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  • Letter
  • Open Access

Gate-defined superconducting channel in magic-angle twisted bilayer graphene

Giulia Zheng1, Elías Portolés1, Alexandra Mestre-Torà1, Marta Perego1, Takashi Taniguchi2, Kenji Watanabe3, Peter Rickhaus1, Folkert K. de Vries1, Thomas Ihn1,4 et al.

Klaus Ensslin1,4 and Shuichi Iwakiri1,*

  • 1Laboratory for Solid State Physics, ETH Zurich, CH-8093 Zurich, Switzerland
  • 2Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
  • 3Research Center for Electronic and Optical Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
  • 4Quantum Center, ETH Zurich, CH-8093 Zurich, Switzerland

  • *siwakiri@phys.ethz.ch
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Phys. Rev. Research 6, L012051 – Published 6 March, 2024

DOI: https://doi.org/10.1103/PhysRevResearch.6.L012051

Abstract

Magic-angle twisted bilayer graphene (MATBG) combines in one single material different phases such as insulating, metallic, and superconducting. These phases and their in situ tunability make MATBG an important platform for the fabrication of superconducting devices. We realize a split-gate-defined geometry which enables us to tune the width of a superconducting channel formed in MATBG. We observe a smooth transition from superconductivity to highly resistive transport by progressively reducing the channel width using the split gates or by reducing the density in the channel. Using the gate-defined constriction, we control the flow of the supercurrent, either guiding it through the constriction or throughout the whole device or even blocking its passage completely. This serves as a foundation for developing quantum constriction devices such as superconducting quantum point contacts, quantum dots, and Cooper-pair boxes in MATBG.

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Phys. Rev. Research 6, L012051– Published 6 March, 2024
  • Received 18 December 2023
  • Revised 17 January 2024
  • Accepted 29 January 2024
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