Drude-Interband Coupling, Screening, and the Optical Conductivity of Doped Bilayer Graphene

TL;DR

This paper develops a theoretical framework for understanding how band renormalization and electron interactions affect the optical conductivity of doped bilayer graphene, revealing a new coupling mechanism and emphasizing the importance of screening.

Contribution

It introduces a novel theory incorporating band renormalization and excitonic effects to explain optical conductivity in doped bilayer graphene, highlighting a previously unrecognized coupling mechanism.

Findings

Identifies a new coupling between Drude and interband responses.

Shows that screening significantly influences conductivity.

Renormalizes plasmon frequency in doped bilayer graphene.

Abstract

We present a theory of the influence of band renormalization and excitonic electron-electron interaction effects on the optical conductivity $\sigma(\omega)$ of doped bilayer graphene. Using the Keldysh formalism, we derive a kinetic equation from which we extract numerical and approximate analytic results for $\sigma(\omega)$. Our calculations reveal a previously unrecognized mechanism which couples the Drude and interband response and renormalizes the plasmon frequency, and suggest that screening must play an essential role in explaining the weakly renormalized conductivity seen in recent experiments.