THERMAL-ACTIVATION AND SWITCHING IN C-AXIS ALIGNED BARIUM FERRITE THIN-FILM MEDIA

The thermal activation volume and the magnetic switching volume were m easured in c-axis uniaxially in-plane oriented barium hexaferrite thin film magnetic recording media. Excellent agreement among the experime ntal data obtained independently from the magnetic viscosity measureme nts and the measurements of the time dependence of coercivity implies that the thermally driven process is the cause of both phenomena. The presence of incoherent switching during magnetization reversal is indi cated by the in-plant angular dependence of coercivity and is believed io cause the much smaller activation volume and switching volume than the grain size as determined from a TEM micrograph.