title: Tuning the valley and chiral quantum state of Dirac electrons in van der Waals heterostructures.
abstract: Chirality is a fundamental property of electrons with the relativistic spectrum found in graphene and topological insulators. It plays a crucial role in relativistic phenomena, such as Klein tunneling, but it is difficult to visualize directly. Here, we report the direct observation and manipulation of chirality and pseudospin polarization in the tunneling of electrons between two almost perfectly aligned graphene crystals. We use a strong in-plane magnetic field as a tool to resolve the contributions of the chiral electronic states that have a phase difference between the two components of their vector wave function. Our experiments not only shed light on chirality, but also demonstrate a technique for preparing graphene's Dirac electrons in a particular quantum chiral state in a selected valley.
authors: National Graphene Institute, University of Manchester, Manchester M13 9PL, UK. School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK.
authors: J R
authors: JR
authors: Wallbank
authors: School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK.
authors: D
authors: D
authors: Ghazaryan
authors: School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK.
authors: A
authors: A
authors: Misra
authors: Centre for Mesoscience and Nanotechnology, University of Manchester, Manchester M13 9PL, UK.
authors: Y
authors: Y
authors: Cao
authors: Centre for Mesoscience and Nanotechnology, University of Manchester, Manchester M13 9PL, UK.
authors: J S
authors: JS
authors: Tu
authors: Laboratoire National des Champs Magnétiques Intenses, LNCMI-CNRS-UGA-UPS-INSA-EMFL, 25 avenue des Martyrs, 38042 Grenoble, France.
authors: B A
authors: BA
authors: Piot
authors: Laboratoire National des Champs Magnétiques Intenses, LNCMI-CNRS-UGA-UPS-INSA-EMFL, 25 avenue des Martyrs, 38042 Grenoble, France.
authors: M
authors: M
authors: Potemski
authors: High Field Magnet Laboratory (HFML-EMFL) and Institute of Molecules and Materials, Radboud University, Nijmegen, 6525 ED, Netherlands.
authors: S
authors: S
authors: Pezzini
authors: High Field Magnet Laboratory (HFML-EMFL) and Institute of Molecules and Materials, Radboud University, Nijmegen, 6525 ED, Netherlands.
authors: S
authors: S
authors: Wiedmann
authors: High Field Magnet Laboratory (HFML-EMFL) and Institute of Molecules and Materials, Radboud University, Nijmegen, 6525 ED, Netherlands.
authors: U
authors: U
authors: Zeitler
authors: National Graphene Institute, University of Manchester, Manchester M13 9PL, UK. School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK.
authors: T L M
authors: TL
authors: Lane
authors: School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK. Institute of Microelectronics Technology and High Purity Materials, RAS, Chernogolovka 142432, Russia. National University of Science and Technology "MISiS", 119049, Leninsky pr. 4, Moscow, Russia.
authors: S V
authors: SV
authors: Morozov
authors: School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK.
authors: M T
authors: MT
authors: Greenaway
authors: School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK. School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK.
authors: L
authors: L
authors: Eaves
authors: Centre for Mesoscience and Nanotechnology, University of Manchester, Manchester M13 9PL, UK.
authors: A K
authors: AK
authors: Geim
authors: National Graphene Institute, University of Manchester, Manchester M13 9PL, UK. School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK. vladimir.falko@manchester.ac.uk kostya@manchester.ac.uk artem.mishchenko@manchester.ac.uk.
authors: V I
authors: VI
authors: Fal'ko
authors: National Graphene Institute, University of Manchester, Manchester M13 9PL, UK. School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK. vladimir.falko@manchester.ac.uk kostya@manchester.ac.uk artem.mishchenko@manchester.ac.uk.
authors: K S
authors: KS
authors: Novoselov
authors: National Graphene Institute, University of Manchester, Manchester M13 9PL, UK. School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK. vladimir.falko@manchester.ac.uk kostya@manchester.ac.uk artem.mishchenko@manchester.ac.uk.
authors: A
authors: A
authors: Mishchenko