BiS2 - based superconductivity in F-substituted NdOBiS2

Source: arXiv


We have successfully synthesized a new BiS2-based superconductor NdOBiS2 with
F-doping. This compound is composed of superconducting BiS2 layers and blocking
NdO layers, which indicates that the BiS2 layer is the one of the common
superconducting layers like the CuO2 layer of cuprates or Fe-As layer of
Fe-based superconductors. We can obtain NdO1-xFxBiS2 with bulk
superconductivity by a solid-state reaction under ambient pressure. Therefore,
NdO1-xFxBiS2 should be the suitable material to elucidate the mechanism of
superconductivity in the BiS2-layer.

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Available from: Saleem J Denholme, Nov 25, 2014
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    ABSTRACT: We construct minimal electronic models for a newly discovered superconductor LaO$_{1-x}$F$_x$BiS$_2$ ($T_c=$ 10.6K) possessing BiS$_2$ layers based on first principles band calculation. First, we obtain a model consisting of two Bi $6p$ and two S $3p$ orbitals, which give nearly electron-hole symmetric bands. Further focusing on the bands that intersect the Fermi level, we obtain a model with two $p$ orbitals. The two bands (per BiS$_2$ layer) have quasi-one-dimensional character with a double minimum dispersion, which gives good nesting of the Fermi surface. At around $x\sim 0.5$ the topology of the Fermi surface changes, so that the density of states at the Fermi level becomes large. Possible pairing states are discussed.
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