title: Detecting topological currents in graphene superlattices.
abstract: Topological materials may exhibit Hall-like currents flowing transversely to the applied electric field even in the absence of a magnetic field. In graphene superlattices, which have broken inversion symmetry, topological currents originating from graphene's two valleys are predicted to flow in opposite directions and combine to produce long-range charge neutral flow. We observed this effect as a nonlocal voltage at zero magnetic field in a narrow energy range near Dirac points at distances as large as several micrometers away from the nominal current path. Locally, topological currents are comparable in strength with the applied current, indicating large valley-Hall angles. The long-range character of topological currents and their transistor-like control by means of gate voltage can be exploited for information processing based on valley degrees of freedom.
authors.affiliation: Centre for Mesoscience and Nanotechnology, University of Manchester, Manchester M13 9PL, UK. School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
authors.forename: R V
authors.initials: RV
authors.lastname: Gorbachev
authors.affiliation: Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
authors.forename: J C W
authors.initials: JC
authors.lastname: Song
authors.affiliation: Centre for Mesoscience and Nanotechnology, University of Manchester, Manchester M13 9PL, UK.
authors.forename: G L
authors.initials: GL
authors.lastname: Yu
authors.affiliation: School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
authors.forename: A V
authors.initials: AV
authors.lastname: Kretinin
authors.affiliation: School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
authors.forename: F
authors.initials: F
authors.lastname: Withers
authors.affiliation: Centre for Mesoscience and Nanotechnology, University of Manchester, Manchester M13 9PL, UK.
authors.forename: Y
authors.initials: Y
authors.lastname: Cao
authors.affiliation: Centre for Mesoscience and Nanotechnology, University of Manchester, Manchester M13 9PL, UK.
authors.forename: A
authors.initials: A
authors.lastname: Mishchenko
authors.affiliation: School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
authors.forename: I V
authors.initials: IV
authors.lastname: Grigorieva
authors.affiliation: School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
authors.forename: K S
authors.initials: KS
authors.lastname: Novoselov
authors.affiliation: Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: L S
authors.initials: LS
authors.lastname: Levitov
authors.affiliation: Centre for Mesoscience and Nanotechnology, University of Manchester, Manchester M13 9PL, UK. School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK. levitov@mit.edu geim@manchester.ac.uk.
authors.forename: A K
authors.initials: AK
authors.lastname: Geim