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

Magnetization reversal has been studied in a 5 nm thick Ni sub 80 Fe sub 20 film under the action of a pulsed magnetic field, for pulse durations between 2-102 ns. Fast pulses were applied to the sample from a thin-film microstrip transmission line and magnetization changes were measured using a continuous wave laser magneto-optic Kerr effect magnetometer. The switching field was found to increase as the pulse duration decreased, in qualitative agreement with simple models. More unusually, the switching field was also found to increase 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 presented which suggests that this is due to rapid relaxation of the magnetization after the termination of the pulsed field.