FERROMAGNETIC-RESONANCE SPECTRUM OF EXCHANGE-COUPLED FERROMAGNETIC BILAYERS

The technique of ferromagnetic resonance is used currently to extract quantitative information on the strength of the exchange coupling between ultrathin ferromagnetic films, possibly separated by a thin layer of nonmagnetic material. The data are analyzed frequently within a model that treats the magnetization within each film as a rigid, precessing moment. We comment on the limits of validity of this picture, and also on the nature of the boundary condition applicable at the interface between two exchange-coupled media.