Kondo lattice excitation observed using resonant inelastic X-ray scattering at the Yb $M_5$ edge

TL;DR

This study uses resonant inelastic X-ray scattering at the Yb M5 edge to investigate Kondo lattice excitations, revealing temperature-dependent spectral renormalization linked to valence transition and electronic structure changes.

Contribution

It provides new insights into the low-energy electronic structure of Yb-based systems through direct spectroscopic observation of Kondo lattice excitations.

Findings

Observation of multiplet structure at high temperature

Spectral renormalization across the valence transition

Correlation with optical conductivity indicating mixed electronic character

Abstract

We present a study of the resonant inelastic scattering response of \ybin\ 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.