Mark Formation Mechanisms and R/W Characteristics for Gd1-xTbxFeCo/TbFe1-yCoy Films

Mark formation mechanisms and R/W characteristics of two kinds of exchange-coupled magneto-optical disks, consisting of a read layer and a write layer, were investigated using an RAY tester and a polarizing microscope. In one of the disks (a regular-mode disk), marks recorded in the read layer were transcribed to the write layer; the opposite was the case in the other disk (an inverse-mode disk). In the case of the regular-mode disks, the characteristics of the carrier levels in relation to the writing power showed two stages, corresponding to ring domains and full domains. The ring domains appeared when the write power was low, and were caused by the static magnetic field near the Tc radius in the write layer. The full domains appeared when the write power was high, because the anisotropic field in the reading layer decreased sufficiently. Only one stage was observed in inverse-mode disks. This is because the marks, which were formed by the Curie-point writing process in the write layer, were transcribed to the read layer.