials may be used, and Cr and Ti may be added as additional elements.

Next, referring to FIG. 1, FIG. 7 and FIG.
Each configuration of the magneto-optical recording medium 10 described above is adopted, and each
In this case, the first perpendicular magnetization of the magnetized film which is close to the transparent substrate 1
Membrane 3 ₁Perpendicular magnetization film 3 when the film thickness is changed_Two
Magnetization directions (ie, upward and downward toward the read side)
The change of the signal intensity of the above-mentioned (i) was measured. In each case, the first and
Second perpendicular magnetization film 3₁And 3_TwoIs the same as the above example
Like Tb_0.185(Fe _0.95Co_0.05)_0.815, (Gd
_0.83Tb_0.17)_0.205(Fe_0.70Co_0.30)_{0.79 Five}For
Each dielectric film
To SiN_X, The heat conductive film is made of Al, and the heat conductive film
The magneto-optical recording medium was constructed by setting the thickness of No. 5 to 550 °.

First, the configuration described with reference to FIG.
And the first to third dielectric films 2₁~ 2 _ThreeFilm thickness of 110
FIG. 1 shows the measurement results at 0 °, 400 °, and 800 °.
It is shown in FIG. Solid line a in the figure₁The symbol ● indicates both perpendicular magnetization films 3₁
And 3_TwoAnd the magnetization of
Parallel state, solid line b₁○ shown by is the lower vertical
Magnetic film, in this case second perpendicular magnetic film 3_TwoOnly the magnetization of
The anti-flat that is facing in the opposite direction, that is, facing downward
Indicates the line status. In this case, the first perpendicular magnetization film 3₁Film thickness
Is more than 600 °, it is located opposite to the reading side
In this case, the second perpendicular magnetization film 3_TwoThe magnetization state of
That the modulation of the current signal cannot be obtained sufficiently
You. Therefore, in this case, the film 3 close to the substrate 1₁Film thickness is 600
わ か る It is understood that it is desirable to set the following.

Next, taking the configuration described in FIG. 7, consisting of the in-plane magnetization film of Fe _0.7 Co _0.3 in place of the dielectric film between the first and second vertical magnetic film 3 ₁ and 3 ₂ The cutting layer 4 is provided with a thickness of 40 °, and the first perpendicular magnetization film 3 is formed.
_When the film thickness of ₁ was changed from 100 to 1000 °,
The change of the second signal strength of the perpendicular magnetic film 3 ₂ were measured. The result is shown in FIG. The solid line b ₂ shown by the solid line a ₂ and ○ shows in FIG ●, similar to FIG. 11 described above, a case where each of the perpendicular magnetic film 3 ₁ and 3 ₂ of the magnetization directions respectively becomes parallel, antiparallel Show.

[0057] From this result, the first vertical magnetic film 3 ₁ of the film thickness to be at least 700Å and read side opposite the recording layer or second magnetization state of the vertical magnetization film 3 ₂ When such a configuration It can be understood that the modulation degree of the signal at the time of changing is not sufficiently obtained. Therefore, the first vertical magnetic film 3 ₁ of the film thickness is found to be less desirable 700 Å.

Next, taking the configuration described in FIG. 9, without particularly providing the film as a cutting layer 4 between the first and second vertical magnetic film 3 ₁ and 3 _2, the first vertical magnetic film 3 ₁ after depositing and then 100sec left in the vacuum chamber, the second vertical magnetic film 3 ₂ thereon, a second dielectric film 2 _2, in case where the heat conducting film 5, the first of measuring a second variation of the signal strength of the perpendicular magnetic film 3 ₂ when the perpendicular magnetization film 3 ₁ of the film thickness was varied from 100 to 1000 Å. The result is shown in FIG. Solid line a ₃ indicated by ● in the figure
And solid b ₃ shown in ○ denotes a case where the same manner as FIG. 11 described above, each magnetization direction of the perpendicular magnetization film 3 ₁ and 3 ₂ has parallel, antiparallel.

[0059] This result, such an arrangement a first of the perpendicular magnetization film 3 ₁ of the film thickness and more 700Å and read side opposite the recording layer i.e. the second when taking perpendicular magnetic film 3 ₂
It can be seen that the degree of modulation of the signal when the magnetization state changes is not sufficient. Therefore, the first vertical magnetic film 3 ₁ of the film thickness is found to be less desirable 700 Å.

Therefore, in the present invention, the thickness of the film close to the substrate 1 is selected to be not less than 100 ° and not more than 600 °.

