Anisotropy modifications and domain-wall behavior in grooved films

Patterns of 5-μm-wide grooves on 25-μm centers were partially etched in the easy and/or hard directions in uniaxial Permalloy films; 20-μm-diameter circles or 25-μm centers were also etched. The easy direction grooves modified the anisotropy of the films to produce an NDRO behavior, while the hard direction grooves resulted in biaxial symmetry. Coercive force of the easy direction grooved films increased as a result of the lower energy of 180° walls in the thinner grooved regions. Pairs of crossties and the Bloch lines between them were confined to grooves in the hard direction. Creep sensitivity was markedly decreased in hard direction grooved films. This creep control probably results from the limitation of Bloch-line motion by the hard direction grooves, in agreement with several recent suggestions concerning the mechanism of creep in crosstie walls.