title: Massive Dirac fermions and Hofstadter butterfly in a van der Waals heterostructure.
abstract: van der Waals heterostructures constitute a new class of artificial materials formed by stacking atomically thin planar crystals. We demonstrated band structure engineering in 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 in both a local breaking of the carbon sublattice symmetry and a long-range moiré superlattice potential in the graphene. In our samples, this interplay between short- and long-wavelength effects resulted in a band structure described by isolated superlattice minibands and an unexpectedly large band gap at charge neutrality. This picture is confirmed by our observation of fractional quantum Hall states at ± 5/3 filling and features associated with the Hofstadter butterfly at ultrahigh magnetic fields.
authors.affiliation: Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: B
authors.initials: B
authors.lastname: Hunt
authors.forename: J D
authors.initials: JD
authors.lastname: Sanchez-Yamagishi
authors.forename: A F
authors.initials: AF
authors.lastname: Young
authors.forename: M
authors.initials: M
authors.lastname: Yankowitz
authors.forename: B J
authors.initials: BJ
authors.lastname: LeRoy
authors.forename: K
authors.initials: K
authors.lastname: Watanabe
authors.forename: T
authors.initials: T
authors.lastname: Taniguchi
authors.forename: P
authors.initials: P
authors.lastname: Moon
authors.forename: M
authors.initials: M
authors.lastname: Koshino
authors.forename: P
authors.initials: P
authors.lastname: Jarillo-Herrero
authors.forename: R C
authors.initials: RC
authors.lastname: Ashoori