Atomic correlations in itinerant ferromagnets: quasi-particle bands of   nickel
  We measure the band structure of nickel along various high-symmetry lines of the bulk Brillouin zone with angle-resolved photoelectron spectroscopy. The Gutzwiller theory for a nine-band Hubbard model whose tight-binding parameters are obtained from non-magnetic density-functional theory resolves most of the long-standing discrepancies between experiment and theory on nickel. Thereby we support the view of itinerant ferromagnetism as induced by atomic correlations. 
J. Buenemann, F. Gebhard, T. Ohm, R. Umstaetter, S. Weiser, W. Weber,   R. Claessen, D. Ehm, A. Harasawa, A. Kakizaki, A. Ki...