Numerical Analysis of Magnetization Reversal in TbCo Magneto-Optical Recording Disks

Thermo-magnetically reversed domain sizes in TbCo magneto-optical disks have been numerically analyzed. The recorded domain radii were derived from calculations of the partial differentials of magnetic energies at domain walls, according to Huth´s model. Disk samples were prepared and the measured thermo-magnetic properties were used in calculations. A relative value for the domain wall energy was obtained using the mean field theory. Its absolute value was adjusted so that calculated and measured threshold recording powers coincided. Recorded domains in disk media were observed with an Ar laser scanning polarized light microscope. The radii of the domains were compared with calculated values. This numerical analysis yielded fairly good estimates for rather high powers, whereas the calculated radii were much smaller than observed values near the threshold recording power.