Long-Range Rhombohedral-Stacked Graphene through Shear.

Jean Paul Nery,Matteo Calandra,Francesco Mauri

doi:10.1021/acs.nanolett.0c01146

Abstract

The discovery of superconductivity and correlated electronic states in the flat bands of twisted bilayer graphene has raised a lot of excitement. Flat bands also occur in multilayer graphene flakes that present rhombohedral (ABC) stacking order on many consecutive layers. Although Bernal-stacked (AB) graphene is more stable, long-range ABC-ordered flakes involving up to 50 layers have been surprisingly observed in natural samples. Here, we present a microscopic atomistic model, based on first-principles density functional theory calculations, that demonstrates how shear stress can produce long-range ABC order. A stress-angle phase diagram shows under which conditions ABC-stacked graphene can be obtained, providing an experimental guide for its synthesis.

Highlights

The discovery of superconductivity and correlated electronic states in the flat bands of twisted bilayer graphene has raised a lot of excitement
The main interest in rhombohedralstacked multilayer graphene (RG) stems from its flat bands close to the Fermi energy,[1,2] which could lead to exciting phenomena such as superconductivity,[3−6] charge-density wave, or magnetic orders.[7]
X-ray diffraction experiments[10,17] have shown that some natural samples contain small amounts of rhombohedral graphite. Such experiments have not determined if the stacking is random, or if there are many consecutive layers of ABC-stacked graphene, namely, if there is a phase separation between Bernal-stacked multilayer graphene (BG) and RG

Summary

Introduction

The discovery of superconductivity and correlated electronic states in the flat bands of twisted bilayer graphene has raised a lot of excitement. DFT calculations section in the Supporting Information), which we refer to as potential, of a two-layer graphene system, where the upper layer moves with respect to the lower one along the armchair direction.

Results

Conclusion