Angle-resolved photoelectron spectroscopy (ARPES) was used to study the Fermi surface of the heavy-fermion system ${\mathrm{YbRh}}_2{\mathrm{Si}}_2$ at a temperature of about 10 K, i.e., a factor of 2 below the Kondo energy scale. We observed sharp structures with a well-defined topology, which were analyzed by comparing with results of band-structure calculations based on the local-density approximation (LDA). The observed bulk Fermi surface presents strong similarities with that expected for a trivalent Yb state, but is slightly larger, has a strong $\mathrm{Yb}\mathrm{\text{−}}4f$ character, and deviates from the LDA results by a larger region without states around the $\overline{\Gamma }$ point. These properties are qualitatively explained in the framework of a simple $f\mathrm{\text{−}}d$ hybridization model. Our analysis highlights the importance of taking into account surface states and doing an appropriate projection along ${\mathit{k}}_z$ when comparing ARPES data with results from theoretical calculations.

• Received 9 June 2011

DOI:https://doi.org/10.1103/PhysRevLett.107.267601