| 摘要 |
PURPOSE:To enable many-valued recording and to increase density by subjecting 1st and 2nd magnetic films having the characteristics that the magnetic field characteristics to generate inversion nuclei invert above and below at a required temp. to recording of information respectively independently by combination of different external magnetic fields and temps. CONSTITUTION:The different external magnetic fields and temps. are applied to the two magnetic films 11 and 12 constituted of a rare earth-transition metal alloy exhibiting ferri magnetism, by which the generation or non-generation of the inversion of the magnetization in both or one of the 1st and 2nd magnetic films 11 and 12 is obviated. Overwriting between 4 states of B-E can, therefore, be executed by modulating the external magnetic field to 4 levels; -H2, -H1, H1, H2 and modulating laser power to 2 values as well. The recording of the multi-valued information is thereby enabled. |
