Temperature dependence of magnetization reversal in TbFeCo films

The magnetization reversal process has been studied in a series of four TbFeCo films over the temperature range 300-460 K. The films were characterized by time decay, dynamic coercivity, Kerr imaging, and torque measurements. For a film with a sputter-etched SiN underlayer, the reversal process at low temperatures was dominated by nucleation followed by rapid domain wall motion. The low temperature relaxation curves for this sample were analyzed using a Fatuzzo model. At high temperatures, the Fatuzzo model did not apply. For the other films, with no etching, relaxation curves were logarithmic at all temperatures. All activation volumes increased with increasing temperature and decreased with increasing sputtering pressure. The magnetic anisotropy direction changed from perpendicular to in-plane as the argon sputtering pressure was increased.