Effects of electron-electron interactions in suspended graphene

TL;DR

This paper studies how electron-electron interactions affect the electronic properties of suspended graphene, finding that velocity renormalization prevents gap formation, aligning with experimental observations of its semimetal phase.

Contribution

It provides a theoretical analysis of dynamical gap generation in suspended graphene considering Coulomb interactions and velocity renormalization effects.

Findings

Critical coupling constant for gap formation is higher than the bare coupling.

Velocity renormalization prevents the emergence of a gapped phase.

Results agree with experimental observations of semimetallic behavior.

Abstract

We investigate the problem of dynamical gap generation in suspended graphene by long-range Coulomb interactions at strong coupling with Dyson-Schwinger equations. Including renormalization effects on the Fermi velocity we obtain a critical coupling constant $\alpha_c=2.85$ which is larger than the bare coupling $\alpha_0=2.19$ of suspended graphene. This suggests that at low energies the running of the Fermi velocity prevents the emergence of a gapped phase. Our calculation is thus in agreement with the experimental observation that suspended graphene remains in the semimetal phase.