| 摘要 |
PCT No. PCT/JP83/00445 Sec. 371 Date Aug. 20, 1984 Sec. 102(e) Date Aug. 20, 1984 PCT Filed Dec. 20, 1983 PCT Pub. No. WO84/02603 PCT Pub. Date Jul. 5, 1984.A thermomagnetic recording and reproducing system for use in optical magnetic disc apparatus wherein at least a first layer (1) of soft magnetic material having an easy axis of magnetization normal to the layer surface, a transparent non-magnetic intermediate layer (2), a second layer (3) of soft magnetic material having an easy axis of magnetization normal to the layer surface and a metal film or semi-metal film (4) adjacent to the second magnetized layer are superposed on one another to form a recording medium (5). In recording, a bias magnetic field is applied to the first and second magnetized layers (1) and (3) so that the magnetized layers are magnetized to have a single magnetic domain over their whole surfaces and a magnetization directed perpendicular to the layer surface. Then, a light pulse having a first wavelength of, for example, a relatively short wavelength and of which optical absorptance in the magnetized layer is relatively high is made incident on the single magnetic domain of the first magnetized film (1) to form a cylindrical magnetic domain magnetized in the direction opposite to the magnetization direction by the applied bias magnetic field, thereby recording information bits on the first magnetized layer (1). A light pulse having a second wavelength of, for example, a relatively long wavelength which passes through the first and second magnetized layers (1) and (3) is made incident on the single magnetic domain of the second magnetized layer (3) to form a cylindrical magnetic domain magnetized in the direction opposite to the magnetization direction by the applied bias magnetic field. The information is read out from the medium (5) on which the recording was made as above by utilizing the magneto optic effect.
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