Chirality and Correlations in Graphene

TL;DR

This paper investigates how the chirality of quasiparticles in graphene influences electron interactions, revealing that Coulomb interactions favor states with higher net chirality, leading to suppressed susceptibilities and velocity enhancements near the Dirac point.

Contribution

It demonstrates that quasiparticle chirality in graphene affects Coulomb interactions, resulting in suppressed susceptibilities and increased velocities, based on exchange and RPA correlation energy evaluations.

Findings

Coulomb interactions favor states with larger net chirality in graphene.

Chirality switch enhances quasiparticle velocities near the Dirac point.

Susceptibilities are suppressed due to chirality effects.

Abstract

Graphene is described at low-energy by a massless Dirac equation whose eigenstates have definite chirality. We show that the tendency of Coulomb interactions in lightly doped graphene to favor states with larger net chirality leads to suppressed spin and charge susceptibilities. Our conclusions are based on an evaluation of graphene's exchange and random-phase-approximation (RPA) correlation energies. The suppression is a consequence of the quasiparticle chirality switch which enhances quasiparticle velocities near the Dirac point.