Green function theory for a magnetic impurity layer in a semi-infinite transverse Ising model

This paper is a theoretical investigation of the possibility that localized modes can occur in association with an impurity layer embedded within a semi-infinite Ising ferromagnetic with a transverse field. Using a Green function formalism we find that, in addition to bulk spin waves, there may be localized modes associated with the impurity layer and with the surface. The modes influence one another when the impurity layer is near the surface, modifying the spin-waves' energies and the spectral intensities. (C) 2000 Elsevier Science S.V. All rights reserved.