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.

We present a soft x-ray angle-resolved photoemission spectroscopy (SX-ARPES) study of the stoichiometric pnictide superconductor LaRu(2)P(2). The observed electronic structure is in good agreement with density functional theory (DFT) calculations. However, it is significantly different from its counterpart in high-temperature superconducting Fe pnictides. In particular, the bandwidth renormalization present in the Fe pnictides (~2-3) is negligible in LaRu(2)P(2) even though the mass enhancement is similar in both systems. Our results suggest that the superconductivity in LaRu(2) P(2) has a different origin with respect to the iron pnictides. Finally, we demonstrate that the increased probing depth of SX-ARPES, compared to the widely used ultraviolet ARPES, is essential in determining the bulk electronic structure in the experiment.

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In VeryLEED regime (below 30 eV) the spectra of electron reflection on the surfaces of crystals are dominated by the elastic effects of bulk E(k) above the vacuum level. This is revealed when the reflected intensity is found by matching on the surface the wave-function in vacuum (plane waves) and in the solid (Bloch waves). Following reflectivity features versus energy and incidence angle, one can extract accurate and explicit information on upper E(k): the energies of extremes of bands along any Brillouin zone direction, and even whole bands along symmetry lines. This is illustrated with a profusion of experimental examples. The theoretical background and the experimental technique are surveyed. Capabilities of VeryLEED to generate the upper bands for PES (IPES) are outlined.