# Excitonic mass gap in uniaxially strained graphene

## TL;DR

This paper investigates how uniaxial strain in graphene influences the formation of an excitonic mass gap due to Coulomb interactions, revealing that anisotropy lowers the critical coupling needed for gap generation.

## Contribution

It provides a self-consistent numerical analysis of excitonic gap formation in anisotropic graphene, highlighting the role of strain-induced velocity anisotropy.

## Key findings

- Uniaxial strain reduces the critical coupling for gap formation.
- The mass gap depends on momentum and velocity anisotropy.
- Anisotropy supports the formation of an excitonic mass gap.

## 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.