Abstract
We study the electronic structure of the skutterudite , which is known to exhibit a charge density wave (CDW) transition, at temperature K, coupled to a metal-to-metal transition. We use temperature dependent hard x-ray photoemission spectroscopy (HAXPES) and x-ray absorption spectroscopy (XAS) to investigate the occupied and unoccupied electronic states of . The Co and Sn core level spectra show small but finite shifts in binding energy positions across while Ce core level spectra do not show any change across the transition. The Ce -edge XAS spectrum compared with calculations indicate a typical trivalent ionic spectral shape, ruling out Kondo screening in . In contrast, the Co -edge XAS spectrum compared with a calculated spectrum shows evidence for hybridization with neighboring Sn atoms in a trigonal prismatic co-ordination. Temperature dependent XAS across the Co -edge shows a small shift across , consistent with HAXPES results. Detailed XAS measurements as a function of temperature show that the spectral shifts occur with a hysteresis across , indicative of a first-order transition. Valence band spectra show a normal Fermi edge above and below . The Co states are observed at a binding energy of eV while the Ce states occur as a weak feature within 0.5 eV of the Fermi level. The results suggest an unusual CDW transition coupled to a metal-to-metal transition in .
- Received 25 June 2018
- Revised 21 November 2018
DOI:https://doi.org/10.1103/PhysRevB.98.235136
©2018 American Physical Society