Moire engineering in van der Waals heterostructures

Isolated atomic planes can be assembled into a multilayer van der Waals (vdW) heterostructure in a precisely chosen sequence. These heterostructures feature moir & eacute; patterns if the constituent 2D material layers are stacked in an incommensurable way, due to a lattice mismatch or twist. This design-by-stacking has opened up the promising area of moir & eacute; engineering, a term that can be understood in two different perspectives, namely, (i) structural & mdash;engineering a moir & eacute; pattern by introducing twist, relative strain, or defects that affect the commensurability of the layers and (ii) functional & mdash;exploiting a moir & eacute; pattern to find and tune resulting physical properties of a vdW heterostructure. The latter meaning, referring to the application of a moir & eacute; pattern, is seen in the literature in the specific context of the observation of correlated electronic states and unconventional superconductivity in twisted bilayer graphene. The former meaning, referring to the design of the moir & eacute; pattern itself, is present in the literature but less commonly discussed or less understood. The underlying link between these two perspectives lies in the deformation field of the moir & eacute; superlattice. In this Perspective, we describe a path from designing a moir & eacute; pattern to employing the moir & eacute; pattern to tune physical properties of a vdW heterostructure. We also discuss the concept of moir & eacute; engineering in the context of twistronics, strain engineering, and defect engineering in vdW heterostructures. Although twistronics is always associated with moir & eacute; superlattices, strain and defect engineering are often not. Here, we demonstrate how strain and defect engineering can be understood within the context of moir & eacute; engineering. Adopting this perspective, we note that moir & eacute; engineering creates a compelling opportunity to design and develop multiscale electronic devices. Published under an exclusive license by AIP Publishing.