Next, the first and / or second perpendicular magnetization film 3
Close to ₁ and / or 3 _second configuration providing a thermally conductive film 5 having a high thermal conductivity compared to the first and / or second vertical magnetic film 3 ₁ and / or 3 ₂ thermal conductivity The operation and effect will be described below.

In this example, the magneto-optical recording medium 10 is configured by adopting the configuration described in FIG.
By changing the film thickness was measured recording start power Pth ₁ and Pth ₂ of the perpendicular magnetization film 3 ₁ and 3 _2. The result is shown in FIG. The solid line c shown in the figure ○ a first vertical magnetic film 3 _first recording start power, indicating the solid line d is the second recording start power of the perpendicular magnetization film 3 ₂ indicated by ●.

As can be seen from the results, when the heat conductive film 5 is provided, the recording start power P
the difference of th ₁ and Pth ₂ becomes larger, also play power Pread
If the difference between the first and the recording start power Pth ₁ perpendicular magnetization film 3 ₁ it can be seen that a large. That is, by providing the heat conductive film 5, the power margin at the time of recording / reproducing can be expanded, and this is particularly effective for expanding the margin at the time of recording.

It is needless to say that the present invention is not limited to the configuration described in each of the above-described examples, and that the material and thickness of each film can be variously changed and changed. That is, as described above, the first and second vertical magnetic film 3 ₁ and 3 ₂ may be a reverse configuration, and as the material of the dielectric film 2 ₁ to 2 _3, of SiN _X other example ZnS or the like of various Materials can be used. The position of the heat conductive film 5 is not limited to the rear of the dielectric film 2 ₂ or 2 _3, for example between such a second perpendicular magnetic film 3 ₂ and the dielectric film, it is also possible to provide the other position It is. Further, as the material of the magnetized film, the composition range of each element can be changed as described above,
Any of the known rare earth-transition metal amorphous materials may be used, and it goes without saying that Cr, Ti, Al, or the like may be added as an additional element.

[0065]

As described above, according to the present invention, the first and second transparent substrates 2 having different Curie temperatures are used on the flat transparent substrate 2 having no irregularities such as grooves and pits.
The perpendicular magnetization films 3 ₁ and 3 ₂ are laminated and provided, and a preformatted signal is recorded in advance by utilizing a difference in Curie temperature to form an uneven groove or pit on the substrate. Process can be unnecessary. Therefore, it is possible to use a relatively inexpensive transparent substrate material such as a glass substrate having excellent mechanical strength,
The cost can be reduced, the load on the servo system can be reduced, and the yield can be improved.

[0066] Also by providing a further non-magnetic layer or plane magnetization film as a cutting layer between the perpendicular magnetization film 3 ₁ and 3 _2, it is possible to perform recording and reproduction of information signals with good S / N ratio .

Further, the first and second perpendicular magnetization films 3 ₁
And 3 of _2, 100 Å film thickness close to the transparent substrate 1 film
Or 600Å By configuring as follows, can be a modulation of the magnetization states of the first and second vertical magnetic film 3 ₁ and 3 ₂ of the particular film away from the substrate 1 may suffice.

Further, by providing the heat conductive film 5 having a higher thermal conductivity in proximity to the two perpendicular magnetization films 3 ₁ and / or 3 ₂ , the power margin can be increased and a good S Recording / reproduction can be performed with the / N ratio.

Further, by recording the preformat signal and the information signal in the same device,
Since the tracking servo signal and the address signal can be written without causing eccentricity, the load on the servo system can be reduced, and the servo band for the tracking servo signal and the focus servo signal can be reduced to about 1/2.

Further, when a preformat signal is recorded in advance by using a magneto-optical recording device dedicated to preformat signal recording and recording and reproduction of an information signal are performed by using a normal magneto-optical recording device, the eccentricity becomes 10 μm or less. By using the chucking means, the load on the servo system can be similarly reduced, and the servo band can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a magnetization mode of a data zone.

FIG. 3 is an explanatory diagram of a magnetization mode of a preformat signal zone.

FIG. 4 is an explanatory diagram of a magneto-optical recording method.

FIG. 5 is a schematic diagram of a magneto-optical recording device dedicated to preformat signal recording.

FIG. 6 is an explanatory diagram of an example of a chucking unit.

FIG. 7 is a configuration diagram of another embodiment of the present invention.

FIG. 8 is a diagram showing a change in interface domain wall energy with respect to the thickness of a cutting layer.

FIG. 9 is a configuration diagram of another embodiment of the present invention.

FIG. 10 is a diagram showing a time change of the interface domain wall energy with respect to a leaving time.

FIG. 11 is a diagram showing a change in signal intensity with respect to the thickness of a perpendicular magnetization film.

