Electronic structure of semiconducting CeFe$_4$P$_{12}$: Strong hybridization and relevance of single-impurity Anderson model

TL;DR

This study uses spectroscopic techniques and theoretical models to analyze the electronic structure of CeFe4P12, revealing strong hybridization effects and the relevance of the single-impurity Anderson model in describing its semiconducting behavior.

Contribution

It demonstrates the importance of the single-impurity Anderson model in explaining the electronic structure and hybridization effects in CeFe4P12, a Kondo semiconducting material.

Findings

Absence of Kondo resonance at Fermi level in Ce 4f DOS

Strong hybridization between conduction electrons and Ce 4f states

Confirmation of mixed valence behavior through SIAM analysis

Abstract

Semiconducting skutterudite CeFe$_4$P$_{12}$ is investigated by synchrotron x-ray photoemission spectroscopy (PES) and x-ray absorption spectroscopy (XAS). Ce 3$d$ core-level PES and 3$d-4f$ XAS, in combination with single impurity Anderson model (SIAM) calculations, confirm features due to $f^0$, $f^1$ and $f^2$ configurations. The Ce 4$f$ density of states (DOS) indicates absence of a Kondo resonance at Fermi level, but can still be explained by SIAM with a small gap in non-$f$ DOS. While Ce 4$f$ partial DOS from band structure calculations are also consistent with the main Ce 4$f$ DOS, the importance of SIAM for core and valence spectra indicates Kondo semiconducting mixed valence for CeFe$_4$P$_{12}$, derived from strong hybridization between non-$f$ conduction and Ce 4$f$ DOS.