Temperature-dependent valence-band photoemission study of UNiSn

The electronic structure of UNiSn has been investigated using photoemission spectroscopy (PES). The U 5f partial spectral weight (PSW) exhibits a broad peak centered at approximate to0.3 eV below E-F. The Ni 3d PSW shows the main peak well below E-F and a very low density of states (DOS) at E-F. The h nu dependence of the valence-band spectrum reveals a dominant U 5f electron character for the states near the Fermi level E-F, with a small contribution from the U 6d, Ni 3d, and Sn sp states. Comparison of the measured PES spectra to the LSDA+ U band structure calculation indicates the importance of the on-site Coulomb interaction between U 5f electrons in UNiSn. The high-resolution photoemission spectrum of UNiSn is described well by a V-shaped metallic DOS near E-F, suggesting a finite but reduced DOS at E-F. A possible origin for the reduced DOS at E-F might be the hybridization of the U 5f states to the Ni 3d states that have a very low DOS at E-F. T-dependent high-resolution PES for UNiSn reveals a finite DOS at E-F even above T-N.