Electronic structure of CeRhX (X = Sn,In)

Electronic structure of the compounds CeRhIn and CeRhSn have been studied by the X-ray photoemission spectroscopy (XPS) and ab initio band structure calculations. CeRhSn shows the non-Fermi liquid characteristics at low temperatures, while CeRhIn exhibits a Fermi-liquid ground state. At ambient temperature the XPS data reveal an intermediate valence state of Ce ions in both systems. The Ce core-level XPS spectra are very similar and indicate the strong coupling of the Ce 4f and the conduction band states (Δ ≈ 100 meV). The valence band spectra we interpret with the help of ab initio calculations as well as using the results for the reference compounds LaRhIn and LaRhSn. The comparative analysis of the theoretical band structures and charge density plots reveal the changes in chemical bonding and the hybridization between the Ce 4f and the other valence states introduced by the replacement of In by Sn atoms. The more covalent character of the chemical bonding in the stannides is in line with the smaller thermal expansion. Finally, for CeRhIn we found a typical temperature dependence of the crystal lattice, while CeRhSn shows distinct anomaly at about 120 K, presumably related to the change in planar Ce–Rh bonds.