Spin-dependent local density of empty electronic states in FeNi3

The electronic structure of the magnetic compound FeNi3 is investigated by spin-resolved soft-x-ray appearance potential spectroscopy. The spectra which reflect the local densities of empty states on the Fe and Ni sites in this compound are compared with results for the pure elements. A detailed description and interpretation of the experimental spectra is achieved by a comparison with theoretical spectra. They were calculated, within a single-particle picture, from the underlying electronic structure including a proper treatment of transition matrix elements. The experimentally observed energetic shifts and spin-asymmetry changes between the pure elements and the compound are understood as a consequence of changes in the spin-dependent local densities of states and in the core-level binding energies. In particular, this allowed us to determine the changes in the binding energies for the 2p(3/2) states of Fe and Ni in the compound with respect to the pure elements.