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Dynamic band structure tuning of graphene moire superlattice under pressure

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Document pages: 19 pages

Abstract: Heterostructures can be assembled from atomic thin materials by combining various available van der Waals crystals, which provides exciting possibilities for the design of electronic products 1. In many cases, in addition to simply realizing new material combinations, the interlayer interaction also leads to the emergence of electronic properties fundamentally different from the constituent layer 2. One of the key parameters in these structures is the interlayer coupling strength, which is usually not easy to determine and is usually considered as a fixed property of the system. Here, we prove that we can use hydrostatic pressure to controllably adjust the interlayer separation in van der Waals heterostructures, thus providing a dynamic method to change their electronic properties. In graphene is encapsulated in boron nitride and aligned with one of the encapsulating layers, we observe that increasing pressure produces a superlinear increase in the moiré-superlattice-induced bandgap—nearly doubling within the studied range—together with an increase in the capacitive gate coupling to the active channel by as much as 25 per cent. Comparison to theoretical modelling highlights the role of atomic-scale structural deformations and how this can be altered with pressure. Our results demonstrate that combining hydrostatic pressure with controlled rotational order provides opportunities for dynamic band-structure engineering in van der Waals heterostructures.

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