UC Irvine

The k-resolved single particle excitations, as determined by angle-resolved photoemission spectroscopy (ARPES), are compared and contrasted for, LaRu2Si2, CeRu2Si2, ThRu2Si2, and URu2Si2, isostructural layered compounds with differing nominal f-occupations of f0, f1, f0, and f2, respectively. ARPES measurements include 4d and 5d-edge resonant photoemission to distinguish f-character and Fermi-energy intensity mapping of Fermi surface contours. Comparison to RLAPW band structure calculations shows very good agreement of the d-band structure away from EF. Discrepancies in the near EF region highlight k-dependent effects of f-correlation and f-d hybridization. Approximately equal dimensions of Fermi contours for X=(La, Ce) suggest the exclusion of 4f electrons from the CeRu2Si2 Fermi surface at temperatures far above the Kondo temperature. High-resolution spectra for X=(Ce, U) allow comparison of f-d mixing to predictions of the Anderson lattice model. Published by Elsevier Science B.V.