Sony Corporation

Other

Yoshihiro Muto

Yoshihito Fukushima

Masatsugu Suwabe

Katsuhisa Aratani

Ken Tamanoi

Masahiko Kaneko

Ariyoshi Nakaoki

Yasuhito Tanaka

Kayoko Suzuki

Masatsugku Suwabe

A magneto-optical recording medium for recording and reproducing carriers by laser beam irradiation includes a first magnetic layer which is magnetized in the in-plane direction at room temperature and is perpendicularly magnetized at a predetermined temperature T or more; a second magnetic layer which is in contact with the first magnetic layer, has a Curie temperature Tc higher than the predetermined temperature T , and has in-plane magnetic anisotropy up to the Curie temperature Tc ; a third magnetic layer which has a Curie temperature Tc higher than the predetermined temperature T and has perpendicular magnetic anisotropy at least in a predetermined range of a temperature distribution of the magneto-optical recording medium during laser beam irradiation when reproducing; and a rare earth metal layer formed between the third magnetic layer and the second magnetic layer.

Magneto-optical recording medium having multiple magnetic layers capable of reducing reproducing laser power

A magneto-optical recording medium having a magnetic film stack structure includes a recording layer, a reproducing layer, and an intermediate layer formed between the recording layer and the reproducing layer. The intermediate layer has an easy magnetization characteristic along an in-plane direction at room temperature.

High density magneto-optical recording medium and production method thereof

In a magneto-optical recording medium including a first magnetic layer which is magnetized in a predetermined direction according to a data signal and a second magnetic layer which is magnetically connected to the first magnetic layer by exchange interaction, so that a boundary magnetic wall can exist between the first magnetic layer and the second magnetic layer, the present invention increases stability of the boundary magnetic wall formed between the first magnetic layer and the second magnetic layer and to enhance a reproduction durability as well as durability against repeated recording. The first magnetic layer and the second magnetic layer are formed by sputtering. At least one of the magnetic layers composing the first magnetic layer and positioned adjacent to the second magnetic layer is formed with a sputter gas pressure greater than the sputter gas pressure applied when forming a magnetic layer composing the second magnetic layer and positioned adjacent to the first magnetic layer.

Magneto-optical recording medium production method

This invention provides a method for producing a magneto-optical recording medium with a laminated film composed of a plurality of magnetic layers made of alloys of rare earth metals-transition metals such as a magneto-optical recording medium allowing direct overwriting through light intensity modulation and a magneto-optical recording medium allowing magnetically induced recording with super resolution, or a method for stably producing a magneto-optical recording medium excellent in performance. The method consists of using, as vaporizers to form the laminated magnetic film, three or more vaporizers including one or more vaporizers containing mainly rare earth elements and one or more vaporizers containing mainly transition metals. Then, particles ejected from a vaporizer containing mainly a rare earth metal and from two or more vaporizers containing mainly transition metals are allowed to continue to impinge onto the surface upon which the laminated film is to be formed, throughout the formation of the laminated film.

Method for producing a magneto-optical recording medium

A magneto-optical recording medium capable of performing light-intensity-modulation direct overwrite and having excellent practical characteristics is provided. A magneto-optical recording film is formed by stacking a reproducing layer made of a magnetic material from which a large Kerr rotation angle can be obtained, a memory layer made of a magnetic material having great magnetic anisotropy, an intermediate layer having small magnetic anisotropy and made of TMrich rare earth-transition metal amorphous alloy, a recording layer having a Curie temperature higher than those of the memory layer and the intermediate layer and made of TMrich rare earth-transition metal amorphous alloy, a switching layer made of a magnetic material having a Curie temperature lower than that of the recording layer and an initializing layer made of a magnetic material having a Curie temperature higher than those of the reproducing layer, the memory layer, the intermediate layer, the recording layer and the switching layer.

Rewritable high density magneto-optical disk

The present invention provides a method for producing a magneto-optical recording medium capable of optical intensity modulation direct overwriting, which method enables to easily form an initialization layer having an excellent stability against the magnetization inversion during the optical intensity modulation direct overwriting. When producing a magneto-optical recording medium at least a memory layer 1 which is magnetized according to a recording signal, a recording layer 2 whose magnetization direction is temporarily changed according to a recording signal during a recording, a switch layer 3 which is temporarily demagnetized during a recording, and an initialization layer 4 whose magnetization direction is not changed during a recording; the memory layer 1 is formed by forming at least a first magnetic layer 1a having a residual magnetization Mr smaller than a saturation magnetization Ms and a second magnetic layer 1b having a ratio Mr/Ms between the residual magnetization Mr and the saturation magnetization Ms greater than that of the first magnetic layer. Moreover, when forming the second magnetic layer 1b, an external magnetic field is applied almost in the vertical direction to the film surface.

The present invention adopts as the basic structure of its thermomagnetic recording medium an arrangement consisting of a first and a second magnetic thin film having perpendicular anisotropy and a third magnetic thin film having in-plane magnetic anisotropy or small perpendicular magnetic anisotropy interposed therebetween, formed into a laminated structure by being magnetically coupled to the adjoining films in turn, modulates and switches, in accordance with information to be recorded, a first heating condition and a second heating condition, with the medium applied with a predetermined external magnetic field H.sub.ex in the direction perpendicular to the plane of the film, the first condition being that for raising temperature of the medium to a first temperature T.sub.1 which is virtually above the Curie temperature T.sub.C1 of the first magnetic thin film and not causing reversal of the magnetic moment in the second magnetic thin film and the second condition being that for raising temperature of the same to a second temperature T.sub.2 which is virtually above the Curie temperature T.sub.C1 and sufficient to cause reversal of the magnetic moment in the second magnetic thin film, to thereby form an information bit (magnetic domains) in the first magnetic thin film, and adapts during the course the medium is cooled from the heated states such that two states established by the different relationships between the directions of magnetization of the first and second magnetic thin films are finally formed whereby the recording of the information is performed to achieve overwriting.

Thermomagnetic recording method using a recording light power modulated

A magneto-optical recording apparatus records information on a magneto-optical recording medium composed of a memory layer and a recording layer which are disposed on a substrate, each comprising a magnetic thin film of amorphous-rare-earth transition-metal alloy. The memory and recording layers are magnetically coupled directly, or through an intermediate layer therebetween, to each other under an exchange force. A recording magnetic field generator such as a permanent magnet or an electromagnet applies a recording magnetic field to the magneto-optical recording medium, and an initializing magnetic field generator such as a permanent magnet or an electromagnet applies an initializing magnetic force to the magneto-optical recording medium. The initializing magnetic field generator has a magnetic pole confronting a surface of the magneto-optical recording medium. The initializing magnetic force comprises a magnetic field H.sub.V directed perpendicularly to the surface of the magneto-optical recording medium, and a magnetic field H.sub.H directed along the surface of the magneto-optical recording medium. The magnetic fields H.sub.V, H.sub.H are defined as follows:

Growing community of inventors

Miyagi, Japan

Yoshihiro Muto