BiS2 - based superconductivity in F-substituted NdOBiS2

Source: arXiv

ABSTRACT 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.
    Physical review. B, Condensed matter 07/2012; 86(22). DOI:10.1103/PhysRevB.86.220501 · 3.66 Impact Factor
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    ABSTRACT: We report the electrical resistivity measurements under pressure for the recently discovered BiS2-based layered superconductors Bi4O4S3 and La(O,F)BiS2. In Bi4O4S3, the transition temperature Tc decreases monotonically without a distinct change in the metallic behavior in the normal state. In La(O,F)BiS2, on the other hand, Tc initially increases with increasing pressure and then decreases above ? 1 GPa. The semiconducting behavior in the normal state is suppressed markedly and monotonically, whereas the evolution of Tc is nonlinear. The strong suppression of the semiconducting behavior without doping in La(O,F)BiS2 suggests that the Fermi surface is located in the vicinity of some instability. In the present study, we elucidate that the superconductivity in the BiS2 layer favors the Fermi surface at the boundary between the semiconducting and metallic behaviors.
    Journal of the Physical Society of Japan 07/2012; 81(10). DOI:10.1143/JPSJ.81.103702 · 1.59 Impact Factor
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    ABSTRACT: Starting from a two-orbital model and based on the random phase approximation, spin excitations in the superconducting state of the newly discovered BiS$_2$ superconductors with three possible pairing symmetries are studied theoretically. We show that spin response is uniquely determined by the pairing symmetry. Possible spin resonance excitations might occur for the d-wave symmetry at an incommensurate momentum about $(0.7\pi,0.7\pi)$. For the p-wave symmetry the transverse spin excitation near $(0,0)$ is enhanced. For the s-wave pairing symmetry there is no spin resonance signature. These distinct features may be used for probing or determining the pairing symmetry in this newly discovered compound.
    Journal of Superconductivity and Novel Magnetism 08/2012; 26(8). DOI:10.1007/s10948-012-2073-4 · 0.91 Impact Factor
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