Slow wall motion in oxidized permalloy films

Abstract

Slow domain wall motion, persisting to liquid helium temperatures, is reported for an oxidized permalloy thin film. Films protected from oxidation or reduced in dry hydrogen after oxidation fail to exhibit this phenomenon at any temperature between 300 and 5 °K. Observations are made using the magneto‐optic Kerr effect and the motion is also shown directly by a lapsed‐time photographic technique. The behavior is closely correlated with the hystersis loop contraction characteristic of the oxidized film at very low temperatures. Measured slow wall velocities range from 10−1 to 10−3 cm/s; the logarithm of the velocity varies linearly with the applied magnetic field, with a slope that increases with increasing temperature.