JPH0469830A - Production of magneto-optical recording medium - Google Patents

Abstract

PURPOSE:To obtain a magneto-optical recording medium having good overwriting characteristics by controlling the Ar gas pressure in a specified range during forming a first magnetic film by sputtering so that the magnetic coupling force between magnetic layers can be controlled. CONSTITUTION:The substrate 1 consists of a polycarbonate resin, epoxy resin, glass or the like. The spacer layer 2 and protective layer 6 consist of silicon nitride, silicon oxide, tantalum oxide, aluminum nitride, aluminum oxide, etc. The first magnetic layer 3 and the third magnetic layer 5 are amorphous alloy thin films comprising a combination of rare earth elements and transition metal elements. During the formation of the first magnetic layer, the Ar pressure is specified to 1.0 X 10<-1> Pa. By using the obtd. medium for overwriting, the error rate is low and no previous information remains.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing an overwritable magneto-optical recording medium using a magnetic multilayer film and an initial auxiliary magnetic field.

[Prior art] In recent years, by using an initial auxiliary magnetic field and a magnetic multilayer film,
Magneto-optical recording methods that enable overwriting of information are attracting attention. (a) As a recording medium, a multilayer magneto-optical recording medium is used, in which the first layer having perpendicular anisotropy serves as a recording/reproducing layer, and the second layer having perpendicular anisotropy serves as a recording auxiliary layer. (b) moving the recording medium; (C) aligning only the magnetization of the recording auxiliary layer either upward or downward before recording by applying an initial auxiliary magnetic field; (d) ) irradiating the recording medium with a laser beam; (e) modulating the intensity of the laser beam in a pulsed manner according to the binarized information to be recorded; (f)
applying a recording magnetic field to the portion of the recording medium irradiated with the laser beam; (C1) either a bit having upward magnetization or a bit having downward magnetization when the intensity of the pulsed laser beam is at a high level; This is an overwritable recording method characterized by forming one bit and forming the other bit when the intensity of the laser beam is at a low level (for example, Japanese Patent Laid-Open No. 1982-1993-1).
(See Publication No. 175948).

The M-H loop of the overwritable bilayer media should be as shown at 21 in FIG. 2 at ambient temperature.

For example, in an anti-parallel type two-layer medium that is energetically stable when the magnetization of the 11i magnetic layer and the magnetization of the second magnetic layer are in opposite directions, the conditions for obtaining the M-H loop as shown in Figure 2 are: , Hc2-σw/2M, t2>0 Hc2' Coercive force M, 2 of the recording auxiliary layer; Saturation magnetization t2 of the recording auxiliary layer: The thickness of the recording auxiliary layer is satisfied, but the exchange coupling force between the two layers is If it is too strong, σ will become too large, and the above equation will no longer be satisfied, and the M-1-(loop will become a loop as shown at 31 in FIG. 3).

In order to obtain the M-1-1 loop as shown in FIG. 2, it is necessary to weaken the exchange coupling force between the recording layer and the recording auxiliary layer. One way to weaken the exchange force is to add GdFe between the two layers.
A method of sandwiching a Co layer is known (in, Aratan
i et, al,, 5PIE Vol, 1078°L25B, 0ptical Data Store
ageMeeting.

1989).

[Problems to be Solved by the Invention] However, when a GdFeCo control layer is sandwiched between two layers in order to adjust the exchange coupling force between the two layers as in the conventional case,
In order to weaken the bonding force between the two layers, it is necessary to make the control layer considerably thicker, and if the control layer is sandwiched too thickly between the two layers, there is a problem that overwrite characteristics deteriorate.

The purpose of the present invention is to provide a suitable exchange coupling force between the recording layer and the recording auxiliary layer by sandwiching a thin exchange coupling force controlling m+ layer between each magnetic layer constituting the magneto-optical recording film. An object of the present invention is to provide a method for manufacturing a magneto-optical recording medium having a weak bonding force.

[Means for Solving the Problems] The present invention provides a first method on a substrate. In a method for manufacturing an overwritable magneto-optical recording medium in which second and third magnetic films are sequentially formed and information is recorded, reproduced, and erased using a laser beam, when the first magnetic film is formed by sputtering. A of
This is a method for manufacturing a magneto-optical recording medium, characterized in that the r gas pressure is set in a range of 1.0×10 −1 to 1.0 Pa.

