Generalized Model of an Anisotropic Ferromagnet with Two Spins Der Site. Magnetic Excitations

Abstract

In this paper we concentrate on the model Hamiltonian of the form where S . a r e spin 1/2 operators at the f-th site of the i-th electron (i = 1, 2), J 0 is the intersite exchange interaction, p = I + 2E, q = I -2E, r = I + 2D, I>J(O) is the isotropic part and 0 < E < D are the anisotropic parts of the intrasite exchange interaction, h represents an external magnetic field applied along the z-direction, and k is the exchange-anisotropy parameter (0 consider the above p, g, r in order t o compare the obtained results with those already known. Using the s a m e method /I/, where the simpler c a s e with E = 0 has been considered, we find the eigenstates of the single-ion effective-field