Spontaneous mass gap generation in monolayer graphene with strong coupling expansion of square/honeycomb lattice gauge theory

Abstract

Sublattice symmetry of the honeycomb lattice of monolayer graphene, which can be extended to a continuous chiral symmetry of Dirac fermions in the continuum limit, may be spontaneously broken due to effectively strong Coulomb interaction between electrons on the vacuum-suspended graphene. We analyze this mechanism by strong coupling expansion of lattice gauge theory, which is constructed with the original honeycomb lattice structure. Spontaneous sublattice symmetry breaking in the strong coupling limit is shown, and is compared with the result obtained from the square lattice formulation qualitatively and quantitatively. We also introduce the Kekulé distortion of the honeycomb lattice externally, and show a restoration of the sublattice symmetry at finite distortion amplitude.