A non-overwritable recording apparatus comprises a magnetooptical recording media including at least first and second exchange-coupled layers having perpendicular magnetic anisotrophy, the Curie temperature of the second layer being higher than that of the first layer. The direction of magnetization...http://www.google.de/patents/US5355354?utm_source=gb-gplus-sharePatent US5355354 - Non-overwritable magnetooptical recording apparatus using exchange-coupled two-layered medium with interface magnetic wall