FIG. 12 is a diagram showing a change in signal intensity with respect to the thickness of a perpendicular magnetization film.

FIG. 13 is a diagram showing a change in signal intensity with respect to the thickness of a perpendicular magnetization film.

FIG. 14 is a diagram showing a change in recording start power with respect to the thickness of a heat conductive film.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 ₁ 1st dielectric film 2 ₂ 2nd dielectric film 2 ₃ 3rd dielectric film 3 ₁ 1st perpendicular magnetization film 3 ₂ 2nd perpendicular magnetization film 4 Cutting layer 5 Thermal conductive film 10 Magneto-optical recording medium

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI G11B 11/105 556 G11B 11/105 556C 581 581Z 21/10 21/10 W 23/00 601 23/00 601A (58) Field (Int.Cl. ⁷ , DB name) G11B 11/105 G11B 23/00 G11B 21/10

Claims (8)

(57) [Claims] At least a first perpendicular magnetization film, a cutting layer, a second perpendicular magnetization film, and a heat conduction film are sequentially formed on a flat transparent substrate, and a nonmagnetic layer or an in-plane magnetization film is used as the cutting layer. The heat conductive film is made of a material having a higher thermal conductivity than the thermal conductivity of the first and second perpendicular magnetic films, and has a Curie temperature of the first and second perpendicular magnetic films. When Tc ₁ and Tc ₂ respectively, Tc ₁ <Tc _2, and recording or erasing on the first perpendicular magnetic film without destroying the tracking servo signal recorded on the second perpendicular magnetic film. A magneto-optical recording medium. 2. The magneto-optical recording according to claim 1, wherein at least the first perpendicular magnetic film, the second perpendicular magnetic film, and the heat conductive film are formed by a vacuum thin film forming method. Medium. Wherein said first and second vertical magnetic film each Pth ₁ and Pth ₂ start recording power, the optimum recording power, respectively Prec ₁ and Prec _2, Pread the reproducing power
Then, after irradiating a laser of power Prec ₂ that satisfies Prec ₂ > Pth ₂ to record a tracking servo signal, a recording satisfying Pth ₂ > Prec ₁ > Pth ₁ > Pread under a recording magnetic field Hrec. magneto-optical recording medium according would like the to claim 1 or 2, characterized in that performing recording and erasing by irradiating a laser erasing power Prec _1. 4. The method according to claim 1, wherein the thickness of the first perpendicular magnetization film is 100
4. The magneto-optical recording medium according to claim 1, wherein the angle is not less than {not less than 600}. 5. A flat transparent substrate, at least a first and a perpendicular magnetization film, and a switching fault of a non-magnetic layer or plane magnetization film, the second having a higher Curie temperature than the first vertical magnetized film Recording or erasing data using a magneto-optical recording medium having a perpendicular magnetic film and a heat conductive film having a higher thermal conductivity than the first and second perpendicular magnetic films. at relatively high laser power than the laser power for performing, compared to the first vertical magnetized film
A preformat signal including a tracking servo signal is previously recorded in the second perpendicular magnetization film having a high Curie temperature, and the laser power for recording or erasing the data is used.
The preformat signal recorded on the second perpendicular magnetization film is
Data can be written on the first perpendicular magnetization film without destruction.
Recording or a magneto-optical recording method, wherein that you erasing. 6. When recording the preformat signal in advance, the magnetooptical recording medium is fixed in a state where it is chucked by a spindle motor, and the spindle motor is rotated by a spindle chucking means in a magnetooptical recording apparatus dedicated to preformat signal recording. The pre-format signal is recorded by mounting, and then the eccentricity is reduced to 0 μm by incorporating the magneto-optical recording medium into the magneto-optical recording device together with the spindle motor.
6. The magneto-optical recording method according to claim 5, wherein the thickness is not less than 10 μm. 7. A light source having a function of recording a preformat signal by a spindle chucking means by fixing a magneto-optical recording medium to a spindle motor in a state where the preformat signal is recorded in advance by a chuck. The eccentricity is set to 0 μm or more by attaching the magnetic recording device and recording the preformat signal.
6. The magneto-optical recording method according to claim 5, wherein the thickness is set to 0 μm or less. 8. When the preformat signal is recorded in advance, a boss made of a metal disk is fixed to a center portion of a magneto-optical recording medium, and the boss is fitted to a spindle motor shaft. 6. The magneto-optical recording system according to claim 5, wherein a chucking means for chucking the recording medium with the spindle motor having an eccentricity of 0 μm or more and 10 μm or less is used.