Local spectroscopy of moir\'e-induced electronic structure in gate-tunable twisted bilayer graphene

TL;DR

This study uses scanning tunneling microscopy to explore the electronic structure of gate-tunable twisted bilayer graphene supported on hexagonal boron nitride, revealing complex moiré patterns and non-perturbative interlayer coupling effects.

Contribution

It provides detailed local spectroscopic analysis of moiré-induced electronic features in tBLG, supported by a theoretical model incorporating ab initio calculations.

Findings

Identification of coexisting moiré patterns and superlattices.

Observation of spectroscopic features beyond the first van Hove singularity.

Confirmation of strongly non-perturbative interlayer coupling in small twist angles.

Abstract

Twisted bilayer graphene (tBLG) forms a quasicrystal whose structural and electronic properties depend on the angle of rotation between its layers. Here we present a scanning tunneling microscopy study of gate-tunable tBLG devices supported by atomically-smooth and chemically inert hexagonal boron nitride (BN). The high quality of these tBLG devices allows identification of coexisting moir\'e patterns and moir\'e super-superlattices produced by graphene-graphene and graphene-BN interlayer interactions. Furthermore, we examine additional tBLG spectroscopic features in the local density of states beyond the first van Hove singularity. Our experimental data is explained by a theory of moir\'e bands that incorporates ab initio calculations and confirms the strongly non-perturbative character of tBLG interlayer coupling in the small twist-angle regime.