Local Electronic Structures Around a Nonmagnetic Impurity in $$\hbox {BiS}_2$$ BiS 2 -Based Superconductors

Abstract

In a superconductor, the crucial requirement is to confirm the pairing symmetry of the superconducting (SC) state, which could help to reveal the underlying SC mechanism. In this paper, we use the local electronic structure around a single nonmagnetic impurity to probe the pairing symmetry in recently discovered $$\hbox {BiS}_{2}$$ -based superconductors, where no general consensus on the pairing symmetry has been reached so far. We find that the effect from a single nonmagnetic impurity scattering on the SC-state with the conventional s-wave, the extended s-wave, and the $$d_{x^2 -y^2}$$ -wave symmetries may induce qualitatively different resonance states. Since impurity-induced resonance states can be verified directly by scanning tunneling microscopy experiments, they are proposed as a test of the SC pairing symmetry in $$\hbox {BiS}_{2}$$ -based superconductors.