Features of the scattering of exchange spin waves by layer and superlattice of biaxial ferromagnets

Abstract

The paper studies the scattering of exchange spin waves at the interface of biaxial magnetic materials with a uniform ground state and describes a method for finding the reflection and transmission coefficients from an isolated boundary, layer, and multilayer structure of such materials. The breaking of the axial symmetry of the precession of magnetization leads to the formation of surface exchange waves at the interface. These waves correspond to the imaginary roots of the characteristic equation and have the opposite to the bulk waves chirality of precession. Taking them into account aligns the number of boundary conditions and unknown amplitudes. The scattering coefficients are obtained by expanding over a small ellipticity parameter in the zero and first approximations. A comparison with the exact solution was made. It is shown that the frequency dependence of the reflection coefficient can be non-monotonic, and it can turn to zero, which corresponds to the equality of the wave impedances of the adjacent media.