Magnetooptical recording medium allowing overwriting with two or more magnetic layers and recording method utilizing the same

摘要

This apparatus and system comprise a medium (11) provided with a first magnetic layer (2) and at least a second magnetic layer (3) having a higher Curie point temperature (Tc) and a lower coercive force (HL) than those of said first magnetic layer and being exchange coupled with said first magnetic layer satisfying a relation: $wherein\; HH\; is\; the\; coercive\; force\; of\; the\; first\; magnetic\; layer;\; HL\; is\; the\; coercive\; force\; of\; the\; second\; magnetic\; layer;\; Ms\; is\; the\; saturation\; magnetization\; of\; the\; second\; magnetic\; layer;\; h\; is\; the\; thickness\; thereof;\; and\; sigma\; w\; is\; the\; magnetic\; wall\; energy\; between\; the\; first\; and\; second\; magnetic\; layers,\; means\; (6,14,22)\; for\; irradiating\; the\; medium\; (11)\; with\; a\; modulated\; light\; beam\; and\; means\; (24)\; for\; applying\; magnetic\; fields\; to\; the\; medium.$