Universal collisionless transport of graphene

TL;DR

This paper demonstrates that the optical conductivity of graphene is universal and unaffected by electron-electron interactions, confirmed through lattice calculations and theoretical methods that align with experimental results.

Contribution

The study resolves previous controversies by showing the universality of graphene's optical conductivity using lattice calculations and confirms the agreement of different regularization methods.

Findings

Lattice calculations match experimental optical conductivity data.

Dimensional regularization methods agree with lattice results.

Universality of graphene's optical conductivity is confirmed at low energies.

Abstract

The impact of the electron-electron Coulomb interaction on the optical conductivity of graphene has led to a controversy that calls into question the universality of collisionless transport in this and other Dirac materials. Using a lattice calculation that avoids divergences present in previous nodal Dirac approaches, our work settles this controversy and obtains results in quantitative agreement with experiment over a wide frequency range. We also demonstrate that dimensional regularization methods agree, as long as the scaling properties of the conductivity and the regularization of the theory in modified dimension are correctly implemented. Tight-binding lattice and nodal Dirac theory calculations are shown to coincide at low energies even when the non-zero size of the atomic orbital wave function is included, conclusively demonstrating the universality of the optical conductivity of graphene.