Magnetoelastic effects in, and critical compositions for, permalloy thin film devices

Abstract

Residual elastic stresses are always present in the thin films used in various devices. The sign and magnitude of the film stress are for the most part determined by the film deposition parameters, i.e., substrate temperature, kind of substrate, deposition rate, and method of deposition. Stresses of about 109-1010 dynes/cm2, compressive or tensile, are often observed. In magnetic thin films these stresses interacting with the magnetostriction induce a magnetoelastic anisotropy which can and does influence the performance of magnetic thin film devices. In this report, we use the expression for the magnetic anisotropy energy which includes the magnetoelastic contribution, and this is used to show how the magnetoelastic anisotropy can influence device performance. We also show how the inclusion of the magnetoelastic energy in Hubert's theory of Bloch domain wall energy as a function of film thickness predicts domain wall instabilities.