Non-Abelian SU(2) gauge fields through density-wave order and strain in graphene

TL;DR

This paper reveals that strain in graphene induces a non-Abelian SU(2) gauge field involving charge-density waves, leading to pseudo-Landau-level quantization and potential density-wave order with dislocations.

Contribution

It identifies the non-Abelian SU(2) gauge field components in strained graphene and links them to charge-density waves, providing a new understanding of strain effects on electronic properties.

Findings

Strain acts as a component of an SU(2) gauge field in graphene.

Spatially varied density-waves cause pseudo-Landau-level quantization.

Strain can induce density-wave order and dislocations in graphene.

Abstract

Spatially varying strain patterns can qualitatively alter the electronic properties of graphene, acting as effective valley-dependent magnetic fields and giving rise to pseudo-Landau-level (PLL) quantization. Here, we show that the strain-induced magnetic field is one component of an SU(2) non-Abelian gauge field within the low-energy theory of graphene, and identify the other two components as period-3 charge-density waves. We show that these density-waves, if spatially varied, give rise to PLL quantization. We also argue that strain-induced magnetic fields can induce density-wave order in graphene, thus dynamically gapping out the lowest PLL; moreover, the ordering should generically be accompanied by dislocations. We discuss experimental signatures of these effects.