Thermomagnetic writing in Tb-Fe films

Thermomagnetic writing in amorphous Tb-Fe films prepared by thermal evaporation or rf-sputtering is described. These films have a low Curie temperature (75°C) and large values of coercive force over the wide range of temperature. Spots are thermomagnetically written and erased by using a He-Ne laser in conjunction with external magnetic field, and 1 ∼ 2 micron spots are written stably with low laser power. At this writing, a new property was found, that is, the Kerr contrast of the spots gradually varies with a value of the external magnetic field. Temperature dependences of coercive force and magnetization, spot diameter as a function of writing laser power and the Kerr contrast of spots as a function of external magnetic field are reported.