Superlattice structures in twisted bilayers of folded graphene

TL;DR

This paper investigates how twisting bilayer graphene affects its electronic properties, revealing superlattice formations and satellite Landau fans that depend on the twist angle, with implications for understanding interlayer coupling.

Contribution

It provides experimental evidence of superlattice structures and satellite Landau fans in twisted bilayer graphene, highlighting the angle-dependent electronic phenomena.

Findings

Superlattices with ~10 nm wavelength form at small twist angles.

Satellite Landau fans indicate additional Dirac points.

Strong dependence of electronic properties on twist angle.

Abstract

The electronic properties of bilayer graphene strongly depend on relative orientation of the two atomic lattices. Whereas Bernal-stacked graphene is most commonly studied, a rotational mismatch between layers opens up a whole new field of rich physics, especially at small interlayer twist. Here we report on magnetotransport measurements on twisted graphene bilayers, prepared by folding of single layers. These reveal a strong dependence on the twist angle, which can be estimated by means of sample geometry. At small rotation, superlattices with a wavelength in the order of 10 nm arise and are observed by friction atomic force microscopy. Magnetotransport measurements in this small-angle regime show the formation of satellite Landau fans. These are attributed to additional Dirac singularities in the band structure and discussed with respect to the wide range of interlayer coupling models.