Symmetry-Enforced Pair-Density Wave and Chiral Interband Superconductivity in Strongly Correlated Kagome Systems

Abstract

The pair-density wave (PDW) state, characterized by Cooper pairing at finite momentum, is a long-sought superconducting phase whose possible realization in Kagome metals is particularly intriguing in the strongly correlated regime. We investigate superconductivity in the extended $t$-$J$ model on the Kagome lattice and show that the symmetry-enforced sublattice structure of the Bloch wavefunctions gives rise to a rich landscape of unconventional pairing states. When the chemical potential is tuned to a sublattice-pure ($p$-type) van Hove singularity (vHS), a PDW state inevitably emerges. Near the $m'$-type vHS, which features opposite mirror eigenvalues to the conventional $m$-type vHS, intraband chiral, uniform, and nematic pairing states compete. When further-neighbor hoppings drive the $p$- and $m'$-type vHSs towards near degeneracy, phase frustration in the interband pairing channel stabilizes a chiral interband state. Our results reveal the previously overlooked $m'$-type vHS as a distinct route to unconventional superconductivity rooted in electronic correlations and mirror-symmetry-constrained Bloch wavefunctions.