MAGNETOOPTICAL RECORDING MATERIALS AND TECHNOLOGIES

Thin films of amorphous rare-earth transition-metal alloys represent a suitable class of materials for magneto-optical information storage. They are ferrimagnets and exhibit a uniaxial magnetic anisotropy. The magnetic and magneto-optical properties can be well tailored by the composition as well as the deposition conditions. The information is stored via magnetic domains, which can be written by a thermomagnetic switching process. The reading process utilizes the magneto-optical Kerr effect. At present, the most prominent candidates for device applications are GdTb-Fe and Tb-FeCo alloys. High read-out efficiencies and a long-term stability of the active magneto-optical medium can be realized using a multileyer structure. Thus carrier-to-noise values up to 61 dB (30 kHz bandwidth) have been achieved. Other media like ferrimagnetic oxides and Pt-Co multilayers are also discussed for magneto-optical recording. © 1990.