Fermi-Surface Topology and Pairing Symmetry in BiS${}_2$-Based Layered Superconductors

Abstract

In order to clarify superconducting properties of BiS${}_2$-based layered superconductors LaO${}_{1-x}$F${}_x$BiS${}_2$, we evaluate the superconducting transition temperature $T_{\mathrm{c}}$ and analyze the gap function in a weak-coupling limit on the basis of the two-dimensional two-orbital Hubbard model. It is found that $T_{\mathrm{c}}$ becomes maximum at $x=0.6$ in the present calculations. For $x<0.45$, we obtain the $d$-wave gap of which line nodes do not cross the pocket-like Fermi-surface curves with the centers at X and Y points. On the other hand, for $x>0.45$, the extended $s$-wave gap is found for a couple of large Fermi-surface curves with the centers at M and X points. The variation of the Fermi-surface topology plays a key role for the gap symmetry in BiS${}_2$-based superconductors.

8 pages, 8 figures. To appear in J. Magn. Magn. Mater. (Proceedings for ICM2015)

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Cited by in corpus (9)

• Material Development and Physical Properties of BiS2-Based Layered Compounds
• Direct evidence of hidden local spin polarization in a centrosymmetric superconductor LaO${}_{0.55}$F${}_{0.45}$BiS${}_2$
• Unconventional superconductivity in the BiS${}_2$-based layered superconductor NdO${}_{0.71}$F${}_{0.29}$BiS${}_2$
• Conventional s-wave superconductivity in BiS2-based NdO0.71F0.29BiS2 revealed by thermal transport measurements
• Superconducting gap symmetry of the BiS${}_2$-based superconductor LaO${}_{0.5}$F${}_{0.5}$BiSSe elucidated through specific heat measurement
• Charge/quadrupole fluctuations and gap anisotropy in BiS${}_2$-based superconductors
• Impurity Effects in Nodal Extended $s$- and Nodeless $d$-Wave Superconductors: Gap Symmetry of BiS${}_2$-Based Layered Superconductors
• Extremely high upper critical field in BiCh${}_2$-based (Ch: S and Se) layered superconductor LaO${}_{0.5}$F${}_{0.5}$BiS${}_{2-x}$Se${}_x$ ($x$ = 0.22 and 0.69)
• Particular type of gap in the spectrum of multiband superconductors