Magnetooptical disk with alumina based oxide layer

Several kinds of oxides were examined as a material for protection layer of magneto-optical disk. Aging characteristics such as transparency and crystal structure of Tb thin film sandwiched by the oxide layers were examined in order to estimate the validity of oxides. Well-known oxides such as SiO2and Al2O3, were found to be inadequate as a protection layer for the RETM film. Mixed oxids based on Al2O3were found to be one of the most suitable protection layer.