[Example] Next, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a partial sectional view of a magneto-optical recording medium obtained according to an embodiment of the present invention. The medium configuration is substrate 1/spacer layer 2/first magnetic layer 3/second magnetic layer 4/third magnetic layer 5/protective layer 6.

Here, as the substrate 1, a substrate made of polycarbonate resin, epoxy resin, glass, or the like is used. The substrate may be formed by forming groups with ultraviolet curing resin or the like on glass. As the spacer layer 2 and the protective layer 6, silicon nitride, silicon oxide, tantalum oxide, aluminum nitride, aluminum oxide, etc. can be used.

Further, the first magnetic layer 3 and the third magnetic layer 5 are amorphous alloy thin films made of a combination of rare earth elements and transition metals. In this case, the rare earths include, for example, Tb, Gd
, DV, Nd, , Ho, etc., and the transition metal may be Fe.

A single element or a plurality of elements such as Co and Ni are used.

It is also possible to add a small amount of Tr, Or, MO, etc.

Comparative example (Ar pressure during recording layer creation was 0.2X 10-1
.

065xlO-1 and 0.8xlO-I Pa) First, as a comparative example, polycarbonate (with group) substrate/silicon nitride (800 people)/T, bFeCO alloy (180 people>/NdFeCo alloy (40 people)/Gd
T, b Fe Co alloy (600 people) / silicon nitride (
A medium with a film structure of 0.800 people) was used at an argon gas pressure of 0.2X10-1 during the formation of the TbFeC0 alloy layer.
5x 10-1 and 0.8x10-I Pa. All films were formed by continuous sputtering using an RF magnetron sputtering device.

Table 1 shows the results of NdFeCo when the Ar pressure during film formation was changed.
Table 2 shows the characteristics of a single layer of GdTbFeCo layer when the Ar pressure during film formation was changed, and Table 3 shows the characteristics of a single layer of GdTbFeCo layer when the Ar pressure during film formation was changed to 1.0 Pa
The various properties of the TbFeCo alloy layer were shown when the properties were changed within the range below.

NdFeCo control layer, GdT shown in Tables 1 to 3
When various three-layer media were created by combining the bFeCo recording auxiliary layer and the TbFeC0 recording layer, all of the Kerr loops were as shown in FIG. 3. Tb
This is because the magnetic coupling force between the FeCo alloy layer and the GdTbFeCo alloy layer is too strong. These media could not be overwritten.

(Margin below) Table 1 NdFeC when changing Ar pressure.

Characteristics of control layer Table 2 Characteristics of GdTbFeC0 recording auxiliary layer when changing Ar pressure Table 3 TbFeC at each Ar gas pressure.

Recording layer characteristics Example (1) Ar pressure at the time of recording layer creation was 1.0xlO-I Pa
In this case, the properties of the single TbFeCo layer were as shown in Table 4.

Table 4 (1-1) Ar gas pressure when creating the control layer and recording auxiliary layer is na, ox 10-2 Pa, and 8.0, respectively.
A three-layer film was prepared using the recording layer whose characteristics are shown in Table 4 at X10-2 Pa, the NdFeCo control layer and the GdTbFeCo recording auxiliary layer whose characteristics are shown in Tables 1 and 2. The Kerr loop of this three-layer film was as shown in FIG. At this time, TbFeC.

The reversal field of the layer and the GdTbFeCo layer is 2
They were 5.0 koe and 2.0 kOe.

Next, overwriting was performed on this medium.

First, the linear velocity was 11.3 ms, and the recording frequency was 3.7
MHz.

DuTy ratio 50%, initial auxiliary magnetic field 2.9 kOe, recording magnetic field 4000e, low level laser beam power 4,
OmW, high level laser beam power 13.0
When recorded and played back under mW conditions, C/854d8
was gotten. On top of this, the linear velocity is 11.3 ms.

Recording frequency 7.4 MB2. When overwritten under the conditions of DUTV ratio 50%, initial auxiliary magnetic field 2.9 kOe, recording magnetic field 4000e, low level laser beam power 4.0 mW, and high level laser beam power 13.0 mΔ, the result was 48 dB. A reproduced signal was obtained. The error rate was 10-5 to 10-6. At this time 3
．． The 78H2 signal (previous information) did not appear at all.

