Article Specular Electron Focusing between Gate-Defined Quantum Point Contacts in Bilayer Graphene

Josep Ingla-Aynés ; Antonio L. R. Manesco ; Talieh S. Ghiasi ; Serhii Volosheniuk ; Kenji Watanabe SAMURAI ORCID (National Institute for Materials ScienceROR) ; Takashi Taniguchi SAMURAI ORCID (National Institute for Materials ScienceROR) ; Herre S. J. van der Zant

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Citation
Josep Ingla-Aynés, Antonio L. R. Manesco, Talieh S. Ghiasi, Serhii Volosheniuk, Kenji Watanabe, Takashi Taniguchi, Herre S. J. van der Zant. Specular Electron Focusing between Gate-Defined Quantum Point Contacts in Bilayer Graphene. Nano Letters. 2023, 23 (12), 5453-5459. https://doi.org/10.1021/acs.nanolett.3c00499
SAMURAI

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(abstract)

We report on multiterminal measurements in a ballistic bilayer graphene (BLG) channel where multiple spin and valley-degenerate quantum point contacts (QPCs) are defined by electrostatic gating. By patterning QPCs of different shapes and in different directions, we study the effect of size quantization and trigonal warping on the TEF spectra. Our results from transverse electron focusing (TEF) show eight clear peaks with comparable amplitude and weak signatures of quantum interference at the lowest temperature, indicating that reflections at the gate-defined edges are specular and transport is phase coherent. The temperature dependence of the scattering rates indicates that electron-electron interactions play a dominant role in the charge relaxation process at positive Vbg and for temperatures below 100 K. Our findings thus demonstrate that the BLG tuneable bandgap can be used for the realization of gate-defined ballistic multiterminal devices and form the starting point for new coherent transport experiments in graphene-based devices.

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Keyword: Ballistic bilayer graphene, quantum point contacts, transverse electron focusing

Date published: 2023-06-28

Publisher: American Chemical Society (ACS)

Journal:

  • Nano Letters (ISSN: 15306984) vol. 23 issue. 12 p. 5453-5459

Funding:

  • European Commission 863098
  • Nederlandse Organisatie voor Wetenschappelijk Onderzoek 016.Vidi.189.180
  • European Commission 101027187
  • Ministry of Education, Culture, Sports, Science and Technology 19H05790
  • Ministry of Education, Culture, Sports, Science and Technology 20H00354
  • Ministry of Education, Culture, Sports, Science and Technology 21H05233

Manuscript type: Publisher's version (Version of record)

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First published URL: https://doi.org/10.1021/acs.nanolett.3c00499

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Updated at: 2025-02-14 16:30:48 +0900

Published on MDR: 2025-02-14 16:30:48 +0900

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