Effect of next-nearest neighbor coupling on the optical spectra in bilayer graphene

TL;DR

This paper explores how next-nearest neighbor interactions affect the optical conductivity of bilayer graphene, revealing new spectral features and anisotropies that depend on doping and interlayer coupling.

Contribution

It introduces a comprehensive model showing the significant impact of intra- and inter-layer couplings on bilayer graphene's optical spectra, especially the role of next-nearest neighbor interactions.

Findings

Next-nearest neighbor intralayer coupling alters low-energy spectral features.

Interlayer couplings induce anisotropy in ultraviolet conductance.

Optical measurements can benchmark intra- and inter-layer interactions.

Abstract

We investigate the dependence of the optical conductivity of bilayer graphene (BLG) on the intra- and inter-layer interactions using the most complete model to date. We show that the next nearest-neighbor intralayer coupling introduces new features in the low-energy spectrum that are highly sensitive to sample doping, changing significantly the ``universal'' conductance. Further, its interplay with interlayer couplings leads to an anisotropy in conductance in the ultraviolet range. We propose that experimental measurement of the optical conductivity of intrinsic and doped BLG will provide a good benchmark for the relative importance of intra- and inter-layer couplings at different doping levels.