(1-2) Ar gas pressure at the time of creating the control a layer and the recording auxiliary layer was 4.0X10-2 Pa and 3.0Xio, respectively.
A three-layer film was prepared using the recording layer whose characteristics are shown in Table 4 at -+pa, the NdFeCo control layer and the GdTbFeCo recording auxiliary layer whose characteristics are shown in Tables 1 and 2. The Kerr loop of this three-layer film was as shown in FIG. At this time, TbFeC.

The reversal field of the layer and the GdTbFeCo layer is 2
They were 5.0 kOe and 2.4 kOe.

Next, overwriting was performed on this medium.

First, the linear velocity was 11.3 ms, and the recording frequency was 3.7
MHz.

DuTy ratio 50%, initial auxiliary magnetic field 4.0 koe, recording magnetic field 3000e, low level laser beam power 4.
0 mW, high level laser beam power 13, Om
When recorded and played back under W conditions, C/N was 53 dB.
was gotten. On top of this, the linear velocity is 11.3 ms.

Under the conditions of recording frequency 7.48H2, DuTy ratio 50%, initial auxiliary magnetic field 4.0 kOe, recording magnetic field 3500e, low level laser beam power 4.0111W, and high level laser beam power 13.0+nW. When overwritten, a reproduced signal of 48 dB was obtained. The error rate was 10-5 to 10-6. At this time, the 3.7) IHz signal (previous information) did not appear at all.

(1-3) Ar gas pressure at the time of creating the control layer and recording auxiliary layer was 6.0x10-I Pa and 6.0x10-I Pa, respectively.
-I Pa A three-layer film was prepared using the recording layer whose characteristics are shown in Table 4, the NdFeCo control layer and the GdTbFeCo recording auxiliary layer whose characteristics are shown in Tables 1 and 2. The Kerr loop of this three-layer film was as shown in FIG. At this time, TbFeC.

The reversal field of the layer and the GdTbFeCo layer is 2
There were 5.0 kOe and 3.0 kOer.

Next, overwriting was performed on this medium.

First, the linear velocity was 11.3 mis, and the recording frequency was 3.78.
H2゜DuTy ratio 50%, initial auxiliary magnetic field 4.0 kOe
, recording magnetic field 3500e, low level laser beam power 4.0 mW, high level laser beam power 1
3. When recorded and played back under OmW conditions, C/N5
3 (1B was obtained. On top of this, the linear velocity moon, 3 mi
s.

Recording frequency 7.4 MHz, DuTy ratio 50%
, initial auxiliary magnetic field 4.0 kOe, recording magnetic field 3500e
, low level laser beam power 4.0 mW, high level laser beam power 13. When overwritten under OmW conditions, a reproduced signal of 48 dB was obtained. The error rate was 10-5 to 10-6. At this time, the 3.7 MHz signal @ (previous information) did not appear at all.

(2) Ar pressure during recording layer creation was 3.0X10-I Pa
In this case, the characteristics of the single TbFeCo layer were as shown in Table 5.

Table 5 (2-1) Ar gas pressure at the time of creating the control layer and recording auxiliary layer was 4, OX 10-2 Pa, and 8.0x1, respectively.
At 0-2 Pa, the recording layer whose characteristics are shown in Table 5, the NdFeCo control layer I layer and the GdTbFeC0 whose characteristics are shown in Tables 1 and 2.
A three-layer film was created using the recording auxiliary layer. The Kerr loop of this three-layer film was as shown in FIG. At this time, TbFeC.

The reversal field of the layer and the GdTbFeC0 layer is 2
They were 6.0 kOe and 2.2 kOe.

Next, overwriting was performed on this medium.

First, linear velocity 11.3 m/s, recording frequency 3.7
MHz.

DLJTV ratio 50%, initial auxiliary magnetic field 2.9 kOe, recording magnetic field 3500e, low level laser beam power 4
, OmW, high level laser beam power 13.0
When recorded and played back under mW conditions, C/854
dB was obtained. On top of this, a linear velocity of 11; 3 m/s
.

Recording frequency 7.4 HN3. D u T ¥ ratio 50%
, initial auxiliary magnetic field 2.9 kOe, recording magnetic field 3000e
When overwriting was performed under the conditions of a low level laser beam power of 4.0 mW and a high level laser beam power of 13.0 mW, a reproduced signal of 47 dB was obtained. The incidence of gills was 5 to 6 per leaf. At this time 3
．． The 7MHz signal (previous information) did not appear at all.

