Controlling the Interlayer Coupling of Twisted Bilayer Graphene

TL;DR

This paper presents a simple method to control interlayer coupling in twisted bilayer graphene by adsorbing single molecule magnets, allowing tuning of electronic properties as characterized by scanning tunneling microscopy and spectroscopy.

Contribution

It introduces a novel approach to modulate interlayer coupling in twisted bilayer graphene through molecule adsorption, enabling precise electronic property tuning.

Findings

Interlayer coupling affects electronic band structure.

Adsorption density controls the energy difference of Van Hove singularities.

Electronic features like superlattice Dirac cones are observed and tunable.

Abstract

The interlayer coupling of twisted bilayer graphene could markedly affect its electronic band structure. A current challenge required to overcome in experiment is how to precisely control the coupling and therefore tune the electronic properties of the bilayer graphene. Here, we describe a facile method to modulate the local interlayer coupling by adsorption of single molecule magnets onto the twisted bilayer graphene and report the characterization of its electronic band structure using scanning tunneling microscopy and spectroscopy. The low-energy Van Hove singularities (VHSs) and superlattice Dirac cones, induced by the interlayer coupling and graphene-on-graphene moir\'e respectively, are observed in the tunneling spectra. Our experiment demonstrates that the energy difference of the two VHSs, which reflects the magnitude of interlayer coupling, can be tuned by the local coverage density of adsorption.