Propagation of magnetostatic surface waves across a large amplitude grating

Abstract

The dispersion relation is obtained and solved for magnetostatic (Damon-Eshbach) surface waves propagating normal to the grooves of a large amplitude grating ruled on the surface of a semi-infinite ferromagnet. It is assumed that a static external magnetic field, as well as the saturation magnetization in the ferromagnet, is oriented parallel to the grooves of the grating. The dispersion curve consists of many dispersive branches in the presence of the grating, in contrast with the single, non-dispersive branch obtained in the case of a planar surface. Also, in contrast with Damon-Eshbach surface waves on a planar surface, which propagate in only one direction normal to the externally applied magnetic field, and not in the reverse direction, magnetostatic surface waves on a grating propagate in both directions normal to the field. Moreover, their dispersion curves are reciprocal, i.e., ω(−k) = ω(k), where ω(k) is the fre- quency of the surface wave of one-dimensional wave vector k.