Non-identical moiré twins in bilayer graphene

Abstract

The superlattice obtained by aligning a monolayer graphene and boron nitride (BN) inherits from the hexagonal lattice a sixty degrees periodicity with the layer alignment. It implies that, in principle, the properties of the heterostructure must be identical for 0${}^{\circ }$ and 60${}^{\circ }$ of layer alignment. Here, we demonstrate, using dynamically rotatable van der Waals heterostructures, that the moiré superlattice formed in a bilayer graphene/BN has different electronic properties at 0${}^{\circ }$ and 60${}^{\circ }$ of alignment. Although the existence of these non-identical moiré twins is explained by different relaxation of the atomic structures for each alignment, the origin of the observed valley Hall effect remains to be explained. A simple Berry curvature argument do not hold to explain the hundred and twenty degrees periodicity of this observation. Our results highlight the complexity of the interplay between mechanical and electronic properties on moiré structure and the importance of taking into account atomic structure relaxation to understand its electronic properties.

References in corpus (11)

• Detecting Topological Currents in Graphene Superlattices
• Proximity-induced ferromagnetism in graphene revealed by anomalous Hall effect
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• Tunable and giant valley-selective Hall effect in gapped bilayer graphene
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• Nonlocal topological valley transport at large valley Hall angles
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Cited by in corpus (7)

• de Haas-van Alphen spectroscopy and fractional quantization of magnetic-breakdown orbits in moiré graphene
• Non-conservation of the valley density and its implications for the observation of the valley Hall effect
• Klein tunneling degradation and enhanced Fabry-Pérot interference in graphene/h-BN moiré-superlattice devices
• Tunable atomically enhanced moiré Berry curvatures in twisted triple bilayer graphene
• Impact of the angular alignment on the crystal field and intrinsic doping of bilayer graphene/BN heterostructures
• Hexagonal boron nitride/bilayer graphene moiré superlattices in the Dirac-material family: energy-band engineering and carrier doping by dual gating
• Magic-angle twisted bilayer graphene under orthogonal and in-plane magnetic fields