In-plane magnetic anisotropies inFe3O4films on vicinal MgO(100)

Abstract

Ferromagnetic resonance was used to study the influence of vicinal (miscut) angle and film thickness on in-plane fourfold and uniaxial magnetic anisotropies in epitaxial ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$ films grown on vicinal MgO(100) surfaces. The in-plane fourfold anisotropy constant ${K}_{4\ensuremath{\parallel}}$ is approximately the same for all films but the dominant in-plane uniaxial constant ${K}_{2\ensuremath{\parallel}}$ varies linearly with the inverse ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$ layer thickness and approximately quadratically with the vicinal angle. A second, weaker, in-plane uniaxial term is evident for the film on a larger miscut (10\ifmmode^\circ\else\textdegree\fi{}) substrate. The easy axis of the dominant in-plane uniaxial term is perpendicular to the step edges. The dominant in-plane uniaxial anisotropy has one term inversely proportional to the film thickness that is associated with anisotropy localized at the interface and a second term that is independent of film thickness; the latter may arise from the preferential alignment of antiphase boundaries with the step edges.