Chiral symmetry breaking through spontaneous dimerization in kagom\'e metals

TL;DR

This paper explores how chiral symmetry can spontaneously break in kagome metals, leading to a dimerization that opens a gap at the Dirac point, using a lattice model and mean-field analysis.

Contribution

It introduces a heuristic lattice model to analyze chiral symmetry breaking and identifies dimerization as the leading instability in kagome metals.

Findings

Dimerization pattern causes a gap opening at the Dirac point.

Chiral symmetry breaking occurs at a critical coupling strength.

The study provides a theoretical framework for understanding symmetry breaking in kagome metals.

Abstract

Due to an uprise in the variety of candidate compounds, kagome metals have recently gained significant attention. Among other features, kagome metals host Dirac cones as a key band structure feature away from half filling, and potentially yield an exceptionally large fine structure, beyond values found in other 2D Dirac materials such as graphene. We investigate the possibility of chiral symmetry breaking in kagome metals. Based on a heuristic lattice model, we determine the critical coupling strength and the ordering pattern by means of a Schwinger-Dyson mean-field analysis. As the leading instability we identify a dimerization pattern which spontaneously opens an excitation gap at the Dirac point and breaks the chiral symmetry.