A BETHE-LATTICE APPROACH TO THE SPIN WAVE EXCITATIONS NEAR THE INTERFACE OF TWO FERROMAGNETIC INSULATORS

The property of spin wave spectra near the interface of two ferromagnetic insulators is studied. Starting from Heisenberg model and using Bethe -lattice approximation and Green's function technique, the local density of magnon states (LDOMS) is calculated for different parameters. A gap in the LDOMS is found in certain parameter region.