Relaxation times for magnetization reversal in a high coercivity magnetic thin film

We used a magneto-optical Kerr effect microscope to measure 180 degrees mag netization reversal in a high coercivity CoCr10Ta4 thin film subjected to n anosecond field pulses. Exponential magnetization decay occurs for pulse du ration t(p) < 10 ns followed by logarithmic decay for t(p) > 10 ns, indicat ing a crossover from nonequilibrium magnetization relaxation at short t(p) to metastable equilibrium and thermal relaxation for longer t(p). We conclu de that the nonequilibrium magnetization relaxation time (tau(n)) and that the average relaxation time of microscopic thermal fluctuations (tau(0)) is tau(n) = tau(0) approximate to 5 ns.