JPH06119666A - Magneto-optical recording medium - Google Patents

Abstract

PURPOSE:To decrease the crosstalks from proximity tracks and to lessen noise generation by the information remaining without being erased by reading the stored information only out of the part of a reproducing light spot below the Curie temp. of a transfer magnetic film. CONSTITUTION:The Curie temps. and coercive forces of the reproducing magnetic film 66, the transfer magnetic film 67 and the recording magnetic film 68, designated as Tc1, Tc2, Tc3 and Hc1, Hc2, Hc3, are set at Tc2<Tc1, Tc2<Tc3 and Hc1<Hc2 from room temp. to Tc2. A region 65 above the temp. Tc2 of the magnetic film 67 annihilates magnetization by irradiation with reproducing light 63 at the time of reproduction and therefore, the exchange bond between the magnetic films 66 and 68 corresponding to the part is shut off and the magnetization of the magnetic film 66 is in the direction of the magnetic field 61 for reproduction. The recorded information is then read only out of the part of the temp. Tc2 or below in the part of the reproducing light spot 64 and the recording magnetic domain smaller than the spot 64 is reproduced without the waveform interference from the previous recording magnetic domain and further, there is no recording magnetic domain in the inter-recording track part 66a of the magnetic film 66, and therefore, the crosstalks from the proximity tracks are decreased.

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 recording and erasing are performed by utilizing a temperature rise due to a laser beam, and reproduction is performed by utilizing a magneto-optical effect, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Recording on a magneto-optical recording medium is carried out by locally irradiating a recording film by irradiation with a laser beam to a temperature having a small coercive force higher than a compensation temperature or a Curie temperature and irradiating an external magnetic field on the recording film. It is performed by magnetizing in the direction of (1) to form a recording magnetic domain (thermomagnetic recording). Further, in reproducing the recording signal, the polarization plane of the reflected light or the transmitted light is rotated according to the recording state (magnetization direction of the recording magnetic domain) of the recording film by irradiation with laser light having a power lower than the laser power at the time of recording / erasing. (Magneto-optical effect) It is performed by detecting the situation.

In the conventional recording method, a laser beam of a constant intensity is irradiated to raise the temperature of the recording film, and thermomagnetic recording is performed by an external magnetic field whose direction is modulated according to a recording signal (magnetic field modulation). (Recording method) and a method of irradiating a laser beam whose intensity is modulated according to a recording signal under an external magnetic field of constant intensity to locally raise the temperature of the recording film and perform thermomagnetic recording (optical modulation recording method). ).

In the conventional general magneto-optical recording medium, when the recording magnetic domain becomes smaller than the reproducing light spot diameter, the recording magnetic domains before and after the recording magnetic domain to be reproduced are also included in the detection range of the reproducing light, and interference from them occurs. Therefore, there is a problem in that the reproduction signal becomes small and the S / N decreases.

Further, if the distance between the recording tracks is made smaller than the reproducing light spot diameter, crosstalk from the adjacent tracks increases and reproduction jitter occurs, which hinders improvement of the track recording density.

Therefore, a magneto-optical recording medium having the structure shown in FIG. 7 has been proposed. In FIG. 7, (a) is a top view and (b) is a side sectional view.

Reference numeral 71 is a recording / reproducing magnetic field, 72 is a reproducing light, 73 is a reproducing light spot, 74 is a recording magnetic domain, 75 is a region having a temperature of Tc or higher, 76 is a reproducing magnetic film made of a magnetic film having a low coercive force, and 77. Is a transfer magnetic film made of a magnetic film having a low Curie temperature, 78 is a recording magnetic film made of a magnetic film having a high coercive force, and the reproducing magnetic film 76, the transfer magnetic film 77 and the recording magnetic film 78 are exchange-coupled. The recording layer is composed of three layers. Information is thermomagnetically recorded on the recording magnetic film 78 as recording magnetic domains 74 under the recording magnetic field 71. The recording magnetic domains 74 of the recording magnetic film 78 are transferred to the reproducing magnetic film 76 via the transfer magnetic film 77, The magnetization of the reproducing magnetic film 76 is aligned with the magnetization direction of the recording magnetic film 78. During reproduction, the temperature of a portion 75 of the transfer magnetic film 77 rises above the Curie temperature Tc due to reproduction light irradiation and the magnetization disappears. Therefore, the reproduction magnetic film 76 and the recording magnetic film 7 corresponding to that portion.
The exchange coupling between the two is cut off, and the magnetization of the reproducing magnetic film 76 corresponding to that portion is aligned in the direction of the reproducing magnetic field 71.

