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

Abstract

The occupancy of the 4f^n contributions in the Kondo semiconductors\nCeM2Al10(M = Ru, Os and Fe) has been quantitatively determined by means of\nbulk-sensitive hard x-ray photoelectron spectroscopy (HAXPES) on the Ce 3d core\nlevels. Combining a configuration interaction scheme with full multiplet\ncalculations allowed to accurately describe the HAXPES data despite the\npresence of strong plasmon excitations in the spectra. The configuration\ninteraction parameters obtained from this analysis -- in particular the\nhybridization strength V_eff and the effective f binding energy Delta_f --\nindicate a slightly stronger exchange interaction in CeOs2Al10 compared to\nCeRu2Al10, and a significant increase in CeFe2Al10. This verifies the\ncoexistence of a substantial amount of Kondo screening with magnetic order and\nplaces the entire CeM2Al10 family in the region of strong exchange\ninteractions.\n