g-wave pairing in BiS2 superconductors

Recent angle-resolved photoemission spectroscopy (ARPES) experiments have suggested that BiS2-based superconductors are at very low electron doping. Using random phase approximation (RPA) and functional renormalization group (FRG) methods, we find that g-wave pairing symmetry belonging to the A(2g) irreducible representation is dominant at electron doping x < 0.25. The pairing symmetry is determined by inter-pocket nesting and orbital characters on the Fermi surfaces and is robust in a two-orbital model including both Hund's coupling J, and Hubbard-like Coulomb interactions U and U' with relatively small J (J <= 0.2U). With the increasing electron doping, the g-wave state competes with both the s-wave A(1g) and d-wave B-2g states and no pairing symmetry emerges dominantly. Copyright (C) EPLA, 2014