Optical conductivity of bilayer graphene with and without an asymmetry gap

TL;DR

This paper analyzes how an asymmetry gap in bilayer graphene affects its optical conductivity, revealing spectral weight redistribution due to tunable gaps and chemical potential changes.

Contribution

It provides a detailed calculation of optical conductivity in gapped bilayer graphene, including an algebraic formula for arbitrary chemical potential values.

Findings

Optical spectral weight shifts with gap and chemical potential changes

Derived algebraic formula for bilayer conductivity without a gap

Demonstrated tunable semiconducting behavior in bilayer graphene

Abstract

When a bilayer of graphene is placed in a suitably configured field effect device, an asymmetry gap can be generated and the carrier concentration made different in each layer. This provides a tunable semiconducting gap, and the valence and the conductance band no longer meet at the two Dirac points of the graphene Brillouin zone. We calculate the optical conductivity of such a semiconductor with particular emphasis on the optical spectral weight redistribution brought about by changes in gap and chemical potential due to charging. We derive an algebraic formula for arbitrary value of the chemical potential for the case of the bilayer conductivity without a gap.