Infrared absorption by graphene-hBN heterostructures

TL;DR

This paper develops a theoretical model for optical absorption in graphene-hBN heterostructures, showing how moiré superlattice effects alter infrared to visible photon absorption based on symmetry and band structure modifications.

Contribution

It introduces a theory linking moiré superlattice potentials to changes in optical absorption spectra in graphene-hBN heterostructures.

Findings

Absorption spectrum is significantly affected by moiré superlattice effects.

The absorption depends on the symmetry-allowed couplings and band structure reconstruction.

The theory predicts specific modifications in infrared to visible frequency absorption.

Abstract

We propose a theory of optical absorption in monolayer graphene-hexagonal boron nitride (hBN) heterostructures. In highly oriented heterostructures, the hBN underlay produces a long-range moir\'e superlattice potential for the graphene electrons which modifies the selection rules for absorption of incoming photons in the infrared to visible frequency range. The details of the absorption spectrum modification depend on the relative strength of the various symmetry-allowed couplings between the graphene electrons and the hBN, and the resulting nature of the reconstructed band structure.