Quantitative investigation of the 4$f$ occupation in the quasikagome Kondo lattice CeRh$_{1-x}$Pd$_x$Sn

TL;DR

This study uses photoelectron spectroscopy to analyze how substituting Rh with Pd in CeRhSn affects the 4$f$ electron occupation, revealing a smooth decrease in 4$f^0$ contribution and changes in hybridization and binding energy.

Contribution

It provides a detailed quantitative analysis of 4$f$ occupation changes in CeRh$_{1-x}$Pd$_x$Sn using HAXPES, linking electronic structure modifications to chemical substitution.

Findings

4$f^0$ contribution decreases smoothly with Pd substitution

Effective 4$f$ binding energy increases with Pd content

Pd 4$d$ states are farther from Ce 4$f$ states than Rh 4$d$ states

Abstract

CeRhSn with the Ce atoms forming a quasikagome lattice in the hexagonal plane has recently been discussed in the context of quantum criticality driven by magnetic frustration. Furthermore, it has been reported that the successive substitution of Rh by Pd leads to magnetic order. Here we have investigated the change of the 4$f$ occupation in the substitution series CeRh$_{1-x}$Pd$_x$Sn for for $x$ = 0, 0.1, 0.3, 0.5, 0.75 by means of photoelectron spectroscopy with hard x-rays (HAXPES). The quantitative analysis of the core level spectra with a combined full multiplet and configuration interaction analysis shows a smooth decrease of the 4$f^0$ contribution with rising $x$ due to an increase of the effective 4$f$ binding energy $\varepsilon_{4f}$ and the reduction of the effective hybridization $V_\text{eff}$. We further compare valence band data with the calculated partial density of states and find that the Pd 4$d$ states are about 1eV further away from the Ce 4$f$ states at the Fermi energy than the Rh 4$d$ states. In fact, the effective binding energy $\varepsilon_{4f}$ of the 4$f$ states in the configuration interaction analysis of the core level spectra decreases by the same amount.