Study of interacting electrons in graphene under the renormalized-ring-diagram approximation

TL;DR

This study investigates the electronic properties of graphene with long-range Coulomb interactions using the renormalized-ring-diagram approximation, revealing Fermi-liquid behavior consistent with experimental observations.

Contribution

It applies the renormalized-ring-diagram approximation to graphene, providing self-consistent calculations of spectral density and other properties, which is a novel approach in this context.

Findings

Spectral density matches experimental data

Imaginary part of self-energy varies quadratically near Fermi level

Electrons in graphene behave as a moderately correlated Fermi liquid

Abstract

Using the tight-binding model with long-range Coulomb interactions between electrons, we study some of the electronic properties of graphene. The Coulomb interactions are treated with the renormalized-ring-diagram approximation. By self-consistently solving the integral equations for the Green function, we calculate the spectral density. The obtained result is in agreement with experimental observation. In addition, we also compute the density of states, the distribution functions, and the ground-state energy. Within the present approximation, we find that the imaginary part of the self-energy fixed at the Fermi momentum varies as quadratic in energy close to the chemical potential, regardless the system is doped or not. This result appears to indicate that the electrons in graphene always behave like a moderately correlated Fermi liquid.