Band structure and Fermi surface of UPd3studied by soft x-ray angle-resolved photoemission spectroscopy

Abstract

Soft x-ray angle-resolved photoemission experiments have been performed to investigate the band structure and Fermi surface of UPd${}_{3}$. We have observed three U 5$f$ derived bands whose bandwidths are very narrow. Two of these bands appear around 0.8 eV and are slightly separated by about 0.2 eV. The presence of two bands at nearly the same energy might be due to the presence of the two inequivalent U sites. The other U 5$f$ band appears around 1.8 eV. The energy separation between this band and the two nearly degenerate bands agrees with the 5${f}^{1}$-final-state multiplet model. In the vicinity of Fermi level, several highly dispersive bands, which form a holelike Fermi surface centered at the $\ensuremath{\Gamma}$ point and an electronlike Fermi surface at the K point, were observed. These dispersive valence bands are qualitatively explained by a band structure calculation that assumes a localized 5${f}^{2}$ configuration. All these experimental observations are consistent with the localized U 5$f$ nature.