Semimetal-antiferromagnetic insulator transition in graphene induced by biaxial strain

TL;DR

This study uses first-principles calculations to show that biaxial strain induces a transition in graphene from a semimetal to an antiferromagnetic insulator with a significant band gap, highlighting the interplay of electron interactions.

Contribution

It reveals the strain-induced antiferromagnetic insulator phase in graphene and explores its competition with Peierls distortions, providing new insights into strain-engineered electronic phases.

Findings

Graphene becomes an antiferromagnetic insulator at 7.7% biaxial strain.

The band gap reaches 0.9 eV at 12% strain.

Antiferromagnetic phase impedes Peierls distortions.

Abstract

We report first-principles calculations on antiferromagnetic spin ordering in graphene under biaxial strain. Using hybrid functional calculations, we found that semimetallic graphene sheets undergo a transition to antiferromagnetic insulators at a biaxial strain of 7.7% and that the band gap rapidly increases after the onset of this transition before reaching 0.9 eV at a biaxial strain of 12%. We examined the competition of the antiferromagnetic spin ordering with two-dimensional Peierls distortions upon biaxial strain, and found that the preceding antiferromagnetic insulator phase impedes the Peierls insulator phase. The antiferromagnetic insulator phase is destabilized upon carrier filling but robust up to moderate carrier densities. This work indicates that biaxially strained graphene represents a noble system where the electron-electron and electron-lattice interactions compete with each other in a simple but nontrivial way.