Therefore, the temperature Tc of the reproducing light spot is
The stored information can be read out as a reproduction signal only from the following portions. As a result, a recording magnetic domain smaller than the size of the reproducing light spot can be reproduced without waveform interference from the previous recording magnetic domain.

[0009]

However, in the conventional magneto-optical recording medium as described above, although the linear recording density in the length direction of the recording track can be improved, as shown in FIG. Of which, Tc, which is the information reproducible area
Since the range of the following part does not become too narrow in the width direction of the recording track, if the recording track interval is made smaller than the reproducing light spot diameter, and if the recording condition exceeds the recording track, the adjacent track will be recorded. However, there is a problem that the crosstalk from the disk increases and the track recording density cannot be improved.

Further, when thermomagnetic recording is performed, the higher the recording laser power is, the larger the recording magnetic domain is in the width direction of the recording track. Therefore, when recording is performed with a high laser power and erased with a low laser power, the end of the recording track is increased. There is a problem in that a recording magnetic domain in a portion or a portion protruding from a recording track is left unerased, which causes noise.

In view of the above-mentioned problems, the present invention reduces the waveform interference in the recording magnetic domain and the crosstalk from the adjacent tracks to improve the recording density, and causes the recording domain to remain unerased even when the recording / erasing power fluctuates. The present invention provides a high-performance magneto-optical recording medium with less noise generation and a method for manufacturing the same.

[0012]

In order to solve the above problems, a magneto-optical recording medium of the present invention is a recording comprising a reproducing magnetic film, a transfer magnetic film and a recording magnetic film magnetically coupled to a substrate. A recording signal is recorded on the recording magnetic film as a magnetic domain, the transfer magnetic film transfers the recording magnetic domain of the recording magnetic film to the reproducing magnetic film, and the recording magnetic domain transferred to the reproducing magnetic film. Is reproduced as a reproduction signal by being converted into an optical signal by the magneto-optical effect, and the Curie temperature and coercive force of the reproducing magnetic film, the transfer magnetic film, and the recording magnetic film are Tc1, Tc2, and Tc2, respectively.
When Tc3 and Hc1, Hc2, Hc3 are set, Tc2 <
Tc1, Tc2 <Tc3 and Hc1 <Hc3 from room temperature to near Tc2 are set, and between the recording tracks of at least one of the reproducing magnetic film, the transfer magnetic film and the recording magnetic film. The method for producing a magneto-optical recording medium of the present invention comprises a reproducing magnetic film, a transfer magnetic film and a recording magnetic film magnetically coupled on a substrate. At least one of the magnetic films is recorded by irradiating a magneto-optical recording medium having a recording layer made of a film with laser light and heat-treating only a portion of the recording layer located between recording tracks. It is provided with a structure that deteriorates the magnetic characteristics of the portion located between the tracks.

[0013]

The operation of the magneto-optical recording medium of the present invention will be described with reference to FIG. FIG. 6 is a schematic diagram of the magneto-optical recording medium of the present invention. This is a structure in which the magnetic characteristics of the portion of the conventional magneto-optical recording medium shown in FIG. 7 located between the recording tracks of the recording magnetic film are deteriorated. Has become. In FIG. 6, 61 is a recording / reproducing magnetic field, 62 is an initialization magnetic field, and 6
3 is reproduction light, 64 is reproduction light spot, and 65 is temperature Tc2
The above area, 66 is a reproducing magnetic film having a coercive force Hc1, 67 is a transfer magnetic film having a Curie temperature Tc2, and 68 is a coercive force H.
The recording magnetic film c3 and 69 are recording magnetic domains, and the magnetic characteristics of the portion 68a of the recording magnetic film 68 located between the recording tracks are deteriorated. This portion is different from the corresponding portion 67a of the transfer magnetic film 67. Magnetic coupling is small.

