Magnetoelastic Sensitivities in Evaporated and Electrodeposited Permalloy Films

When a magnetostrictive Permalloy film is stressed in the direction of its preferred axis of magnetic orientation, an effective anisotropy is induced in the film causing a change in measured Hk. Magnetoelastic measurements were made on evaporated and plated films 100–4000 Å thick and varying in composition from 70% Ni, 30% Fe to 85% Ni, 15% Fe. Composition was determined by x-ray fluorescence. It was found that the magnetoelastic coupling constant B = (2/M) (dHk/de) was significantly less for plated than for evaporated films of the same composition. There is evidence of both intercrystallite or internal crystallite slip and film-to-substrate slip, but neither is large enough to account for the observed differences.