Temperature-dependent electronic structure of large T_K Ce compounds

Very high Kondo temperature (T_K) Ce compounds, with large hybridization of Ce 4f states resulting in mixing of 4f crystal-electric-field (CEF) states, are expected to exhibit some qualitatively different temperature-dependent spectroscopic properties compared to low T_K systems with well defined more localized 4f CEF states. Recently, large T-dependent energy shifts of ~80 meV have been measured in the unoccupied states of CePd₃ (T_K~600K) using resonant inelastic scattering and compared to dynamical mean field theory (DMFT) calculations [1] . Here, we probe, using angle-resolved photoemission, the T-dependent electronic structure of occupied of states of the quasi-kagome Kondo lattice system of CeRhSn with a similar large T_K. We observed clear 50 meV energy shifts of strongly f-hybridized hole-bands at E_F and a non-f band at -0.13 eV below, which provide an additional quantitative test for refinement of DMFT calculations that have previously provided good agreement with T-dependent optical conductivity of CeRhSn [2]. We discuss the underlying f-electron physics issues raised by these results in comparison to the experimental and predicted T-dependent crossover behavior of low T_K materials such as CeCoIn₅ [3].

[1] M.C. Rahn, et al., Nat. Commun. 13, 6129 (2022).

[2] T.U. Böhm, et al., Phys. Rev. B 110, l121107 (2024).

[3] S. Jang, et al., PNAS 117, 23467 (2020).