Seiko Epson Corporation

Satoshi Shimokawato

Hiromu Miyazawa

Toshiaki Mikoshiba

Satoshi Nebashi

Masaya Ishida

Tatsuya Shimoda

Takeo Kawase

Shoji Hoshina

Masaaki Ichikawa

Mamoru Sugimoto

Atsushi Takakuwa

Akira Aoyama

Shin Funada

Hiroshi Ito

In a magneto-optical recording medium, a first dielectric layer 12, a recording layer 13, an auxiliary recording layer 14, a second dielectric layer 15 and a reflective layer 16 are sequentially laminated on a transparent substrate 11. Recording layer 14 is formed of a rare-earth transition-metal amorphous alloy having a film thickness of about several hundreds angstroms. Auxiliary recording layer 14 is also formed of a rare-earth transition-metal amorphous alloy. However, the Curie temperature T.sub.C2 of auxiliary recording layer 14 is 10.degree. K or more higher than the Curie temperature T.sub.C1 of recording layer 13, and the film thickness of auxiliary recording layer is ultra-thin, such as, 70 .ANG. or less. Further, the squareness ratio of auxiliary recording layer 14 at the Curie temperature T.sub.C1 of recording layer 13 is 0.7 or higher. These characteristics of auxiliary recording layer 14 may be realized by selecting the composition of auxiliary recording layer 14 or by lowering the density of the layer. In addition, a transition metal, such as, Fe or Co, or a non-magnetic metal, such as, Pt, Al, Ti or Cr, or a nitride of rare-earth transition-metal amorphous alloy may be employed as the material for auxiliary recording layer 14.

Magneto-optical recording medium and method of manufacturing the same

In a magneto-optical recording medium, a protective layer 14, a first magnetic layer 11 formed of a light rare earth element-heavy rare earth element-transition metal alloy, a second magnetic layer 12 formed of a light rare earth element-heavy rare earth element-transition metal alloy, a third magnetic layer 13 formed of a light rare earth element-heavy rare earth element-transition metal alloy, another protective layer 15, and a reflection layer 16 are laminated in sequence on a transparent substrate 10. The first, second and third magnetic layers are sandwiched so as to form a recording film 17. The compositions of the first and third magnetic layers are so selected as to provide a large Kerr rotational angle in a short wavelength range (400 to 700 nm), which is high in the ratio of light rare earth element. On the other hand, the composition of the second magnetic layer is so selected as to be prominent in the characteristics for forming a perpendicular magnetized film, which is high in the ratio of heavy rare earth element. The recording film 17 formed by sandwiching the first, second and third magnetic layers has a large Kerr rotational angle in a short wavelength range as a whole, and further provides a high coercivity. The recording film 17 is formed thin (400 angstrom or less) so that light can transmit sufficiently therethrough. Further, when the three layers of sandwich structure is combined with the reflection layer 16, a more larger Kerr rotational angle can be obtained.

Magneto-optical recording medium having large kerr rotational angle in

To directly overwrite data on a magnito-optical recording medium formed of two exchange-coupled magnetic layers of a memory layer with a high coercive force and a low Curie point and a reference layer with a low coercive force and a high Curie point, an initializing magnetic field (e.g. 1000 to 5000 Oe) is applied to the medium to arrange the magnetization direction of only the reference layer; a recording magnetic field (e.g. 100 to 400 Oe) is applied and simultaneously a recording laser beam modulated according to data is irradiated upon the medium to record the data as magnetization directions of the memory layer; the initializing magnetic field is applied again to the medium to arrange the magnetization direction of only the reference layer; and a reproducing magnetic field (e.g. 1000 Oe or less) is applied and simultaneously a reproducing laser beam is irradiated upon the medium to reproduce the data. Since the reproducing magnetic field the same in direction as the recording magnetic field is applied to the medium in reproducing operation, recorded data can be stably reproduced without destruction by use of a high sensitive recording medium, in particular.

Magneto-optical recording device having recording magnetic field in the

In a magneto-optical recording medium, a protective layer 14, a first magnetic layer 11 formed of a light rare earth element--heavy rare earth element--transition metal alloy, a second magnetic layer 12 formed of a light rare earth element--heavy rare earth element--transition metal alloy, a third magnetic layer 13 formed of a light rare earth element--heavy rare earth element--transition metal alloy, another protective layer 15, and a reflection layer 16 are laminated in sequence on a transparent substrate 10. The first, second and third magnetic layers are sandwiched so as to form a recording film 17. The compositions of the first and third magnetic layers are so selected as to provide a large Kerr rotational angle in a short wavelength range (400 to 700 nm), which is high in the ratio of light rare earth element. On the other hand, the composition of the second magnetic layer is so selected as to be prominent in the characteristics for forming a perpendicular magnetized film, which is high in the ratio of heavy rare earth element. The recording film 17 formed by sandwiching the first, second and third magnetic layers has a large Kerr rotational angle in a short wavelength range as a whole, and further provides a high coercivity. The recording film 17 is formed thin (400 angstrom or less) so that light can transmit sufficiently therethrough. Further, when the three layers of sandwich structure is combined with the reflection layer 16, a more larger Kerr rotational angle can be obtained.

To directly overwrite data on a magnito-optical recording medium formed of two exchange-coupled magnetic layers of a memory layer with a high coercive force and a low Curie point and a reference layer with a low coercive force and a high Curie point, an initializing magnetic field (e.g. 1000 to 5000 Oe) is applied to the medium to arrange the magnetization direction of only the reference layer; a recording magnetic field (e.g. 100 to 400 Oe) is applied and simultaneously a recording laser beam modulated according to data is irradiated upon the medium to record the data as magnetization directions of the memory layer; the initializing magnetic field is applied again to the medium to arrange the magnetization direction of only the reference layer; and a reproducing magnetic field (e.g. 1000 Oe or less) is applied and simultaneously a reproducing laser beam is irradiate, upon the medium to reproduce the data. Since the reproducing magnetic field the same in direction as the recording magnetic field is applied to the medium in reproducing operation, recorded data can be stably reproduced without destruction by use of a high sensitive recording medium, in particular.

Magneto-optical method and apparatus for recording/reproducing data

A magnetic recording film and a magneto-optic recording system utilizing films. The film includes light and heavy rare earth elements and transition metal elements. The system can include dielectric layers and low magnetic coercivity layers in addition to the recording layer.

Magneto-optic recording systems

When data are thermo-magnetically recorded to a perpendicular magnetized film of a recording medium, it is possible to prevent unnecessary magnetic domains from being formed and unerasable magnetic domains from being produced. The medium 11 is rotated by a motor 12. When being passed through a recording field generated by a magnet 14, the medium 11 is irradiated with a recording beam generated by an optical head 13, so that data can be recorded to a perpendicular magnetized film of the medium 11 as bubble magnetic domains. Further, when the medium 11 passes through a correcting magnetic field generated by a magnet 15 disposed away from the position at which data are recorded, unnecessary and/or unerasable domains can be eliminated.

A magnetic thin film recording layer comprised primarily of a light rare earth element and a transition metal element is disclosed. Other elements are optionally included in the film. The film has an easy axis of magnetization perpendicular with respect to the surface of the film. Magneto-optic recording systems using such films are also disclosed.

A sputtering target suitable for use in preparing a magneto-optic recording medium having the composition:

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Suwa, Japan

Satoshi Shimokawato