(2-2) Ar gas pressure at the time of creating the control layer and recording auxiliary layer was 6.0xlO-I Pa and 8.0x10, respectively.
-2 Pa A three-layer film was prepared using a recording layer whose properties are shown in Table 5, an NdFeCo control layer and a GdTbFeCo recording auxiliary layer whose properties are shown in Tables 1 and 2. The Kerr loop of this three-layer film was as shown in FIG. At this time, the reversal magnetic fields of the TbFeC0 layer and the GdTbFeCo layer are 25.0 kOe and 2.3 kOe, respectively.
Met.

Next, overwriting was performed on this medium.

First, linear velocity 11.3 m/s, recording frequency 3.7
MHz.

DuTy ratio 50%, initial auxiliary magnetic field 2.9 kOe, recording magnetic field 3500e, low level laser beam power 4,
OmW, high level laser beam power 13.0m
When recorded and played back under - conditions, C/854 dB
was gotten. On top of this, the linear velocity is 11.3 m/s.

Under the conditions of recording frequency 7.48H2, DuTy ratio 50%, initial auxiliary magnetic field 2.9 kOe, recording magnetic field 3500e, low-level laser beam power 4, OmW, and high-level laser beam power 13.0mW. When overwritten, a reproduced signal of 48 dB was obtained. The error rate was 10-5 to 10-6. At this time 3
．． The 7MHz signal (previous information) did not appear at all.

(2-3) Ar gas pressure at the time of creating the control layer and the recording auxiliary layer was 3.0xlO-I Pa and 3.0x10
-I Pa A three-layer film was prepared using the recording layer whose characteristics are shown in Table 5, the NdFeC0 control layer and the GdTbFeCo recording auxiliary layer whose characteristics are shown in Tables 1 and 2. The Kerr loop of this three-layer film was as shown in FIG. At this time, TbFeC.

The reversal field of the layer and the GdTbFeCo layer is 2
They were 6.0 kOe and 3.0 kOe.

Next, overwriting was performed on this medium.

First, the linear velocity was 11.3 m/s, the recording frequency was 3.7 to 2°, the DuTy ratio was 50%, the initial auxiliary magnetic field was 4.0 kOe,
Recording magnetic field 350. Oe, low level laser beam power 4, OmW, high level laser beam power 1
When recorded and played back under 3.0 mW conditions, C/8
53 dB was obtained. On top of this, a linear velocity of 11.3 m
/s.

Under the conditions of recording frequency 7.48H2, Du TV ratio 50%, initial auxiliary magnetic field 2.9 kOe, recording magnetic field 3500e, low level laser beam power 4゜OmW, and high level laser beam power 13.0111H. When overwritten, a reproduced signal of 47 dB was obtained. The error rate was 10-5 to 10-6. At this time, the 3.7 MHz signal @ (previous information) did not appear at all.

(3) Ar pressure at the time of recording layer creation was 5.0X10-I Pa
The properties of the single TbFeCo layer were as shown in Table 6.

Table 6 (3-1) Ar gas pressure at the time of creating the control layer and the recording auxiliary layer was 4. Ox 10-2 Pa and 4. OX
A three-layer film was prepared using a recording layer whose properties are shown in Table 6 at 10-2 Pa, an NdFeCo control layer and a GdTbFeCo recording auxiliary layer whose properties are shown in Tables 1 and 2. The Kerr loop of this three-layer film was as shown in FIG. At this time, TbFeC.

The reversal field of the layer and the GdTbFeCo layer is 2
They were 6.0 kOe and 2.2 kOe.

Next, overwriting was performed on this medium.

First, linear velocity 11.3 m/s, recording frequency 3.78
H2゜DuTy ratio 50%, initial auxiliary magnetic field 4. , Okoe
, recording layer PiL3500e, low-level laser beam power 4, Oin, and high-level laser beam power 12.0 mW. When recording and reproducing, C/
N53dB was obtained. On top of this, a linear velocity of 11.3 m
is.

