Spin Versus Charge Density Wave Order in Graphene-like Systems

TL;DR

This paper investigates how strong interactions in graphene-like systems favor charge density wave order over spin density waves, revealing effects on quasiparticle velocities and gaps.

Contribution

It introduces a variational approach to compare charge and spin density wave orders, highlighting the dominance of charge order in realistic interaction regimes.

Findings

Charge density wave order is favored over spin density wave in strong interaction regimes.

Introduction of staggered on-site energy causes splitting of quasiparticle velocities and gaps.

Charge density wave Mott insulator is the preferred ground state under certain conditions.

Abstract

A variational technique is used to study sublattice symmetry breaking by strong on-site and nearest neighbor interactions in graphene. When interactions are strong enough to break sublattice symmetry, and with relative strengths characteristic of graphene, a charge density wave Mott insulator is favored over the spin density wave condensates. In the spin density wave condensate we find that introduction of a staggered on-site energy (quasiparticle mass) leads to a splitting of the fermi velocities and mass gaps of the quasiparticle spin states.