| 摘要 |
A magnetooptical disk includes a thermal diffusion layer to suppress thermal transmission between adjacent information tracks. The information tracks are formed within the magnetooptical disk along respective land portions or groove portions having a difference in grade. During recording and erasing of the magnetooptical disk, the land portions and groove portions may be changed with identical power levels. The thermal diffusion layer diffuses heat generated by irradiation of a laser beam. A protective layer is formed over the thermal diffusion layer and a recording layer which records various bits of information is formed over the protective layer. |
