Spin-wave impurity states in antiferromagnets

摘要: The case of a single impurity substituted in an otherwise ordered antiferromagnetic crystal is considered. effect the treated as perturbation on Hamiltonian perfect lattice. In order to write down spin-wave eigenvector for anti-ferromagnetic case, factorϕλ introduced unknown phase difference between spin deviations two sublattices. matrix perturbationV obtained explicitly site representation. perturbed Green’s function related toV by Dyson’s equation and conditions existence new states are making use cubic symmetry It seen that may lie either inside or outside continuum energies. States lying band localized characterized infinite lifetime. For which band, line width calculated.