Topologically non-trivial valley states in bilayer graphene quantum point contacts

Research output: Contribution to journalArticlepeer-review

  • External authors:
  • Hiske Overweg
  • Thomas Fabian
  • L. Linhart
  • Peter Rickhaus
  • Lucien Wernli,
  • Kenji Watanabe
  • Takashi Taniguchi
  • David Sanchez
  • Joachim Burgdörfer
  • Florian Libisch
  • Klaus Ensslin
  • Thomas Ihn

Abstract

We present measurements of quantized conductance in electrostatically induced quantum point contacts in bilayer graphene. The application of a perpendicular magnetic field leads to an intricate pattern of lifted and restored degeneracies with increasing field: at zero magnetic field the degeneracy of quantized one-dimensional subbands is four, because of a twofold spin and a twofold valley degeneracy. By switching on the magnetic field, the valley degeneracy is lifted. Because of the Berry curvature, states from different valleys split linearly in magnetic field. In the quantum Hall regime fourfold degenerate conductance plateaus reemerge. During the adiabatic transition to the quantum Hall regime, levels from one valley shift by two in quantum number with respect to the other valley, forming an interweaving pattern that can be reproduced by numerical calculations.

Bibliographical metadata

Original languageEnglish
Article number257702
JournalPhysical Review Letters
Volume121
Issue number25
Early online date20 Dec 2018
DOIs
Publication statusPublished - 20 Dec 2018

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