Abstract
A method is proposed to simulate the formation process and the shape of a magnetic domain on a moving magneto-optical disk. It is assumed that the direction of the force acting on the domain wall is perpendicular to the isothermal line of the critical temperature. Slicing lines perpendicular are taken at regular intervals to this isotherm, and by applying the one-dimensional bubble model the wall position on each slicing line is determined. Connecting the wall positions in each time frame the evolution of the domain shape in the formation process is obtained. By applying this method to Tb 23 Fe 77 thin film, it is found that the domain wall in Tb 23 Fe 77 thin film on a moving disk was first pinned in the cooling region which was the leading region of laser exposure on the disk, then the pinned wall expanded toward the heating region, and a closed domain was formed after the laser was turned off.