THE ROLE OF OBLIQUE-TO-SURFACE DISPOSITION OF NEIGHBORS IN THE EMERGENCE OF SURFACE SPIN-WAVES IN MAGNETIC-FILMS

This work is aimed at a numerical investigation of the spin-wave energ ies 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 spi n model assuming exchange nearest (NN) and next-nearest (NNN) neighbou r interactions and elucidate the role of the geometrical disposition o f the NN and NNN neighbourhoods for the emergence of the surface spin- waves. The necessary condition for the emergence of the surface spin-w aves is turned out to require the bonds to be cut at the surface obliq uely thereto irrespective of whether these ''oblique'' interactions ar e of the NN or NNN type.