Massive Dirac fermions and Hofstadter butterfly in a van der Waals heterostructure

Understand

Van der Waals heterostructures comprise a new class of artificial materials formed by stacking atomically-thin planar crystals.

• Here, we demonstrate band structure engineering of a van der Waals heterostructure composed of a monolayer graphene flake coupled to a rotationally-aligned hexagonal boron nitride substrate.
• The spatially-varying interlayer atomic registry results both in a local breaking of the carbon sublattice symmetry and a long-range moir\'e superlattice potential in the graphene.
• This interplay between short- and long-wavelength effects results in a band structure described by isolated superlattice minibands and an unexpectedly large band gap at charge neutrality, both of which can be tuned by varying the interlayer alignment.