Nanosecond pulsed field magnetization reversal in thin-film NiFe studied by Kerr effect magnetometry

Magnetization reversal has been studied in a 5 nm thick Ni80Fe20 film under the action of a pulsed magnetic field, for pulse durations between 2-102 n s. Fast pulses were applied to the sample from a thin-film microstrip trans mission line and magnetization changes were measured using a continuous wav e laser maoneto-optic Kerr effect magnetometer. The switching field was fou nd to increase as the pulse duration decreased, in qualitative agreement wi th simple models. More unusually, the switching field was also found to inc rease as a function of a quasi-static bias field in excess of the value of that bias. This effect is stronger for the shorter pulses. Evidence is pres ented which suggests that this is due to rapid relaxation of the magnetizat ion after the termination of the pulsed field.