Here, information is thermomagnetically recorded as the recording magnetic domains 69 of the recording magnetic film 68 under the recording magnetic field 61, but the recording magnetic domains 69 of the recording magnetic film 68 are reproduced magnetically via the transfer magnetic film 67. The magnetization of the reproducing magnetic film 66 transferred to the film 66 is aligned with the magnetization direction of the recording magnetic film 68. However, since the magnetic characteristics of the portion 68a located between the recording tracks of the recording magnetic film 68 are deteriorated, the recording condition is such that a recording magnetic domain is formed by protruding the recording track of the recording magnetic film 68 during recording. However, the same magnetic domain as the recording magnetic domain is not formed in this portion 68a.
The portions 66a and 67a located between the recording tracks of the reproducing magnetic film 66 and the transfer magnetic film 67 having a small magnetic coupling with a.
Magnetization is aligned with the direction of the initializing magnetic field 62.

During reproduction, the temperature of a portion 65 of the transfer magnetic film 67 rises above its Curie temperature Tc2 due to irradiation of reproducing light, and the magnetization disappears. Therefore, between the reproducing magnetic film 66 and the recording magnetic film 68 corresponding to that portion. Exchange coupling is blocked, and the magnetization of the reproducing magnetic film 66 corresponding to that portion is aligned in the direction of the reproducing magnetic field 61.

Therefore, the temperature Tc of the reproducing light spot is
The stored information can be read out as the reproduction signal only from the portion of 2 or less, and the recording magnetic domain smaller than the size of the reproducing light spot can be reproduced without the waveform interference from the previous recording magnetic domain. Further, since the recording magnetic domain does not exist in the portion 66a of the reproducing magnetic film 66 located between the recording tracks regardless of the magnitude of the recording laser power, the crosstalk from the adjacent tracks is reduced and the fluctuation of the recording / erasing power is suppressed. However, noise generation due to the unerased portion of the recording magnetic domain is also reduced.

In the above description, the case where the magnetic characteristics of the portion 68a of the recording magnetic film 68 located between the recording tracks is deteriorated has been described.
6 or the magnetic properties of the portion 66a or 67a located between the recording tracks of the transfer magnetic film 67 are deteriorated, the same operation can be obtained with the same flow. Of course, the same is true when the magnetic characteristics of the portions of the magnetic films located between the recording tracks of two or all of the magnetic films are deteriorated. Here, the portion 6 located between the recording tracks of the reproducing magnetic film 66.
When the magnetic characteristics of 6a are deteriorated, since the reproduction output by the magneto-optical effect from the portion 66a located between the recording tracks is very small, the initialization magnetic field 62 becomes unnecessary.

When reproducing using the polar Kerr effect, each magnetic film is preferably a perpendicular magnetization film, and when reproducing using a magneto-optical effect other than the polar Kerr effect, each magnetic film is used. May be an in-plane magnetized film.

