Spin wave resonance in symmetrical/asymmetrical bilayer ferromagnetic films

The dependence of spin wave resonance (SWR) frequency on the surface anisotropy, the interlayer coupling, the ferromagnetic layer thickness and the external magnetic field in the bilayer ferromagnetic film have been investigated by using the linear spin wave approximation and Green's function technique. We find that the SWR frequency of the ferromagnetic bilayer film are shifted to higher values corresponding to those of above factors, respectively. The lowest four modes can be controlled by the surface anisotropy of A, B layer and the symmetry of the film. The SWR frequency of the energetically lowest mode is no affected except for applied magnetic field. A notable rapidly increasing behavior appears in frequency with the increasing of interlayer coupling.