Fractional $1/3$ quantum vortices in chiral $d+id$ kagome superconductors

TL;DR

This paper theoretically investigates fractional $1/3$ quantum vortices in chiral $d+id$ kagome superconductors, revealing their unique flux and sublattice signatures, relevant to recent experimental observations.

Contribution

It introduces a microscopic model showing the existence of fractional vortices with one-third flux quantum in kagome superconductors, linked to sublattice degrees of freedom.

Findings

Fractional vortices carry one-third of the flux quantum.

Vortices exhibit signatures related to kagome sublattices.

Results align with recent experimental evidence.

Abstract

We perform a theoretical investigation of the nature of vortices in chiral $d+id$ superconductors on the kagome lattice. The study is motivated by recent experimental developments reporting evidence of time-reversal symmetry breaking in the superconducting state of kagome metals. Using self-consistent microscopic calculations that incorporate the characteristics of the band structure of the kagome lattice, we find that fractional vortices permeate the ground state condensate in the presence of an external field. Each fractional vortex carries one third of the superconducting flux quantum and exhibits a characteristic signature related to one of the three sublattice degrees of freedom of the kagome lattice. We discuss the relevance of these results to recent experimental studies of kagome superconductors in the presence of an external magnetic field.