Next, according to the method for producing the magneto-optical recording medium of the present invention, the magneto-optical recording medium of the present invention is produced as follows with the above configuration. That is, a reproducing magnetic film, a transfer magnetic film, and a recording magnetic film, which are magnetically coupled, are formed as a recording layer on the substrate. In this state, the crosstalk from the adjacent tracks when the recording track interval is shortened. It is not possible to suppress the generation of noise due to the unerased portion of the recording magnetic domain with respect to the increase of the recording power and the fluctuation of the recording / erasing power. Therefore, by irradiating only the portion of the recording layer located between the recording tracks with the laser light after the film formation to perform heat treatment, at least one of the magnetic films constituting the recording layer is magnetically affected only in that portion. The characteristics are deteriorated, and the large magneto-optical effect, magnetization, perpendicular magnetic anisotropy, etc. inherent in the magnetic film are lost. Here, the laser light irradiation is performed with an intensity of several times the recording laser power,
Since it is a method of irradiating a minute area of a magneto-optical recording medium having a dielectric protective film between the substrate and the recording layer in an extremely short time,
Even if the temperature of the recording film rises by several hundreds, the recording film can be heat-treated without damaging the plastic substrate.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A magneto-optical recording medium according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the structure of the magneto-optical recording medium in this embodiment. In FIG. 1, 10 is a recording and reproducing magnetic field, 11 is reproducing light, 12 is a substrate made of polycarbonate, and 13 and 1
7 is a protective layer made of a SiN film, 14 is a Curie temperature Tc
1, a reproducing magnetic film made of a GdFeCo film having a coercive force Hc1, 15 a Curie temperature Tc2, a transfer magnetic film made of a TbFe film having a coercive force Hc2, 16 a Curie temperature T
c3, a recording magnetic film made of a TbFeCo film having a coercive force Hc3, 18 is a recording magnetic domain, and the reproducing magnetic film 14, the transfer magnetic film 15 and the recording magnetic film 16 are perpendicularly magnetized films and are magnetically coupled. The recording layer 19 is composed of the magnetic film. Here, each film on the substrate 12 is formed by a sputtering method or a vacuum evaporation method, and each film has a thickness of the protective layer 13.
And 17 were set to 80 nm, the reproducing magnetic film 14 was set to 40 nm, the transfer magnetic film 15 was set to 10 nm, and the recording magnetic film 16 was set to 50 nm. The Curie temperature is Tc1 300 ° C, Tc1
2 was 120 ° C., Tc3 was 230 ° C., and coercive force was set to Hc1 of around 100 Oersted, Hc2 of around 3 kilo Oersted, and Hc3 of around 15 kilo Oersted at room temperature.

FIG. 3 shows an outline of an apparatus for producing a magneto-optical recording medium having the above structure. Reference numeral 31 is a magneto-optical recording medium in which the above layers have been formed on the substrate (for convenience, the layers other than the recording layer are not shown), 32 is the substrate, and 33 is a portion located between the recording tracks of the recording layer. , 33a is a heat-treated portion between recording tracks, 34 is a portion used as a recording track of a recording layer, 35 is a laser beam for heat treatment, 36 is an optical head, and 37 is a spindle motor.

The magneto-optical recording medium 31 is rotated at a constant speed of 2 m / sec or more, and the heat treatment laser beam 35 having an intensity twice or more the normal recording laser power is applied to the inter-recording track portion 3.
The heat treatment is performed while controlling the optical head 36 so as to irradiate only No. 3 to form the heat treated recording track portion 33a.

At this time, FIG. 4 shows the Kerr hysteresis loop in the direction perpendicular to the film surface in the inter-recording track portion 33a and the recording track portion 34 of the reproducing magnetic film of the recording layer which has been subjected to the heat treatment. A portion 33a between recording tracks due to heat treatment
It can be seen that the Kerr rotation angle and the perpendicular magnetic anisotropy of No. 1 are significantly deteriorated.

Further, FIG. 5 shows 50 dB when a recording magnetic domain recorded with a recording laser power 1.3 times the normal one is erased with the normal erase laser power during the heat treatment of the magneto-optical recording medium.
The conditions under which the above erasing rate is obtained and the conditions under which the polycarbonate substrate is damaged are shown. 2m / se from Fig. 5
It can be seen that the heat treatment of the recording layer can be performed without causing harmful damage even if a plastic substrate is used by heat treatment at a laser linear power of c or more and a laser power of 2.5 times or more the usual laser power.

By the way, in this embodiment, since each magnetic film constituting the recording layer has the same temperature at which its magnetic characteristics are deteriorated, the above-mentioned manufacturing method is used to make a space between the recording tracks of all the magnetic films. Although the magnetic characteristic of the portion located is deteriorated, when the deterioration temperature of each magnetic film is different, only the magnetic film having a low deterioration temperature can be deteriorated by the above manufacturing method.

By the above method, the reproducing magnetic film 1 shown in FIG.
4. The perpendicular magnetic anisotropy of the portions 14a, 15a and 16a located between the recording tracks of the transfer magnetic film 15 and the recording magnetic film 16 is deteriorated.

