Evidence for strong surface magnetoelastic anisotropy in epitaxial Cu/Ni/Cu(001) sandwiches

Measurements of effective magnetic anisotropy energy of epitaxial Cu/Ni/Cu(001) sandwiches are analyzed as a function of Ni film thickness h. The magnetization easy axis is perpendicular to the films for $20<h<140$ {}. The magnetic anisotropy is best described by inclusion in the effective anisotropy energy of the strain-dependent magnetic surface anisotropy term, predicted by the strain-dependent N\'eel model, along with the usual magnetostatic, magnetocrystalline, and bulk magnetoelastic energies. The surface magnetocrystalline and surface magnetoelastic anisotropy energies of the Ni/Cu(001) interface are determined to be +0.9 erg/cm² and -52 erg/cm², respectively. The effective magnetoelastic coupling coefficient (bulk plus surface) of Cu/Ni/Cu(001) is predicted to change sign at $h=80$ {}. The two observed magnetization easy-axis reversals are also well described by this model.