UC Irvine

The electronic band structure of Yb Rh2 Si2 is calculated in a relativistic framework including correlation corrections and magnetization of the Yb ion and compared to detailed angle-resolved photoemission spectra. The photoemission spectra for Lu Rh2 Si2 are used as reference to identify electronic bands with no f symmetry. The calculated band structure manifests a 4 f13 spin-polarized configuration leaving the unoccupied state at 1.4 eV above the Fermi energy. At the band theory level, the 4f bands are located far below the Fermi level and the anisotropic Coulomb interaction within the 4f shell spreads the multilevel into broader 4f complexes below -2.5 eV. The photoemission spectra obtained on Yb Rh2 Si2 show a clear f -multilevel splitting into j=7 2 and 5 2 excitations. The interaction of the 4 f7 2 levels close to the Fermi energy with two conduction bands shows visible hybridization gaps of 45 and 80 meV, respectively. We discuss the origin of these excitations and provide an analysis according to Anderson's single-impurity model with parameters suggested by the band-structure calculation and the photoemission spectra. Both experiment and theory indicate nearly identical Fermi surfaces for Lu Rh2 Si2 and Yb Rh2 Si2. The valency of Yb in Yb Rh2 Si2 is estimated to be close to +3. © 2007 The American Physical Society.