Spin-wave study of magnetic perpendicular surface anisotropy in single crystalline MgO/Fe/MgO films

The authors report an experimental separation of the two perpendicular surface anisotropies present in MgO/Fe/MgO epitaxial films through a careful study of inhomogeneous magnetization dynamics. This is achieved by combining the strengths of two experimental techniques: the frequency broadband capabilities of ferromagnetic resonance and the precise determination of non-reciprocal propagation via propagating spin wave spectroscopy. This new experimental approach allows to separate the top and bottom perpendicular surface anisotropies often measured together in thin films, and it provides new light into the technologically-relevant ferromagnet/MgO interfaces and their effect on spin waves.