We present a study of the resonant inelastic scattering response of ${\mathrm{YbInCu}}_4$ excited at the tender Yb $M_5$ x-ray edge. In the high-temperature, paramagnetic phase, we observe a multiplet structure which can be understood at an ionic level. Upon cooling through the valence transition at $T_v\sim 40$ K, we observe a strong renormalization of the low-energy spectra, indicating a sensitivity to the formation of an intermediate valence phase at low temperatures. Similar spectrum renormalization has been observed in the optical conductivity, which suggests that the low-energy electronic structure possesses both mixed conduction and localized character.

• Received 16 November 2017

DOI:https://doi.org/10.1103/PhysRevB.98.075158