Matsushita Electric Industrial Co., Ltd.

Yoshihiko Kudoh

Masahiro Birukawa

Yasumori Hino

Norio Miyatake

Yuuichi Fukamachi

Motoyoshi Murakami

Hidetsugu Kawabata

Masakazu Yamamoto

A magneto-optical recording medium including a recording layer for recording information and a substrate for supporting the recording layer is disclosed. The recording layer includes: a recording magnetic film for recording the information, the recording magnetic film being formed of a perpendicular magnetic anisotropy film; and a readout magnetic film for optically reading out the information, the readout magnetic film being capable of being magnetically coupled with the recording magnetic film by an exchange-coupling force. The composition of the readout magnetic film may be chosen such that the exchange coupling force from the recording magnetic film does not affect the magnetization around the surface of the readout magnetic film on the side on which the readout light is incident.

Magneto-optical recording medium having a GDFECO readout magnetic film

A magneto-optical recording medium including a recording layer for recording information and a substrate for supporting the recording layer is disclosed. The recording layer includes: a recording magnetic film for recording the information, the recording magnetic film being formed of a perpendicular magnetic anisotropy film; a readout magnetic film for optically reading out the information, the readout magnetic film being capable of being magnetically coupled with the recording magnetic film by an exchange-coupling force; and a controlling magnetic film, provided between the recording magnetic film and the readout magnetic film, for controlling the exchange-coupling force. The controlling magnetic film has in-plane magnetic anisotropy at room temperature.

Magneto-optical recording medium

A magneto-optical recording medium including a recording layer for recording information and a substrate for supporting the recording layer is disclosed. The recording layer includes: a recording magnetic film for recording the information, the recording magnetic film being formed of a perpendicular magnetic anisotropy film; a readout magnetic film for optically reading out the information, the readout magnetic film being capable of being magnetically coupled with the recording magnetic film by an exchange-coupling force; and a controlling magnetic film, provided between the recording magnetic film and the readout magnetic film, for controlling the exchange-coupling force. The controlling magnetic film has in-plane magnetic anisotropy at room temperature, thereby suppressing the exchange-coupling force between the recording magnetic film and the readout magnetic film, and when the temperature of the controlling magnetic film reaches a predetermined temperature by a readout light irradiation, the controlling magnetic film stops the suppression of the exchange-coupling force, whereby the information recorded in the recording magnetic film is magnetically transferred to the readout magnetic film.

A read-only disk and a write-only disk recorded at high density having a magneto-optical film differing in coercive force depending on the information to be recorded disposed on a substrate. In the read-only and write-once disks, signals can be read employing only part of the irradiation beam, and thus super-resolution reading is realized.

Magnetic recording medium and method of fabricating the same

Magneto-optic recording medium and method of fabricating the same

A magneto-optical recording medium having a recording layer which has a first magnetic film, a second magnetic film and a third magnetic film in this order from a laser beam incident side, in which the second magnetic film has a perpendicular anisotropy in a temperature range from room temperature to a Curie temperature, the first magnetic film has an in-plane anisotropy when there is no temperature increase by the irradiation of a laser beam or a perpendicular anisotropy when the temperature is raised by the irradiation of the laser beam, and an exchange coupled force is present between the first magnetic film and the second magnetic film.

Magneto-optical recording medium and recording and reading out process

A magneto-optical recording medium includes at least a reading layer and a writing layer on a substrate. A track guide groove is formed in the medium so as to include in-groove portions and on-land portions. Only a portion where a temperature has been raised by optical beam irradiation is read, while a domain of a writing layer is copied on the writing layer, whereby a writing/reading operation can be effected with narrower track pitches. By this arrangement, there can be realized a narrow track pitch which is narrower than the diameter of a laser beam.

Rewritable disk-shaped optical recording medium

An optical disk formation member has a center and an outer periphery. A tracking guide groove formation portion and a prepit formation portion are provided on the member. A first land plane on an internal peripheral side of the prepit formation has a depth that is different from a second land plane on the external peripheral side of the prepit formation portion. The second land plane, furthermore, is deeper than the first land plane on the internal peripheral side of the prepit formation portion.

Optical disk formation member for making an optical disk substrate

A method of making a stamper uses a photoresist disk cut by the application of a laser beam on the land planes thereof, or a stamper which is different in depth between the land plane on the internal peripheral side with respect to the prepit portion and the land plane on the external peripheral side. A method of making an optical disk substrate includes the steps of using a stamper, and molding a transparent plastic material with an injection molding method. A stamper capable of sufficiently transferring the prepits and guide grooves on the optical disk substrate with the correction of right and left inequality of the prepits, and the method of making it, and a superior optical disk substrate and a method of making it can be realized.

Optical disk substrate with land planes of uniform height

A magneto-optical recording medium operable with a low external magnetic field intensity during recording and erasing and attenuating a variation in the external magnetic field intensity comprises a magneto-optical recording layer and protective and reflective layer provided adjacent to the magneto-optical recording layers, each of which has a size of microstructures (which are associated with the non-uniformity in composition, density, crystallizability, and the like and visible under a transmission electron microscope) less than the width of a magnetic domain wall in the magneto-optical recording layer.

Magneto-optical recording medium and method of manufacturing same

The present invention relates to a magneto-optical recording medium, in which are provided at least a reading layer and a writing layer on a substrate. A track guide groove is formed in the medium so as to include in-groove portions and on-land portions. Pits are formed on a portion along the track longitudinally adjacent where an in-groove portion and where no guide groove exists. Pits are also formed in an on-land portion between the in-groove portions of the track guide groove. Only a portion where a temperature has been raised by optical beam irradiation is read, while a domain of a writing layer is copied on the writing layer, whereby a writing/reading operation can be effected with narrower track pitches.

Optical recording disk, and recording/reading apparatus using same

A magneto-optical recording medium comprises a base film having a certain crystal plane oriented in parallel to a substrate and a recording film formed on the base film. The recording film is composed of plural pairs of Mn alloy group magnetic thin film layer having a C-axis-oriented crystalline magnetic anisotropy and a nonmagnetic thin film layer having an interatomic spacing approximate to that of the base film, alternately laminated each other, so that the Mn alloy group magnetic film having a C-axis-oriented crystalline magnetic anisotropy is epitaxially grown on the substrate at a low temperature through the base film with high thermal stability and great magneto-optical effect.

By performing a recording operation and an erasing operation while oscillating a position of a laser beam irradiation on an optical recording medium in a direction perpendicular to the track direction, an improvement in the S/N ratio during reproduction and a reduction of jitter in the detecting signal are attained. As an element for oscillating the laser beam irradiation position in the direction perpendicular to the track direction, an acousto-optical deflector or an electro-optical deflector is used.

Magneto-optical information recording method and apparatus in which a

In a method of producing a deposition film of a composite material, a plurality of sputtering targets each containing one of a plurality of different components are disposed separately in a vacuum chamber. A substrate is subjected to sputtering from the sputtering targets while being moved at an adequately high speed relative to a deposition rate from each sputtering target so that extremely thin layers of the respective components are sequentially stacked repeatedly a plurality of times to thereby form a deposition film of a composite material in which the plurality of different components are mixed uniformly.

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Yawata, Japan

Yoshihiko Kudoh