Information is thermomagnetically recorded as the recording magnetic domains 18 of the recording magnetic film 16 under the recording magnetic field 10. The recording magnetic domains 18 of the recording magnetic film 16 are transferred to the reproducing magnetic film 14 via the transfer magnetic film 15. The magnetization of the reproduced magnetic film 14 that has been transferred is aligned with the magnetization direction of the recording magnetic film 16. However, the portions 14a, 15a and 16a located between the recording tracks of the reproducing magnetic film 14, the transfer magnetic film 15 and the recording magnetic film 16
Since the perpendicular magnetic anisotropy is deteriorated, the same magnetic domain as the recording magnetic domain is recorded in this portion 16a even under the recording condition in which the recording magnetic domain 16 is formed by protruding the recording track of the recording magnetic film 16 during recording. Is not formed, and the reproducing magnetic film 1 is not formed.
The polar Kerr effect of No. 4 is also very small in this portion 14a.

When this magneto-optical recording medium is reproduced, the temperature of the recording layer 18 rises due to the irradiation of the reproducing light. Since the intensity of the focused reproduction light has a Gaussian distribution and the magneto-optical recording medium moves with respect to the reproduction light, the temperature distribution in the reproduction light spot is rearward from the vicinity of the center of the reproduction light spot as shown in FIG. A high temperature portion of Tc2 or more is formed by shifting. That is, the Curie temperature Tc of the reproduction light spot shown in FIG.
Since the magnetization of the transfer magnetic film 15 disappears in a portion of two or more, the exchange coupling between the reproducing magnetic film 14 and the recording magnetic film 16 corresponding to that portion is cut off, and the magnetization of the reproducing magnetic film 14 in that portion is blocked. Are aligned in the direction of the reproducing magnetic field 10. Further, since the polar Kerr effect of the portion 14a located between the recording tracks of the reproducing magnetic film 14 is very small, as a result, the stored information can be stored only from the portion 20 which is Tc2 or less in the reproducing light spot and which is the recording track. It can be read out as a reproduction signal. Therefore, the recording magnetic domain smaller than the size of the reproducing light spot can be reproduced without the waveform interference from the recording magnetic domains on the front and right sides, so that the S / N of the reproduction signal and the crosstalk from the adjacent track can be avoided, and the recording can be performed. Even if the erasing power varies, noise generation due to the unerased portion of the recording magnetic domain can be reduced.

The Curie temperature and the coercive force of each magnetic film forming the recording layer 19 can be relatively easily changed by selecting the composition and adding various elements having different magnitudes of perpendicular magnetic anisotropy. The optimum magneto-optical recording medium can be manufactured even if the recording / reproducing conditions required for the magneto-optical recording medium change.

In this embodiment, the substrate 12 is a polycarbonate, the protective layers 13 and 17 are SiN films, the reproducing magnetic film 14 is a GdFeCo film, the transfer magnetic film 15 is a TbFe film, and the recording magnetic film 16 is a TbFeCo film. The substrate 12 is made of another plastic or glass, the protective layers 13 and 17 are made of another nitride film such as AlN, an oxide film such as TaO ₂ or a chalcogenide film such as ZnS, or a mixture thereof. The Curie temperature and coercive force of the film and each magnetic film are Tc2 <
Other rare earth-transition metal based ferrimagnetic films or MnBi as long as the conditions of Tc1, Tc2 <Tc3 and Hc1 <Hc3 from room temperature to near Tc2 are satisfied.
A Mn-based magnetic film such as Al or a perpendicular magnetization film of another magnetic material may be used.

By the way, in the present embodiment, the perpendicular magnetic anisotropy of all three magnetic films was deteriorated in the portion located between the tracks, but the reproducing magnetic film 14, the transfer magnetic film 15, and the recording magnetic film were used. Even if the perpendicular magnetic anisotropy of the portion of at least one of the 16 magnetic films located between the recording tracks is made, the same operation can be obtained by the same flow as described in the explanation of the operation of the present invention.

[0032]

As described above, the magneto-optical recording medium of the present invention reduces the waveform interference in the recording magnetic domain and the crosstalk from the adjacent tracks to improve the recording density, and to cope with the fluctuation of the recording / erasing power. In addition, it is possible to realize high performance in which noise is less likely to occur due to the unerased portion of the recording magnetic domain.

