Modification of the domain wall structure and generation of submicron magnetic formations by local optical irradiation

Experimental and theoretical investigations are made of the generation of v ertical Bloch lines in a magnetic iron garnet film exposed to pulsed optica l radiation. High-speed photography and anisotropic dark-field microscopy a re used to study characteristic features of the generation of Bloch lines a nd domain structure relaxation processes after the local action of a laser pulse. Optimum optical irradiation parameters to ensure the controlled gene ration of Bloch lines are established. A theoretical model is developed whi ch links the generation of Bloch lines to the migration of domain walls ind uced by local changes in the distribution of the degaussing fields caused b y a reduction in magnetization with temperature at the optical radiation fo cusing point. The experimental results indicate that the controlled formati on of magnetic structures smaller than or of the order of 0.1 mu m by local optical irradiation is quite feasible. (C) 2000 MAIK "Nauka/Interperiodica ".