Spin-wave theory of ferromagnetic crystals containing impurities

摘要: A spin-wave theory of ferromagnetic crystals containing a low concentration impurity atoms with different spin and exchange integrals is developed by Green function method. The one-magnon excitations calculated expanding in series powers the perturbation introduced then averaging terms over all possible configurations impurities. Those diagrams which correspond to scattering wave one atom orders are chosen, corresponding approximation for self-energy linear concentration. By an investigation poles it shown that dispersion curves waves have non-monotonic character near points energies resonance modes s, p or d types, damping, as energy, shows these points. It density states bands energy levels localized single-impurity problem non-analytic agreement general result Lifshitz.