Nature of Unconventional Pairing in the Kagome Superconductors AV3Sb5 (A = K, Rb, Cs)

The recent discovery of AV(3)Sb(5) (A = K, Rb, Cs) has uncovered an intriguing arena for exotic Fermi surface instabilities in a kagome metal. Among them, superconductivity is found in the vicinity of multiple van Hove singularities, exhibiting indications of unconventional pairing. We show that the sublattice interference mechanism is central to understanding the formation of superconductivity in a kagome metal. Starting from an appropriately chosen minimal tight-binding model with multiple van Hove singularities close to the Fermi level for AV(3)Sb(5), we provide a random phase approximation analysis of superconducting instabilities. Nonlocal Coulomb repulsion, the sublattice profile of the van Hove bands, and the interaction strength turn out to be the crucial parameters to determine the preferred pairing symmetry. Implications for potentially topological surface states are discussed, along with a proposal for additional measurements to pin down the nature of superconductivity in AV(3)Sb(5).

Automated summary

The recent discovery of AV(3)Sb(5) has revealed an intriguing arena for exotic Fermi surface instabilities in a kagome metal, with superconductivity near multiple van Hove singularities showing indications of unconventional pairing. The sublattice interference mechanism is crucial in understanding the formation of superconductivity in a kagome metal, with nonlocal Coulomb repulsion, the sublattice profile of the van Hove bands, and the interaction strength being crucial parameters determining the preferred pairing symmetry. Implications for potentially topological surface states are discussed, along with a proposal for additional measurements to determine the nature of superconductivity in AV(3)Sb(5).