Theory of dipole-exchange spin-wave propagation in periodically corrugated films

We present a theory of spin-wave normal modes of a ferromagnetic film with periodically corrugated surfaces in Damon-Eshbach geometry. Two possibly different corrugations on the upper and lower film surface are considered. Both the surface mode and perpendicular standing modes are studied with the partial-wave method, adapted to take into account the modified boundary conditions, within the limit of validity of the Rayleigh’s hypothesis. The theory, particularly suited to the case of shallow gratings, shows that the effect of corrugation on the dispersion curves is enhanced on asymmetrical structures, such as films with a sinusoidally corrugated top surface and flat bottom.