Reflection of electromagnetic radiation from structured metallic magnets

We present theoretical calculations for the reflection of electromagnetic waves from structured magnetic materials which are metallic. Normally one expects that electromagnetic probes of metallic materials are not helpful because of the high background reflectivity. We show that if the electron motion can be limited by the structuring then one can see distinct features in the reflectivity which arise from the magnetic excitations. This is in sharp contrast to the case for unstructured metallic magnetic materials where the reflectivity is near unity. The calculations are carried out primarily within effective-medium theory, but by an exact calculation in a special case, we show that the general results hold true for parameters well beyond the limits of validity of effective-medium theory.