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arXiv · 1712.01539

Linear behavior of the optical conductivity and incoherent charge transport in BaCoS2

D. Santos-Cottin·Y. Klein·Ph. Werner·T. Miyake·L. de' Medici·A. Gauzzi·R. P. S. M. Lobo·M. Casula
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Abstract

Optical conductivity measurements on a BaCoS2 single crystal show an unusual linear behavior over a broad spectral range. In the paramagnetic phase above 300 K, the spectrum shows no gap, which contradicts the previously proposed scenario of a charge-transfer Mott insulator. Ab initio dynamical mean field theory calculations including a retarded Hubbard interaction explain the data in terms of an incipient opening of a Co(3d)-S(3p) charge-transfer gap concomitant to incoherent charge transport driven by electronic correlations. These results point to a non-Fermi liquid scenario with Hund's metal properties in the paramagnetic state, which arises from an incipient Mott phase destabilized by low-energy charge fluctuations across the vanishing 3d-3p charge-transfer gap.

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D. Santos-Cottin, Y. Klein, Ph. Werner, T. Miyake, L. de' Medici, A. Gauzzi, R. P. S. M. Lobo, M. Casula. 2017-12-05. Linear behavior of the optical conductivity and incoherent charge transport in BaCoS2. https://doi.org/10.1103/physrevmaterials.2.105001

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