Recording frequency 7.4) IHz, DuTy ratio 50
%, initial auxiliary magnetic field 4.0 kOe, recording magnetic field 3000e
, low level laser beam power 4.0 mW,
When overwriting was performed under the condition of a high level laser beam power of 12.0 m-, a reproduced signal of 47 dB was obtained. The error rate was 10-5 to 10-6. At this time, the 3.78H2 signal (previous information) did not appear at all.

(3-2) Ar gas pressure at the time of creating the control layer and recording auxiliary layer was 1.5xlO-I Pa and 1.5x10
A three-layer film was prepared using the recording layer whose characteristics are shown in Table 6 at -f Pa, the NdFeCo control layer and the GdTbFeCo recording auxiliary layer whose characteristics are shown in Tables 1 and 2. The Kerr loop of this three-layer film was as shown in FIG. At this time, the reversal magnetic fields of the TbFeC0 layer and the GdTbFeCo layer were 26, OkOe, and 2.4 kOe, respectively.

Next, overwriting was performed on this medium.

First, the linear velocity was 11.3 ms, and the recording frequency was 3.7
MHz.

DuT'i/ratio 50%, initial auxiliary magnetic field 4°Okoe, recording magnetic field 3500e, low level laser beam power 4
, OmW , High level Shi~The Beam power 12.0
When recorded and played back under mW conditions, the C/N was 53.
dB was obtained. On top of this, the linear velocity is 11.3 ms
.

Recording frequency 7.48H2, Du TV ratio 50%, initial auxiliary magnetic field 2.9 kOe, recording magnetic field 3000e, low level laser beam power 4.0 mW, high level laser beam power 13.0 m- When overwritten under these conditions, a reproduced signal of 47 dB was obtained. The error rate was 10-5 to 10-6. At this time 3
, 7) The fHz signal (previous information) did not appear at all.

(3-3) When the Ar gas pressure at the time of creating the control layer and recording auxiliary layer was 3.0xlO-I Pa and 3.0xlO-IPa, respectively, the recording layer whose characteristics are shown in Table 6, Table 1 , NdFeCo!, whose characteristics are shown in Table 2. IJwJ layer and (3dTbFe
A three-layer film was created using a Co recording auxiliary layer. The Kerr loop of this three-layer film was as shown in FIG.

At this time, TbFeC.

The reversal field of the layer and the GdTbFeCo layer is 2
They were 6.0 koe and 2.7 kOe.

Next, overwriting was performed on this medium.

First, the linear velocity was 11.3 ms and the recording frequency was 3.7 Z.

DuTy ratio 50%, initial auxiliary magnetic field 4.0 kOe, recording magnetic field 3500e, low level laser beam power 4,
Oml+l, high level laser beam power 12.
When recorded and played back under 0 mW conditions, C/852
dB was obtained. On top of this, the linear velocity is 11.3111/
S.

Recording frequency 7.4 MHz, DuTy ratio 50%, initial auxiliary magnetic field 4.0 koe, recording magnetic field 3000e, low level laser beam power 4.0 mW, high level laser beam power 12.0 mW. When overwritten, a reproduced signal of 46 dB was obtained.

The gill incidence was 10-5 to 6 per leaf. At this time 3,
The 7Hz signal (previous information) did not appear at all.

(4) Ar pressure during recording layer creation was 8.0xlO-IP
In the case of a, the characteristics of the single TbFeCo layer were as shown in Table 7.

Table 7 (4-1) Ar gas pressure at the time of creating the control layer and recording auxiliary layer was 4. Ox 10-2 Pa and 1.5X
A three-layer film was prepared using the recording layer whose properties are shown in Table 7 at 10-1 Pa, the NdFeC◯ control layer and the GdTbFeCo recording auxiliary layer whose properties are shown in Tables 1 and 2. The Kerr loop of this three-layer film was as shown in FIG. At this time, TbFeC.

The reversal field of the layer and the GdTbFeC0 layer is 2
They were 8.0 kOe and 2.4 kOe.

Next, overwriting was performed on this medium.

First, linear velocity 11. ．． 3 m/s, recording frequency 3.7
MHz.

DuTy ratio 50%, initial auxiliary magnetic field 4.0 kOe, recording magnetic field 3000e, low level laser beam power 4,
, OmW, high level laser beam power 11.0
When recorded and played back under mW conditions, C/852
dB was obtained. On top of this, the linear velocity is 11.3 m/s
.

