Tri-component-pairing chiral superconductivity on the honeycomb lattice with mixed s- and d-wave symmetries

Abstract: In this work, we investigate chiral topological superconductors on a two-dimensional honeycomb lattice with coexisting d_1- (i.e., x^2-y^2), d_2- (i.e., xy), and s-wave pairing symmetries. Using a Ginzburg-Landau free energy analysis, the pairing gap function is shown to exhibit a tri-component form s + d_1 exp(i phi_1) + d_2 exp(i phi_2), where phi_1 and phi_2 are phase differences between the d- and s-wave pairing components, which spontaneously breaks both time reversal and C_6 rotational symmetries. Chern numbers of the energy bands are calculated to be nonzero, demonstrating the topologically nontrivial nature of the system. The anomalous AC Hall conductivity is also computed, which is not invariant under C_6 rotations, reflecting the anisotropic nature of the pairing gap function.