AN ALGEBRAIC APPROACH TO GREEN-FUNCTIONS FOR SURFACE, INTERFACE AND OVERLAYER MAGNETISM

The Gaussian elimination and back substitution formalism is employed t o study magnetic lattices involving surfaces and interfaces. On the ne arest neighbor interaction of Heisenberg model, it is shown that exact Green's functions for any spin layer can be found in analytical form. Surface and interface spin wave spectra as well as the surface magnet ization at low temperatures are calculated for systems with variable e xchange coupling strengths. The recently observed substrate-induced ma gnetization in over-layers is also found. The advantages and limitatio ns of the method. in general are discussed.