Recording frequency 7.4 MIIZ, D LJ TV ratio 5
0%, initial auxiliary magnetic field 4.0 koe, recording magnetic field 3000
e, low-level laser beam power 4.0 mW
When overwriting was performed under the condition of a high-level laser beam power of 11.0 mW, a reproduced signal of 46 dB was obtained. The error rate was 10-5 to 10-6.

At this time, the 3.7 Hz signal (previous information) did not appear at all.

(4-2) Ar gas pressure at the time of creating the control layer and the recording auxiliary layer was e, oxio-t pa, and 4.0×10, respectively.
-2 Pa, the recording layer whose characteristics are shown in Table 7, the NdFeCo1VilI layer and GdTbFe whose characteristics are shown in Tables 1 and 2.
A three-layer film was created using a Co recording auxiliary layer. The Kerr loop of this three-layer film was as shown in FIG.

At this time, TbFeC.

The reversal field of the layer and the GdTbFeCo layer is 2
They were 8.0 koe and 2.4 kOe.

Next, overwriting was performed on this medium.

First, linear velocity 11.3 m/s, recording frequency 3.78
H2゜DuTy ratio 50%, initial auxiliary magnetic field 4.0 kOe
, recording magnetic field 3000e, low level laser beam power 4, OtW, high level laser beam power 11,
When recorded and played back under OmW conditions, C/853
dB was obtained. On top of this, a linear velocity of 11.3 m/s
.

Conditions: recording frequency 7.4 MHz, [)uTy ratio 50%, initial auxiliary magnetic field 4.0 koe, recording magnetic field 3000e, low level laser beam power 4.0 mW, high level laser beam power 11.0 mW. When overwritten with , a reproduced signal of 46d8 was obtained. The error rate was 5 to 10-6 per leaf. At this time 3.
1) The tHz belief @ (previous information) did not appear at all.

(4-3) Ar gas pressure at the time of creating the control layer and the recording auxiliary layer was 6.0×10-Pa and 3.0×10-Pa, respectively.
f Pa, the recording layer whose characteristics are shown in Table 7, the NdFe'COIIJm layer and GdTbFeC whose characteristics are shown in Tables 1 and 2.
o A three-layer film was created using the recording auxiliary layer. The Kerr loop of this three-layer film was as shown in FIG. At this time, TbFeC.

The reversal field of the layer and the GdTbFeCo layer is 2
They were 8.0 kOe and 2.7 kOe.

Next, overwriting was performed on this medium.

First, linear velocity 11.3 m/s, recording frequency 3.7
Mn2゜DuTy ratio 50%, initial auxiliary magnetic field 4.0 kO
e, recording magnetic field 3000e, low level laser beam power 4, OmW, high level laser beam power 1
When recorded and played back under the condition of 1゜OmH, the C/N was 5.
1 dB was obtained. On top of this, the linear velocity is 11.311/
S.

Recording frequency 7.4 MH7, Du TV ratio 50%,
Initial auxiliary magnetic field 4.0 kOe, recording magnetic field 3000e,
When overwriting was performed under the conditions of a low level laser beam power of 4.0111 W and a high level laser beam power of 11.0 mW, a reproduced signal of 46 dB was obtained. The error rate was 10-5 to 10-6. At this time, the 3.78H2 signal (previous information) did not appear at all.

(5) TbF when the Ar pressure during recording layer creation is 1.0 Pa
The properties of the single eC0 layer were as shown in Table 8.

Table 8 (5-1) The Ar gas pressure at the time of creating the control layer and the recording auxiliary layer was 3. Ox 10-1 Pa and 4, OX
A three-layer film was prepared using a recording layer whose properties are shown in Table 8 at 10-2 Pa, an NdFeCo control layer and a GdTbFeCo recording auxiliary layer whose properties are shown in Tables 1 and 2. The Kerr loop of this three-layer film was as shown in FIG. At this time, TbFeC.

The reversal field of the layer and the GdTbFeCo layer is 2
They were 8.0 kOe and 2.5 koe.

Next, overwriting was performed on this medium.

First, linear velocity 11.3 m/s, recording frequency 3.7
) IHz.

