Optical transparency of graphene as determined by the fine-structure constant

TL;DR

This paper explains the near-perfect optical transparency of graphene by linking it to the fine-structure constant, showing Coulomb interactions have minimal impact on its optical properties.

Contribution

It provides a theoretical calculation of Coulomb interaction corrections to graphene's optical conductivity, clarifying their negligible effect on transparency.

Findings

Coulomb interactions cause only 1-2% correction to optical conductivity

Optical transparency of graphene is fundamentally connected to the fine-structure constant

Corrections to transparency are about 0.03-0.04%

Abstract

The observed 97.7% optical transparency of graphene has been linked to the value 1/137 of the fine structure constant, by using results for noninteracting Dirac fermions. The agreement in three significant figures requires an explanation for the apparent unimportance of the Coulomb interaction. Using arguments based on Ward identities, the leading corrections to the optical conductivity due to the Coulomb interactions are correctly computed (resolving a subtle theoretical issue) and shown to amount to only 1-2%, corresponding to 0.03-0.04% in the transparency.