Further, in the method for manufacturing a magneto-optical recording medium of the present invention, a magneto-optical recording medium having a structure in which a reproducing magnetic film, a transfer magnetic film and a recording magnetic film are provided as recording layers on a substrate is irradiated with laser light, By providing a structure in which only the portion of the recording layer located between the recording tracks is heat-treated, the magnetic characteristics of the portion between the recording tracks of at least one magnetic film of each magnetic film are deteriorated without damaging the plastic substrate. Thus, the magneto-optical recording medium of the present invention can be manufactured.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a magneto-optical recording medium according to an embodiment of the present invention.

FIG. 2 is a diagram showing a temperature distribution in a reproduction light irradiation region of a recording film in the example.

FIG. 3 is a schematic view of an apparatus for manufacturing a magneto-optical recording medium in the same embodiment.

FIG. 4 is a Kerr hysteresis loop characteristic diagram in the direction perpendicular to the film surface in a recording track portion and a recording track portion in the magneto-optical recording medium of the same embodiment.

FIG. 5 is a diagram showing the relationship between the heat treatment laser power and the medium linear velocity when manufacturing the magneto-optical recording medium of the present invention.

FIG. 6 is an explanatory diagram for explaining the operation of the magneto-optical recording medium of the present invention.

FIG. 7 is a block diagram of a conventional magneto-optical recording medium.

[Explanation of symbols]

10 magnetic field for recording and reproducing 11 reproducing light 12 substrate (polycarbonate resin) 13 protective layer (SiN film) 14 reproducing magnetic film (GdFeCo film) 15 transfer magnetic film (TbFe film) 16 recording magnetic film (TbFeCo film) 17 protective layer ( SiN film) 18 recording magnetic domain 19 recording layer 31 magneto-optical recording medium 32 substrate 33 portion located between recording tracks of recording layer 33a heat treated portion located between recording tracks of recording layer 34 used as recording track of recording layer Part 35 Heat treatment laser light 36 Optical head 37 Spindle motor 61 Recording and reproducing magnetic field 62 Initializing magnetic field 63 Reproducing light 64 Reproducing light spot 65 Region with temperature Tc2 or higher 66 Reproducing magnetic film 67 Transfer magnetic film 68 Recording magnetic film 69 Recording magnetic domain 71 magnetic field for recording and reproduction 72 reproduction light 73 reproduction light scan Tsu DOO 74 recording magnetic domain 75 temperature Tc or more areas 76 reproducing magnetic film 77 transfer magnetic layer 78 the recording magnetic film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Norio Miyatake 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] 1. A recording layer including a reproducing magnetic film magnetically coupled to a substrate, a transfer magnetic film, and a recording magnetic film, and a recording signal is recorded as a magnetic domain on the recording magnetic film, and the transfer is performed. A magnetic film transfers a recording magnetic domain of the recording magnetic film to the reproducing magnetic film, and the recording magnetic domain transferred to the reproducing magnetic film is converted into an optical signal by a magneto-optical effect to be reproduced as a reproducing signal. Where the Curie temperature and coercive force of the reproducing magnetic film, the transfer magnetic film, and the recording magnetic film are Tc1, Tc2, Tc3, and Hc, respectively.
1, Hc2, Hc3, Tc2 <Tc1, Tc2
<Tc3 and Hc1 from room temperature to near Tc2
<Hc3, and magnetic properties of a portion of at least one of the reproducing magnetic film, the transfer magnetic film, and the recording magnetic film located between the recording tracks are deteriorated. Magneto-optical recording medium. 2. A reproducing magnetic film, a transfer magnetic film and a recording magnetic film are perpendicularly magnetized films, and the perpendicular magnetic anisotropy of a portion of each magnetic film located between recording tracks is deteriorated. The magneto-optical recording medium according to claim 1, wherein 3. A recording on a recording layer by irradiating a magneto-optical recording medium having a recording layer composed of a reproducing magnetic film, a transfer magnetic film and a recording magnetic film magnetically coupled on a substrate with laser light. A method of manufacturing a magneto-optical recording medium, characterized in that the magnetic characteristics of at least one portion of each magnetic film located between recording tracks are deteriorated by heat-treating only the portion located between tracks. 4. A reproducing magnetic film, a transfer magnetic film, and a recording magnetic film are perpendicularly magnetized films, and the perpendicular magnetic anisotropy of a portion of each magnetic film located between recording tracks is deteriorated. 4. The method for manufacturing a magneto-optical recording medium according to claim 3, wherein