Dynamic properties of domain wall motion in permalloy films

Domain wall motion in Permalloy films was experimentally studied in pulsed magnetic fields of various pulselength, and it was found that the Bloch-wall displacement is not proportional to the pulselength in the nanoseconds region. The results suggest that the instantaneous wall velocity is not constant for high field, and that the fast wall motion just after the field starts is damped rapidly and then relaxes to steady slow wall motion. This is discussed from the damped and clamping-free domain wall motion theory.