DuTytL5o%, initial auxiliary magnetic field 4.0 koe, recording magnetic field 2C)OOe, low level laser beam power 4.0111W, high level laser beam power 9
．． When recorded and played back under 0mW conditions, C/N 5
0 dB was obtained. On top of this, a linear velocity of 11.3 m/s
, recording frequency 7.4.8H2, DLJ TV ratio 5
0%, initial auxiliary magnetic field 4.0 koe, recording magnetic field 2000
e, low level laser beam power 4.0 mW
When overwriting was performed under the condition of a high-level laser beam power of 9.0IIIW, a reproduced signal of 45d8 was obtained. The gill incidence was 5 to 10-6 per leaf. At this time, the 3.78H2 signal (previous information) did not appear at all.

(5-2) Ar gas pressure at the time of creating the control layer and recording auxiliary layer was 3.0x10-I Pa and 1.5x10-I Pa, respectively.
A three-layer film was prepared using the recording layer whose characteristics are shown in Table 8 at -2 Pa, the NdFeCo control layer and the GdTbFeCo recording auxiliary layer whose characteristics are shown in Tables 1 and 2. The Kerr loop of this three-layer film was as shown in FIG. At this time, the reversal magnetic fields of the TbFeC0 layer and the GdTbFeCo layer are 28.0 koe and 2.7 koe, respectively.
Met.

Next, overwriting was performed on this medium.

First, linear velocity 11.3 m/s, recording frequency 3.7
MHz.

DuTy ratio 50%, initial auxiliary magnetic field 4.0 kOe, recording magnetic field 2000e, low level laser beam power 4,
OmW, high level laser beam power 9.0Il
When recorded and played back under the conditions of lIl, the C/N was 51.
dB was obtained. On top of this, the linear velocity is 11.3111/S
, recording frequency 7.4 MHz, DuTV ratio 5
0%, initial auxiliary magnetic field 4.0 kOe, recording magnetic field 2000
e, low-level laser beam power 4.0 mW
When overwriting was performed under the condition of a high-level laser beam power of 9.0 mW, a reproduced signal of 45 dB was obtained. The gill incidence was 10-5 to 10-6. At this time, 3.7) IH7 signal (previous information) did not appear at all.

(5-3) The Ar gas pressure during the creation of the control layer and recording auxiliary layer was 6. ()xlO-I Pa and 6.0×1
A three-layer film was prepared using the recording layer whose characteristics are shown in Table 8 at 0-f Pa, the NdFeC0 control layer and the GdTbFeCo recording auxiliary layer whose characteristics are shown in Tables 1 and 2. The Kerr loop of this three-layer film was as shown in FIG. At this time, TbFeC.

The reversal field of the layer and the GdTbFeCo layer is 2
9.0 kOe and 3.0 kOe.

Next, overwriting was performed on this medium.

First, linear velocity 11.3 m/s, recording frequency 3.78
H7゜DuTy ratio 50%, initial auxiliary magnetic field 4.0 kOe
, recording magnetic field 2000e, low-level laser beam power 4.0 mW, and high-level laser beam power 9.0 mW.
50dB was obtained. On top of this, the linear velocity is 11.3 m/
s, recording frequency 7.4 MH2, Du TV ratio 5
0%, initial auxiliary magnetic field 4.0 kOe, recording magnetic field 2000
e, low-level laser beam power 4.0 mW,
When overwriting was performed under the condition of a high-level laser beam power of 9.0 mW, a reproduction signal of 45 dB was generated by 1q. The error rate was 10-5 to 10-6. At this time, the 3.7MH2 signal (previous information) did not appear at all.

[Effects of the Invention] As explained above, according to the method of the present invention, it is possible to adjust the magnetic coupling force between magnetic layers, and as a result,
A magneto-optical recording medium with good overwrite characteristics can be obtained.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view of an example of a magneto-optical recording medium obtained by the method of the present invention, and FIG. 2 is a characteristic diagram showing the M-H loop of an example of the magneto-optical recording medium obtained by the method of the present invention. , FIG. 3 is a characteristic diagram showing the M-1-1 loop of the magneto-optical recording medium when the method of the present invention is not applied.

Claims (1)

[Claims] (1) In a method for manufacturing an overwritable magneto-optical recording medium in which first, second and third magnetic films are sequentially formed on a substrate and information is recorded, reproduced and erased using a laser beam, 1. A method for producing a magneto-optical recording medium, characterized in that the Ar gas pressure when forming the magnetic film of No. 1 by sputtering is in the range of 1.0×10^-^1 to 1.0 Pa.