Spin polarization of vanadium overlayers on a semi-infinite tantalum substrate

We investigate the substrate bandwidth effect on the onset of magnetism in V overlayers. The local magnetic moments and magnetic order at the V/Ta interface of ultrathin V films is studied. Different crystallographic directions (001),(011) and (111) have been considered. The magnetism is described within a real-space tight-binding approach ill the unrestricted Hartree-Fock approximation of the Hubbard Hamiltonian. The density of states has been calculated within the recursion technique. The onset of. magnetism depends strongly on the faces considered. Magnetism is more pronounced for the (001) surface and is found to decrease when V is allowed to relax in order to recover its bulk volume. The magnetic moments of the surface layers are strongly enhanced by addition of more V layers. A sizeable induced moment appears in the Ta interface layer which decreases by addition of more V layers. The same behavior is shown to occur in the Nb substrate but it is more pronounced as compared to that of Ta. This behavior is expected since the bandwidth of Nb is smaller than that of Ta and their lattice parameters are approximately the same. (C) 1997 Elsevier Science B.V.