Dynamic band structure tuning of graphene moir\'e superlattices with pressure

TL;DR

This study demonstrates that applying hydrostatic pressure to graphene on boron nitride significantly enhances the primary Dirac point gap, revealing a new method for band structure engineering in van der Waals heterostructures.

Contribution

It introduces pressure as a novel tuning parameter to control interlayer coupling and band gaps in graphene heterostructures, expanding the toolkit for electronic property manipulation.

Findings

DP gap increases with pressure

SDP gap remains largely unchanged

Pressure induces atomic-scale structural deformations

Abstract

Heterostructures of atomically-thin materials have attracted significant interest owing to their ability to host novel electronic properties fundamentally distinct from their constituent layers. In the case of graphene on boron nitride, the closely-matched lattices yield a moir\'e superlattice that modifies the graphene electron dispersion and opens gaps both at the primary Dirac point (DP) and the moir\'e-induced secondary Dirac point (SDP) in the valence band. While significant effort has focused on controlling the superlattice period via the rotational stacking order, the role played by the magnitude of the interlayer coupling has received comparatively little attention. Here, we modify the interaction between graphene and boron nitride by tuning their separation with hydrostatic pressure. We observe a dramatic enhancement of the DP gap with increasing pressure, but little change in the SDP gap. Our surprising results identify the critical role played by atomic-scale structural deformations of the graphene lattice and reveal new opportunities for band structure engineering in van der Waals heterostructures.