Mapping the twist angle dependence of quasi-Brillouin zones in doubly aligned graphene/BN heterostructures

TL;DR

This study maps how the twist angle between graphene and BN layers affects the formation of quasi-Brillouin zones in double-moiré heterostructures, revealing new electronic interference phenomena through in situ charge transport measurements.

Contribution

It provides the first experimental mapping of quasi-Brillouin zones as a function of twist angle in double-moiré graphene/BN heterostructures, linking moiré interference to electronic structure modifications.

Findings

Identification of signatures of moiré superlattices and quasi-Brillouin zones in charge transport data.

Demonstration of in situ control of BN alignment and its effect on electronic properties.

Correlation between theoretical models and experimental qBZ mappings.

Abstract

When monolayer graphene is crystallographically aligned to hexagonal boron nitride (BN), a moir\'e superlattice is formed, producing characteristic satellite Dirac peaks in the electronic band structure. Aligning a second BN layer to graphene creates two coexisting moir\'e patterns, which can interfere to produce periodic, quasi-periodic or non-periodic superlattices, depending on their relative alignment. Here, we investigate one of the simplest realizations of such a double-moir\'e structure, graphene encapsulated between two BN layers, using dynamically rotatable van der Waals heterostructures. Our setup allows \textit{in situ} control of the top BN alignment while keeping the bottom BN fixed. By systematically mapping the charge transport as a function of BN angular alignment, we identify the simultaneous signatures of the original moir\'es, super-moir\'es, and a third set of features corresponding to quasi-Brillouin zones (qBZ) formed when the system's periodicity becomes ill-defined. Comparing our measurements with theoretical models, we provide the first experimental mapping of the qBZs as a function of angular alignment. Our results establish a direct experimental link between moir\'e interference and qBZ formation, opening new avenues for engineering electronic structures in multi-aligned 2D heterostructures.