Electronic Structure of Few-Layer Graphene: Experimental Demonstration of Strong Dependence on Stacking Sequence

TL;DR

This study experimentally demonstrates that the stacking sequence in few-layer graphene significantly influences its electronic structure, with distinct optical properties observed for different stacking arrangements and supported by theoretical calculations.

Contribution

It provides the first experimental evidence showing the strong dependence of electronic properties on stacking order in few-layer graphene, validated by tight-binding model calculations.

Findings

Distinct optical conductivity spectra for different stacking sequences

Experimental confirmation of stacking order effects on electronic structure

Theoretical reproduction of absorption features based on symmetry and van Hove singularities

Abstract

The electronic structure of few-layer graphene (FLG) samples with crystalline order was investigated experimentally by infrared absorption spectroscopy for photon energies ranging from 0.2 - 1 eV. Distinct optical conductivity spectra were observed for different samples having precisely the same number of layers. The different spectra arise from the existence of two stable polytypes of FLG, namely, Bernal (AB) stacking and rhombohedral (ABC) stacking. The observed absorption features, reflecting the underlying symmetry of the two polytypes and the nature of the associated van Hone singularities, were reproduced by explicit calculations within a tight-binding model. The findings demonstrate the pronounced effect of stacking order on the electronic structure of FLG.