Effect of Magnetic Annealing on Plated Permalloy and Domain Configurations in Thin-Film Inductive Head

Abstract

The magnetic annealing behavior of electroplated. 2.00 μm thick, NiFe films containing nominally 82% Ni, in the temperature range from 100 to 500°C, was investigated through characterization of the structural properties of full films and the domain configurations of films shaped like an inductive-head yoke. A transition in the magnetic properties of the films was observed in the temperature regime of 350-450°C. Concomitant changes in film stress from 0.2 to 1.4 GPa and in magnetostriction from -2.2 to -3.5 x 10^-6 were measured across the transition. Transmission electron micrographs and X-ray diffraction analysis showed that recrystallization with (111) texturing and extensive grain growth took place at the transition temperature. Kerr microscopy demonstrated that the favorable domain configuration produced in an as-plated test device could be maintained up to the transition temperature. At a higher annealing temperature, the domains transformed into a fine-sized, isotropic configuration which could be induced by the high magnetoelastic energy associated with the highly tensile stress caused by annealing in the magnetostrictively negative films. © 1991 IEEE