Giant Valley-Isospin Conductance Oscillations in Ballistic Graphene

Handschin, Clevin and Makk, Peter and Rickhaus, Peter and Maurand, Romain and Watanabe, Kenji and Taniguch, Takashi and Richter, Klaus and Liu, Ming-Hao and Schonenberger, Christian (2017) Giant Valley-Isospin Conductance Oscillations in Ballistic Graphene. NANO LETTERS, 17 (9). pp. 5389-5393. ISSN 1530-6984, 1530-6992

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Abstract

At high magnetic fields the conductance of graphene is governed by the half-integer quantum Hall effect. By local electrostatic gating a p-n junction perpendicular to the graphene edges can be formed, along which quantum Hall channels copropagate. It has been predicted by Tworzidlo and co-workers that if only the lowest Landau level is filled on both sides of the junction, the conductance is determined by the valley (isospin) polarization at the edges and by the width of the flake. This effect remained hidden so far due to scattering between the channels copropagating along the p-n interface (equilibration). Here we investigate p-n junctions in encapsulated graphene with a movable p-n interface with which we are able to probe the edge configuration of graphene flakes. We observe large quantum conductance oscillations on the order of e(2)/h which solely depend on the p-n junction position providing the first signature of isospin-defined conductance. Our experiments are underlined by quantum transport calculations.

Item Type: Article
Uncontrolled Keywords: P-N-JUNCTIONS; QUANTUM; TRANSPORT; GRAPHITE; STATES; EDGES; Valley-valve; valley isospin; valleytronics; encapsulated graphene; p-n junction; quantum Hall effect
Subjects: 500 Science > 530 Physics
Divisions: Physics > Institute of Theroretical Physics
Physics > Institute of Theroretical Physics > Chair Professor Richter > Group Klaus Richter
Depositing User: Dr. Gernot Deinzer
Date Deposited: 14 Dec 2018 13:15
Last Modified: 20 Feb 2019 07:37
URI: https://pred.uni-regensburg.de/id/eprint/1241

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