DOMAIN NUCLEATION AND WALL VELOCITY IN AMORPHOUS TBFECO THIN-FILMS

Domain reversal processes in Si3N4-overcoated TbFeCo 800-Å-thick films have been investigated utilizing nanosecond laser irradiation and polarization microscopy. The sputter-deposited thin films are first magnetically saturated and then subjected to reversing fields of various magnitudes. The kinetics of the domain growth is measured in situ utilizing the polar Kerr effect and the nucleation is directly observed with the polarizing microscope. For low values of the reversing field, nucleation is observed to occur at defects in the thin film. In all cases studied so far, we have established that following the onset of nucleation, the reversal process occurs via domain growth. We have determined the temperature dependence of domain nucleation and wall velocity during laser annealing and the nanosecond results are discussed with reference to existing models for domain wall motion.