Magnetic interactions between small Ni clusters

We have calculated the magnetic moment per atom, μ̄, of symmetric nickel cluster-dimers NiN–NiN as a function of cluster–cluster distance D and cluster size N. The spin-polarized electronic structure has been calculated with a self-consistent tight-binding method considering the 3d, 4s and 4p valence electrons. We have analyzed the partial sp and d contributions to μ̄. The d component shows a monotonic behavior and provides the dominant contribution to μ̄, whereas the sp contribution shows a non-monotonic (and complex) behavior as a function of the distance and of cluster size. The approaching clusters change their intrinsic magnetic moments at separations of the order of the bulk first nearest-neighbor distance dfn. For N=5–7 there is a range of separations (1dfn–3dfn) where the cluster moments are slightly enhanced.