Thermo-magneto-optical memory device and recording medium therefor

Claim 1

A thermomagnetooptical memory device comprising: a recording medium having a magnetooptically active layer on a substrate, said magnetooptically active layer having first and second opposite surfaces; means for producing a beam of laser radiation, said beam having a wavelength λ, said beam being incident on the first surface of the magnetooptically active layer; means for focusing the beam of laser radiation onto selected locations on the recording medium; and magnetooptical detection means arranged to receive laser radiation reflected from the recording medium; characterized in that: the recording medium further comprises a reflective layer for reflecting laser radiation incident thereon, said reflective layer being arranged facing the second surface of the magnetooptically active layer; the magnetooptically active layer consists essentially of a polycrystalline Fe +3 -based oxidic material with a spinel structure said layer having a thickness such that destructive interference is produced between laser radiation reflected at the first surface of the magnetooptically active layer and laser radiation reflected by the reflective layer, the radiation reflected by the reflective layer passing through the magnetooptically active layer twice; and the recording medium further comprises a thermally-insulating dielectric layer arranged between the second surface of the magnetooptically active layer and the reflective layer, said dielectric layer being transparent to radiation of wavelength λ and having an optical thickness equal to an integral multiple of λ/2.