Impurity Effect as a Probe of the Pairing Symmetry in BiS2-Based Superconductors

Abstract

The impurity effects are studied for the BiS_{2}- layered superconductors based on a two orbital model with the Bogoliubov-de-Gennes technique. The superconducting critical temperature (T_{c}) as a function of the mpurity concentration is calculated. Significant reduction of T_{c} is found for spin singlet nearest-neighboring paring d-wave state and the spin triplet next-nearest-neighboring (NNN) paring p-wave state, while no depression of T_{c} for isotropic s-wave state. The single impurity effects for various paring states are also explored. The impurity resonance peak in the local density of states spectrum is found only for the d-wave state. For the spin triplet NNN paring p-wave state, two in-gap peaks occur in the case of positive impurity potential; and a single in-gap peak is found for the negative impurity potential, which shifts towards to lower energy with decreasing the potential strength. These results can be used to detect the paring symmetry of the BiS_{2}- based superconductors.