Diagnosis of pairing symmetry by vortex and edge spectra in kagome superconductors

TL;DR

This study investigates the pairing symmetry in kagome superconductors AV3Sb5 by analyzing vortex and edge spectra, identifying chiral p-wave pairing as the only candidate hosting Majorana states, thus aiding in understanding their superconducting nature.

Contribution

It provides a comprehensive analysis of all proposed pairing symmetries in AV3Sb5, highlighting chiral p-wave as the unique pairing supporting Majorana bound states.

Findings

Chiral p-wave pairing hosts Majorana bound states in vortex cores.

Both p-wave and d-wave pairings exhibit chiral edge states.

f-wave pairing shows flat Andreev surface bound states.

Abstract

Layered kagome metals AV3Sb5 (A=K, Rb, Cs) exhibit diverse correlated electron phenomena. It includes charge density wave formation and superconductivity the pairing symmetry of which, however, is controversial due to contradictory experimental evidence. Through calculations based on real-space lattice models at the mean-field level, we investigate the vortex and surface spectra of all competitive pairing propensities suggested for AV3Sb5 from a weak coupling analysis of unconventional superconductivity. Chiral p-wave pairing emerges as the only option to host Majorana bound states in the vortex core. We find chiral edge states for both p-wave and d-wave pairing, along with flat Andreev surface bound states for f -wave pairing. Our results expand the fingerprint of superconducting pairing, and thus will contribute to resolving the nature of superconductivity in AV3Sb5.