Topological Valley Currents in Bilayer Graphene/Hexagonal Boron Nitride Superlattices
arXiv:1903.00625 · doi:10.1063/1.5094456
Abstract
Graphene superlattices have recently been attracting growing interest as an emergent class of quantum metamaterials. In this paper, we report the observation of nonlocal transport in bilayer graphene (BLG) superlattices encapsulated between two hexagonal boron nitride (hBN) layers, which formed hBN/BLG/hBN moiré superlattices. We then employed these superlattices to detect a long-range charge-neutral valley current using an all-electrical method. The moiré superlattice with broken inversion symmetry leads to a hot spot with Berry curvature accumulating at the charge neutral point (CNP), and it harbors satellites of the CNP. We observed nonlocal resistance on the order of 1 , which obeys a scaling relation. This nonlocal resistance evolves from the quantum Hall effect but without magnetic field/time-reversal symmetry breaking, which is associated with a hot-spot-induced topological valley current. This study should pave the way to developing a Berry-phase-sensitive probe to detect hot spots in gapped Dirac materials with inversion-symmetry breaking.
arXiv comment9 pages, 3 figures
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- Long-range nontopological edge currents in charge-neutral graphene
- Valley Hall Effect and Non-Local Resistance in Locally Gapped Graphene
- Enhanced electron-phonon coupling in doubly aligned hexagonal boron nitride bilayer graphene heterostructure
- Narrow bands, electrostatic interactions and band topology in graphene stacks
- Non-identical moiré twins in bilayer graphene
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- Valley current generation using biased bilayer graphene dots
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