Electronic structure of semiconductingCeFe4P12: Strong hybridization and relevance of single-impurity Anderson model

Abstract

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

Ce 4f electronic states of CeO1−xFxBiS2 studied by sof

“…The observed on-resonant spectra for CeO 0.3 F 0.7 BiS 2 resemble the one for semiconducting skutterudite CeFe 4 P 12 [46], although the binding energy of the main peak for CeFe 4 P 12 is smaller (at 0.7 eV) and the width of the flat portion in the higher biding energy region is narrower (from 1.5 to 3 eV). The width of the main peak ( E 4f = 0.88 eV) is slightly broader than the ones for CeO 0.3 F 0.7 BiS 2 .…”

Collapse of the Gd3+ ESR fine structure throughout the coherent temperature of the Gd-doped Kondo Semiconductor CeFeVenegas1, Garcia2, García3 et al. 2016Phys. Rev. B80100View full textAdd to dashboardCite

“…However, in skutterudites, there is also the intriguing possibility that the coupling between the electronic state and the low energy vibrations of the lattice may lead to FV and Kondo-like phenomena. In 4 12 CeFe P , the picture obtained from spectroscopic experiments [1,22], indicates a large f-ce hybridization strength. Below * T , lattice vibrations cooperate coherently with the electronic insulating state, favoring the opening of the hybridization gap.…”

“…Concerning 4 12 CeFe P , its semiconducting properties at low-T were considered anomalous when compared to other isostructural members of this class of compounds, most of which are metallic and magnetic [22]. The resistivity varies over six orders of magnitude between 50 K and 300 K, but the data can only be fitted to an activated conduction process over a limited temperature range.…”

“…Recent studies of Ce and Sm compounds in this class of materials led to a renewed interest in this old hybridization gap (pseudogap) problem [1,2] and also to new, exotic types of Kondo effects [26]. Photoemission Spectroscopy on single crystals of 4 12 CeFe P [1,22] showed a strong mixed-valence behavior of Ce ions, with a three-peak structure for the 4f - which is near the trivalent case as the nominal valence (value of 3.14). In addition, the anomaly observed in the lattice parameter [3,27] and results from band structure calculations [23] are also compatible with an intermediate-valence for the Ce ions.…”

“…Spectroscopic experiments [1,22] In this Supplemental Materials we show that electron-lattice coupling leads to a low temperature paramagnetic insulator and a high temperature metal at half filling. To illustrate the mechanism we consider a simple one dimensional geometry although similar results can be obtained in more dimensions.…”