Studies of Electronic Structure across a Quantum Phase Transition in CeRhSb$_{1-x}$Sn$_x$

TL;DR

This study investigates the electronic structure changes in CeRhSb$_{1-x}$Sn$_x$ across a quantum phase transition from a Kondo insulator to a non-Fermi liquid, combining photoelectron spectroscopy and band structure calculations.

Contribution

It provides experimental photoelectron spectra and theoretical band structure calculations revealing how Sn substitution affects the electronic states and Fermi surface topology in CeRhSb$_{1-x}$Sn$_x$.

Findings

Spectral intensity at the Fermi level increases with Sn content.

Band structure shifts indicate hole doping and multiple Lifshitz transitions.

Depletion of density of states at the Fermi level in CeRhSb is observed.

Abstract

We study an electronic structure of CeRhSb$_{1-x}$Sn$_x$ system, which displays quantum critical transition from a Kondo insulator to a non-Fermi liquid at $x=0.13$. We provide ultraviolet photoelectron spectra of valence band obtained at 12.5 K. Acoherent peak at the Fermi level is not present in the data, but a signal related to 4f$^1$$_{7/2}$ final state is detected. Spectral intensity at the Fermi edge has a general tendency to grow with Sn content. Theoretical calculations of band structure are realized with full-potential local-orbital minimum-basis code using scalar relativistic and full relativistic approach. The calculations reveal a depletion of density of states at the Fermi level for CeRhSb. This gap is shifted above the Fermi energy with increasing Sn content and thus a rise of density of states at the Fermi level is reflected in the calculations. It agrees with metallic properties of compounds with larger $x$. The calculations also yield another important effects of Sn substitution. Band structure is displaced in a direction corresponding to hole doping, although with deviations from a rigid band shift scenario. Lifshitz transitions modify a topology of the Fermi surface a few times and a number of bands crossing the Fermi level increases.