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WTe2 is a layered transitional metal dichalcogenide (TMD) with a number of intriguing topological properties. The bulk crystal is a Weyl semimetal with Fermi arc surface states and the monolayer is a two-dimensional (2D) topological insulator. Recently, WTe2 was also predicted to be a higher-order topological insulator (HOTI) with hinge states along the edges. The gapless nature of WTe2 complicates the observation of one-dimensional (1D) topological states in transport, due to their small contribution relative to the bulk. Here, the Josephson effect can help to detect edge transport, since the evolution of the critical current in magnetic field is sensitive to the spatial current distribution. Here, we employ superconducting contacts in WTe2 that emerge when Pd is placed in contact with the TMD to define Josephson junctions. Using the Josephson effect, we demonstrate the presence of 1D current carrying states residing on the edges and steps of few-layers WTe2 crystals. The width of the 1D current-carrying states is deduced to be below 80 nm. A supercurrent Ic is measured over distances up to 3 μm and persisting in magnetic fields up to B = 2 T. This observation is in good agreement with the recent prediction of HOTI states in WTe2. Moreover, the observed dependencies of Ic(B) on magnetic field demonstrate a particular symmetry with the direction of the current and the magnetic field, which matches the pre- diction for topological states in systems with broken inversion symmetry. Our observation adds another effect to a plethora of intriguing properties of WTe2 and potentially provides a new platform for obtaining Majorana Zero Modes.

Rights:

• Creative Commons BY-NC-ND Attribution-NonCommercial-NoDerivs 4.0 International
  

Keyword: WTe2, topological insulator, Josephson effect

Date published: 2020-06-10

Publisher: American Chemical Society (ACS)

Journal:

• Nano Letters (ISSN: 15306984) vol. 20 issue. 6 p. 4228-4233

Funding:

• Ministry of Education, Culture, Sports, Science and Technology
• Schweizerischer Nationalfonds zur F?rderung der Wissenschaftlichen Forschung
• Core Research for Evolutional Science and Technology JPMJCR15F3
• Office of Science
• H2020 European Research Council 787414
• Georg H. Endress foundation
• Swiss Nanoscience Institute

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

MDR DOI:

First published URL: https://doi.org/10.1021/acs.nanolett.0c00658

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Updated at: 2025-02-26 12:30:59 +0900

Published on MDR: 2025-02-26 12:30:59 +0900