Crossover between electron-electron and electron-phonon mediated pairing on the kagome lattice

Abstract

We study electron-electron and electron-phonon mediated pairing in the Holstein extended Hub-bard model on the Kagome lattice near the van Hove fillings, and investigate their combined effectson electron pairing states. We find that their combination can promote exotic pairings in a crossoverregion, where the filling is close to a van Hove singularity. In particular, at the p-type van Hove fill-ing the E1u (p-wave) and B2u (fy3−3yx2 -wave) pairings become leading, and at the m-type van Hovefilling the E1u and A2g (i-wave) pairings get promoted. Moreover, we show that the electron-phononinteraction acquires a significant momentum dependence, due to the sublattice texture of the Fermisurfaces, which can promote non s-wave pairing. We present a detailed analysis of these pairingpropensities and discuss implications for the vanadium-based kagome superconductors AV3Sb.