Minimal electronic models for superconducting BiS 2 layers

By H. Usui, Katsuhiro Suzuki, K. Kuroki. 2012

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We construct minimal electronic models for a newly discovered superconductor LaO${}_{1\ensuremath{-}x}$F${}_{x}$BiS${}_{2}$ (${T}_{c}=10.6$ K) possessing BiS${}_{2}$ layers based on a 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 a quasi-one-dimensional character with a double minimum dispersion, which gives good nesting of the Fermi surface. At around $x\ensuremath{\sim}0.5$ the topology of the Fermi surface changes, so that the density of states at the Fermi level becomes large. Possible pairing states are discussed.

Subfields: Condensed Matter Physics, Electronic, Optical and Magnetic Materials

View Paper: https://www.semanticscholar.org/paper/6fab01933298cc8497cece4b50f2d55907f7831f