The role of oblique-to-surface disposition of neighbours in the emergence of surface spin waves in magnetic films

摘要

This work is aimed at a numerical investigation of the spin-wave en- ergies and respective band structures throughout the two-dimensional Bril- louin zone in magnetic(cubic)thin films for the surface orientations sc(001), bcc(001) and fcc(001). We apply the Heisenberg localized spin model assum- ing exchange nearest(NN) and next-nearest(NNN) neighbour interactions and elucidate the role of the geometrical disposition of the NN and NNN neighbourhoods for the emergence of the surface spin-waves. The necessary condition for the emergence of the surface spin-waves is turned out to require the bonds to be cut at the surface obliquely thereto irrespective of whether these "oblique" interactions are of the NN of NNN type.