Giant Surface Magnetostriction: Fundamental Investigations

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9410943 R. O'Handley This research involves a series of measurements directed toward a more thorough and fundamental understanding of giant surface magnetostriction. Effective magnetoelastic coefficients can take on anomalously large values near the surface of magnetic thin films. The thickness dependence of the principal magnetoelastic coefficients is examined in epitaxial single crystal nickel/copper, nickel/silver, cobalt/copper, iron/silver, and iron/tungsten thin films. A fundamental understanding of surface magnetoelasticity is sought, particularly concerning its correct magnitude, symmetry, temperature dependence, and the physical significance of the Neel coefficients. First principle calculations for the surface magnetoelastic coefficients of materials will be compared to experimental values measured in this program. This work should provide a sound fundamental basis for creating a predictive capability with respect to the effects of different interface materials on surface magnetoelastic effects. An exchange interaction model for the extended range of the highly localized surface effect will be tested by comparing the range of the surface magnetoelastic anomaly for different metals at different temperatures. %%% These observations have important technical consequences, since it appears that the surface conditions of thin film magnetic devices are of enhanced importance in controlling magnetic properties, especially anisotropy, permeability, and noise, even in compositions of nominally zero magnetostriction. ***