Analyses of basic physical parameters in magneto-optic materials by means of computer simulations

Detailed descriptions of computer-assisted analyses of the thermal and magnetic properties of sputter-deposited thin films used in magnetooptic media are presented. The analyses for the thermal properties are based on estimating the temperature profile produced by the incident beam, the validity of the calculation being evaluated by comparing the recording power dependence of the material. The temperature dependence of magnetic properties such as saturation magnetization, perpendicular anisotropy and exchange stiffness constants is computer-simulated using mean field theory with the assumption of including antiferromagnetically coupled iron pairs and nonmagnetic species within the materials. The effects of the nonmagnetic species on Curie temperatures and on magnetizations are discussed. Thermal constants were roughly 1/7 to 1/5 of those of bulk materials. This is due to the reductions in both electron mobility and phonon mean free path, presumably arising from the nature of amorphous structure and scattering at the grain boundaries between the additives and Al matrix. A mean analysis using four subnetworks predicted well the temperature dependencies of saturation magnetization. The reduction of Curie temperature and magnetization with the increase of additives such as Ar is attributed to the dilution in exchange interaction among the magnetic species