Superconducting pairing symmetry in the kagome-lattice Hubbard model

The dominating superconducting pairing symmetry of the kagome-lattice Hubbard model is investigated using the determinant quantum Monte Carlo method. The superconducting instability may occur when doping the correlated insulators formed by the Hubbard interaction near the Dirac filling, and the possible superconducting state exhibits an electron-hole asymmetry. Among the pairing symmetries allowed, we demonstrate that the dominating channel is Formula Presented wave in the hole-doped case. This opens the possibility of condensation into an unconventional Formula Presented phase, which is characterized by an integer topological invariant and gapless edge states. In contrast, the Formula Presented-wave channel, which has no sign change in the pairing function, is favored by the electron doping. We further find the dominating Formula Presented wave pairing persists up to the Van Hove singularity. The results are closely related to the recent experimental observations in kagome compounds Formula Presented and provide insight into the pairing mechanism of their superconducting states.