OPTICAL MEMORY MEDIUM INCLUDING MULTIPLEX DATA LEVEL CONSISTING OF CO/PT MAGNETO-OPTICAL RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To enlarge coercivity and to improve the squareness characteristic of a Kerr hysteresis loop by providing a memory medium with multiple data memory levels and the memory levels consisting of transparent dielectric seed layers and a partial transparent memory layer of multilayered structure including Co/Pt alternate layers thereon. SOLUTION: This optical data memory medium includes the three data levels. The respective data levels include the seed layers 11 consisting of In and Sn oxide, the multilayered Co/Pt layers 15 and lacquer layers 18 of a UV curing type on a substrate 10 consisting of glass and polycarbonate(PC). The transmittance of light for the first data level 1 needs to be max. (at least >=40%). As a result, the laser beam arranged on one side of the disk structure penetrates the first layer and the subsequent layers. Recording or reading out is thus executed without using the excessive laser power. The desirable thickness in the case of the high-performance Co/Pt superlattice disk is >=15nm.