Dynamic information storage or retrieval – Storage or retrieval by simultaneous application of diverse... – Magnetic field and light beam
Patent
1993-04-20
1994-10-11
Nguyen, Hoa T.
Dynamic information storage or retrieval
Storage or retrieval by simultaneous application of diverse...
Magnetic field and light beam
360114, G11B 1304
Patent
active
053553543
ABSTRACT:
A non-overwritable recording apparatus comprises a magnetooptical recording media including at least first and second exchange-coupled layers having perpendicular magnetic anisotrophy, the Curie temperature of the second layer being higher than that of the first layer. The direction of magnetization of the second layer is aligned in a predetermined direction, without changing the direction of magnetization of the first layer, and the direction of magnetization of the first layer is aligned in a direction such that an interface magnetic wall is formed between the first and second layers in at least each recording portion of the medium. While the medium is rotated, a laser beam is radiated on the medium and is pulse-modulated, according to information to be recorded, between a first intensity level which imparts to a recording portion a temperature at least as high as the Curie temperature of the first layer and lower than that of the second layer and which thereby forms a mark having no interface magnetic wall between said first and second layers, and a second intensity level, including zero-level, which imparts to a recording portion a temperature lower than a lowest temperature at which the interface magnetic wall disappears, whereby the mark is not formed. In a modification, the first intensity level imparts to a recording portion a temperature lower than the Curie temperature of the first layer and at least as high as a lowest temperature at which an interface magnetic wall between the first and second layers disappears.
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patent: 5210724 (1993-05-01), Kobayashi
Matsumoto Hiroyuki
Saito Jun
Nguyen Hoa T.
Nikon Corporation
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