Low-energy band structure and even-odd layer number effect in AB-stacked multilayer graphene

TL;DR

This study systematically investigates how the electronic band structure of AB-stacked multilayer graphene varies with layer number, revealing an even-odd layer effect and the influence of gate-induced potential energy.

Contribution

It provides the first detailed experimental analysis of the layer-dependent band structure and even-odd effects in multilayer graphene using quantum oscillation measurements.

Findings

Distinct Landau fan structures for different layer numbers

Observation of an even-odd layer number effect on band count

Dirac cone present only in odd-layer graphene

Abstract

How atoms acquire three-dimensional bulk character is one of the fundamental questions in materials science. Before addressing this question, how atomic layers become a bulk crystal might give a hint to the answer. While atomically thin films have been studied in a limited range of materials, a recent discovery showing how to mechanically exfoliate bulk crystals has opened up the field to study the atomic layers of various materials. Here, we show systematic variation in the band structure of high mobility graphene with one to seven layers by measuring the quantum oscillation of magnetoresistance. The Landau fan diagram showed distinct structures that reflected differences in the band structure, as if they were finger prints of multilayer graphene. In particular, an even-odd layer number effect was clearly observed, with the number of bands increasing by one for every two layers and a Dirac cone observed only for an odd number of layers. The electronic structure is significantly influenced by the potential energy arising from carrier screening associated with a gate electric field.