Spin configurations and spin-wave excitations in exchange-coupled bilayers

The ground-state spin configuration of antiferromagnetically coupled ferromagnetic thin films is determined by competition between anisotropies, interlayer exchange, and the applied field. A theory for spin waves is presented where both exchange and dipolar interactions are accounted for and it is shown how dramatic changes in the spin-wave frequencies can be observed by carefully choosing the experimental geometry. Also, many details of the ground-state spin configuration can be obtained by studying the behavior of the spin-wave frequencies as functions of propagation direction and applied field strength in these geometries. The results are summarized from the point of view of possible light-scattering experiments.