EFFECT OF COPPER LAYERS ON COERCIVE FORCE OF PERMALLOY FILMS

Three mechanism of the effect of a copper layer on the coercive force of films are studied in this work: variation in the “roughness” of the substrate; diffusion of the copper into the permalloy; variation in the energy of exchange interaction between permalloy films separated by a copper layer. It is found, that an increment of the coercive force (ΔHc) with time is directly proportional to the effective diffusion depth, Δd. The results of experimental investigations on the condensation of metallic film make it possible to single out the following stages of this process: the formation of stable nuclei, the coalescence of discrete nuclei to a continuous layer; the growth of crystallites with a further increase of the thickness of continuous films. Observation of structures of interlayers under an electron microscope indicates that in wide ranges of thickness and deposition temperatures the interlayer consists of individual stable nuclei. The presence of exchange interaction between separated magnetic layers due to their direct contact makes it possible to explain the experimental results. Copyright © 1969 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim