A Pathway between Bernal and Rhombohedral Stacked Graphene Layers with Scanning Tunneling Microscopy

TL;DR

This study investigates how STM tip-induced shifts in graphene layers alter stacking configurations, combining experimental imaging with density functional theory to identify low-energy pathways between Bernal and rhombohedral stacking.

Contribution

It provides a detailed analysis of layer displacement pathways in graphene, revealing the energy barriers and atomic configurations involved, supported by both experimental and theoretical methods.

Findings

STM images match density functional theory simulations

Low-energy barrier displacement leads to ABC stacking

Only one bond length shift needed to convert ABA to ABC

Abstract

Horizontal shifts in the top layer of highly oriented pyrolytic graphite, induced by a scanning tunneling microscope (STM) tip, are presented. Excellent agreement is found between STM images and those simulated using density functional theory. First-principle calculations identify that the low-energy barrier direction of the top layer displacement is toward a structure where none of the carbon pz orbitals overlap, while the high-energy barrier direction is toward AA stacking. Each directional shift yields a real-space surface charge density similar to graphene; however the low-energy barrier direction requires only one bond length to convert ABA (Bernal) to ABC (rhombohedral).