Ac susceptibility and domain-wall dynamics in iron-based amorphous ribbons

The ac susceptibilities and domain structures of iron-based amorphous ribbons have been studied in as-quenched, zero-field annealed, and field annealed states. The eddy-current analysis indicates that the low-field susceptibility always has roughly equal contributions from domain-wall displacements and domain magnetization rotations. Anomalous fluctuations of susceptibility have been found which are attributed to a repeated spontaneous process of domain wan disaccommodation due to local directional ordering and small thermally activated reconstruction in domain structure.