Unidirectional Hysteresis in Thin Permalloy Films

Abstract

A study of torque curves in thin Permalloy films with h_c>0.5, where h_c=H_c/H̄_k is reported. The behavior of a 1400 A, 77% Ni film with h_c=0.9 is discussed as a typical example. For applied fields h>0.5, the torque curves are generally complex and the discrepancies with the Stoner‐Wohlfarth (S‐W) model wide‐spread. For hhK₂, where K₂ is of the order of K₁, the anisotropy of the bulk of the film. The torque curves calculated for this model are found to agree qualitatively very well with the experimental results.