Electronic structure ofThRu2Si2studied by angle-resolved photoelectron spectroscopy: Elucidating the contribution of U5fstates inURu2Si2

Abstract

The electronic structure of ${\mathrm{ThRu}}_{2}{\mathrm{Si}}_{2}$ was studied using angle-resolved photoelectron spectroscopy (ARPES) with incident photon energies of $h\ensuremath{\nu}=655$--745 eV. Detailed band structure and the three-dimensional shapes of Fermi surfaces were derived experimentally, and their characteristic features were mostly explained by means of band-structure calculations based on density-functional theory. Comparison of the experimental ARPES spectra of ${\mathrm{ThRu}}_{2}{\mathrm{Si}}_{2}$ with those of ${\mathrm{URu}}_{2}{\mathrm{Si}}_{2}$ shows that they have considerably different spectral profiles, particularly in the energy range of $1\phantom{\rule{4pt}{0ex}}\mathrm{eV}$ from the Fermi level, suggesting that $\mathrm{U}\phantom{\rule{4pt}{0ex}}5f$ states are substantially hybridized in these bands. The relationship between the ARPES spectra of ${\mathrm{URu}}_{2}{\mathrm{Si}}_{2}$ and ${\mathrm{ThRu}}_{2}{\mathrm{Si}}_{2}$ is very different from the one between the ARPES spectra of ${\mathrm{CeRu}}_{2}{\mathrm{Si}}_{2}$ and ${\mathrm{LaRu}}_{2}{\mathrm{Si}}_{2}$, where the intrinsic difference in their spectra is limited only in the very vicinity of the Fermi energy. The present result suggests that the $\mathrm{U}\phantom{\rule{4pt}{0ex}}5f$ electrons in ${\mathrm{URu}}_{2}{\mathrm{Si}}_{2}$ have strong hybridization with ligand states and have an essentially itinerant character.