Electronic structure of CeRhSn2 and LaRhSn2 from x-ray photoemission spectroscopy and band structure calculations

Abstract

We report on the electronic structure and magnetic properties of the Kondo lattice system CeRhSn2 and of the reference compound LaRhSn2 . The Ce 3d and 4d x-ray photoemission spectroscopy (XPS) data point to a stable configuration of the Ce 4f shell in CeRhSn2 . The ac magnetic susceptibility measurements reveal two magnetic transitions for CeRhSn 2 at temperatures T_C1 = 4 K and T_C2 = 3 K. The temperature dependences of the ac susceptibility show also broad maxima at about 17 and 15 K for CeRhSn2 and LaRhSn2 , respectively. Such features hint at spin fluctuations on Rh atoms. To get detailed insight into the electronic structure of both CeRhSn2 and LaRhSn2 we perform ab initio band structure calculations within the local (spin) density approximation (L(S)DA) and using the LSDA+U approach to account for the strong Coulomb interactions within the Ce 4f shell. The LSDA+ U approximation gives qualitatively the correct physical picture of Ce3+ in CeRhSn2 . The reliability of the theoretical results is confirmed by the comparison of the calculated XPS valence band spectra with experimental data. A Fermi surface analysis shows that there are some parallel sections of the sheets, which could generate 'nesting' instabilities. These nesting features might be responsible for the spin fluctuations suggested by the ac susceptibility measurements.