Quantitative study of valence and configuration interaction parameters of the Kondo semiconductors CeM2Al10 (M = Ru, Os and Fe) by means of bulk-sensitive hard x-ray photoelectron spectroscopy

TL;DR

This study uses bulk-sensitive hard x-ray photoelectron spectroscopy to quantitatively analyze valence and configuration interaction parameters in CeM2Al10 Kondo semiconductors, revealing differences in exchange interactions and Kondo screening.

Contribution

It provides the first quantitative determination of 4f^n occupancy and configuration interaction parameters in CeM2Al10 compounds using HAXPES combined with multiplet calculations.

Findings

CeOs2Al10 shows stronger exchange interaction than CeRu2Al10.

CeFe2Al10 exhibits a significant increase in hybridization strength.

All compounds are in the strong exchange interaction regime, with coexistence of Kondo screening and magnetic order.

Abstract

The occupancy of the 4f^n contributions in the Kondo semiconductors CeM2Al10(M = Ru, Os and Fe) has been quantitatively determined by means of bulk-sensitive hard x-ray photoelectron spectroscopy (HAXPES) on the Ce 3d core levels. Combining a configuration interaction scheme with full multiplet calculations allowed to accurately describe the HAXPES data despite the presence of strong plasmon excitations in the spectra. The configuration interaction parameters obtained from this analysis -- in particular the hybridization strength V_eff and the effective f binding energy Delta_f -- indicate a slightly stronger exchange interaction in CeOs2Al10 compared to CeRu2Al10, and a significant increase in CeFe2Al10. This verifies the coexistence of a substantial amount of Kondo screening with magnetic order and places the entire CeM2Al10 family in the region of strong exchange interactions.