Santos-Cottin, D. Klein, Y. Werner, Philipp Miyake, Takashi Medici, L. de Gauzzi, A. Lobo, R. P. S. M. Casula, Michele 2018-10-01 Optical conductivity measurements on a BaCoS2 single crystal unveil 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. application/pdf https://folia.unifr.ch/global/documents/307500 https://folia.unifr.ch/documents/307500/files/wer_lbo.pdf https://folia.unifr.ch/documents/307500/files/wer_lbo_sm.pdf eng info:eu-repo/semantics/altIdentifier/doi/10.1103/PhysRevMaterials.2.105001 info:eu-repo/semantics/openAccess License undefined Physical Review Materials. - 2018, vol. 2, no. 10, p. 105001 info:eu-repo/classification/udc/53 Linear behavior of the optical conductivity and incoherent charge transport in ${\mathrm{BaCoS}}_{2}$ http://purl.org/coar/resource_type/c_6501