Thermomagnetic writing in Gd-Co sputtered films

A model for thermomagnetic writing in Gd-Co sputtered films at its compensation temperature is described. In the vicinity of the compensation temperature, the films have rectangular hysteresis loops with large values of coercive force. Spots are thermomagnetically written and erased by using a He-Ne laser in conjunction with an external magnetic field, and a diameter approximately of
1.5 \sim 2 \mu
m is achieved. Photographs of spots written thermomagnetically are shown. The written domains are circular and clear in shape, and are stable. Temperature dependences of coercive force in Gd-Co sputtered films, and characters of spot diameter as a function of applied magnetic field and writing laser power are reported.