Excitonic mass gap in uniaxially strained graphene

Abstract

We study the conditions for spontaneously generating an excitonic mass gap due to Coulomb interactions between anisotropic Dirac fermions in uniaxially strained graphene. The mass gap equation is realized as a self-consistent solution for the self-energy within the Hartree-Fock mean-field and static random phase approximations. It depends not only on momentum, due to the long-range nature of the interaction, but also on the velocity anisotropy caused by the presence of uniaxial strain. We solve the nonlinear integral equation self-consistently by performing large scale numerical calculations on variable grid sizes. We evaluate the mass gap at the charge neutrality (Dirac) point as a function of the dimensionless coupling constant and anisotropy parameter. We also obtain the phase diagram of the critical coupling, at which the gap becomes finite, against velocity anisotropy. Our numerical study indicates that with an increase in uniaxial strain in graphene the strength of critical coupling decreases, which suggests anisotropy supports formation of excitonic mass gap in graphene.

8 pages, 5 figures. Accepted Phys. Rev. B version with a new figure and revised text

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• Electron-polaron--electron-polaron bound states in mass-gap graphene-like planar quantum electrodynamics: $s$-wave bipolarons
• Dynamical gap generation in 2D Dirac semimetal with deformed Dirac cone
• Lattice field theory simulations of Dirac semimetals
• The effect of anisotropy on phase transitions in graphene
• Proximity-induced topological transition and strain-induced charge transfer in graphene/MoS2 bilayer heterostructures
• Robustness of the semimetal state of Na3Bi and Cd3As2 against Coulomb interaction
• Theory for strained graphene beyond the Cauchy-Born rule
• Quantum critical phenomena of the excitonic insulating transition in two dimensions
• Effects of different 3D QED vertex ansaetze on critical coupling
• Phase transitions in anisotropic graphene