Quadri-Value MO Recording Layers for Double-MAMMOS Readout Method

Double-MAMMOS is an excellent method to increase memory density for MO recording. This method modifies the usual MAMMOS technique by applying double recording layers. Written domains in each recording layer can be selectively copied and expanded in a reading layer. By this method, memory density can be doubled. However, it is necessary to record twice, recording separately into two layers. Therefore, we propose a new type Double-MAMMOS disk, applying a quadri-value recording system to write the double recording layers with a single writing process. By applying a newly designed Double-MAMMOS disk, we can obtain a high density and high performance MO disk. To satisfy both functions of Double-MAMMOS and single writing process, we adapt the dependence of magnetization on temperature of films.