Fermi surface topology and impurity-induced resonance state in BiS2-based superconductors

Within the two-orbital model for BiS2-based superconductors, the effect from a single nonmagnetic impurity scattering on the superconducting state is investigated in terms of the T-matrix approach. By considering three kinds of the typical Fermi surface topology which characterize the essential features of the doping dependence of the electronic structure in BiS2-based superconductors, it is found that the impurity scattering on the superconducting state with the conventional s-wave, the extended +/- s-wave, the +/- s-wave, and the d(x2-y2)-wave symmetries induces qualitatively different resonance states due to the evolution of unique nodal structures on the Fermi surface with doping. These impurity-induced resonance states can be verified directly by the scanning tunneling microscopy experiments, and therefore they are proposed as a probe of the superconducting pairing symmetry in BiS2-based superconductors. Copyright (C) EPLA, 2014.