Spin-Orbit Coupling in Ferromagnetic Nickel

We use the Gutzwiller variational theory to investigate the electronic and magnetic properties of fcc nickel. Our particular focus is on the effects of the spin-orbit coupling. Unlike standard relativistic band-structure theories, we reproduce the experimental magnetic-moment direction and we explain the change of the Fermi-surface topology that occurs when the magnetic-moment direction is rotated by an external magnetic field. The Fermi surface in our calculation deviates from early de Haas-van Alphen results. We attribute these discrepancies to an incorrect interpretation of the raw de Haas-van Alphen data.