NOVEL DIRECT OVERWRITING TECHNOLOGY FOR MAGNETOOPTICAL DISKS BY EXCHANGE-COUPLED RE-TM QUADRILAYERED FILMS

A light-intensity-modulation method for direct overwrite using a magneto-optical disk with exchange-coupled RE-TM quadrilayered film has been developed. This film consists of a "memory layer, "a" writing layer, "a" switching layer, "and an" initializing layer." The initializing layer is used to initialize the writing layer, and the switching layer is used to switch off the coupling between the writing layer and the initializing layer above the Curie temperature of the switching layer. These two layers have made direct overwrite with only a conventional bias magnet possible.