IMPROVEMENT OF MAGNETOOPTICAL PROPERTIES OF CO PT MULTILAYERS PREPARED BY SPUTTERING IN AR

We investigated methods for increasing the coercive force and the Kerr rotation angle and for reducing the Curie temperature of Co/Pt multilayers to make them suitable as magneto-optical recording media. The multilayers were prepared by magnetron sputtering using Ar gas. It was found that the coercive force increased with the magnetic flux density above the magnetron target and such an increase did not degrade the crystalline quality nor make less rectangular the Kerr hysteresis loops. The Kerr rotation angle increased when the number of layers per unit thickness was increased without changing the total Co content. The Curie temperature increased with Co content but was not affected by the number of layers. Therefore, Co content and number of layers per unit thickness were optimized in order to obtain a large Kerr rotation angle and a low Curie temperature. Moreover, read/write characteristics of a magneto-optical disk using the Co/Pt multilayer were examined: a carrier-to-noise ratio of 45 dB was obtained for a bit length of 0.76 mum.