Anomalous surface deceleration of a domain wall in an amorphous ferromagnet

On soft magnetic amorphous specimens, a rapid decrease in the surface ampli tude of 180 degrees domain wall oscillations relative to the bulk amplitude is observed with increasing frequency of the magnetizing field. The dynami cs of the domain wall is studied by a magnetooptical method at the specimen surface and by the induction method in the bulk. The results of the experi ment disagree with the theory, which takes into account the effect of eddy currents and predicts that, with increasing frequency, the surface amplitud e of the domain wall oscillations should decrease slower than the bulk ampl itude. The observed behavior of the domain wall is explained by its interac tion with macroscopic defects at the specimen surface. This interaction giv es rise to unsteady chaotic surface wall displacements, which lead to an in crease by several orders of magnitude in the effective surface damping para meter in the Landau-Lifshits equation. (C) 2000 MAIK "Nauka/Interperiodica" .