Temperature Evolution of the Kondo Lattice CeCoIn5

Monday, September 11, 2017 - 2:30pm

The temperature-dependence of f-d hybridized band dispersions and Fermi-energy f spectral weight in the Kondo lattice system CeCoIn5 is investigated using f-resonant angle-resolved photoemission (ARPES) with sufficient detail to allow direct comparison to first principles dynamical mean field theory (DFT+DMFT) calculations containing full realism of crystalline electric field (CEF) states.  The low T ARPES results [1], for two orthogonal (001) and (100) cleaved surfaces, show the counterintuitive result that features peculiar to the localized f-electron 3D Fermi surface found in DFT calculations nonetheless display clear itinerant f-electron participation, consistent with the low energy scale description of DFT+DMFT.  Also the ARPES T dependence of three different f-d hybridization scenarios, with additional microscopic insight provided by DMFT, reveal f participation in the Fermi surface at temperatures much higher than the lattice coherence temperature, T* ≈ 45 K, commonly believed to be the onset for such behavior. The observation of a T-dependent CEF degeneracy crossover in the DMFT theory, below T*, is specifically highlighted. [1] S. Y. Jang et al., arXiv:1704.08247 (2017).

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