Controlled alignment of supermoir\'e lattice in double-aligned graphene heterostructures

TL;DR

This paper presents an experimental method to precisely control the rotational alignment of supermoiré lattices in graphene heterostructures, enabling better flat-band engineering and study of electron correlations.

Contribution

The authors develop a strategy using the crystallographic edge of graphite to achieve deterministic alignment of double-aligned graphene supermoiré lattices with high precision.

Findings

Achieved alignment accuracy better than 0.2 degrees in 20 samples.

Demonstrated controlled production of supermoiré lattices.

Extended the technique to other moiré systems like twisted bilayer graphene.

Abstract

The supermoir\'e lattice, built by stacking two moir\'e patterns, provides a platform for creating flat mini-bands and studying electron correlations. An ultimate challenge in assembling a graphene supermoir\'e lattice is in the deterministic control of its rotational alignment, which is made highly aleatory due to the random nature of the edge chirality and crystal symmetry of each component layer. Employing the so-called golden rule of three, here we present an experimental strategy to overcome this challenge and realize the controlled alignment of double-aligned hBN/graphene/hBN supermoir\'e lattice, where graphene is precisely aligned with both top hBN and bottom hBN. Remarkably, we find that the crystallographic edge of neighboring graphite can be used to better guide the stacking alignment, as demonstrated by the controlled production of 20 moir\'e samples with an accuracy better than 0.2 degree. Finally, we extend our technique to other strongly correlated electron systems, such as low-angle twisted bilayer graphene and ABC-stacked trilayer graphene, providing a strategy for flat-band engineering in these moir\'e materials.