Modification of the spin-wave dispersion law in multilayer films by changes in the symmetry of the boundary conditions

Abstract

The present paper is the first attempt to study the transformation of spin-wave resonance spectra when symmetric boundary conditions are smoothly replaced by asymmetric. The transition is done by gradually reducing the thickness of one of the layers in a three-layer film. Spin deexcitation is caused by a dissipation mechanism. We find that in the transition region between symmetric and asymmetric boundary conditions the dispersion curve experiences a break, whose position depends on the degree of deexcitation (the thickness of the upper layer). The break is caused by the appearance of asymmetric transitional spin-wave modes, which cannot be excited under symmetric boundary conditions.