Phase interference for probing topological fractional charge in a BiSbTeSe2-based Josephson junction array

J.M. Brevoord, D.H. Wielens, M. Lankhorst, J. Díez-Mérida, Y. Huang, C. Li*, A. Brinkman

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

Fractional charges can be induced by magnetic fluxes at the interface between a topological insulator (TI) and a type-II superconductor due to axion electrodynamics. In a Josephson junction array with a hole in the middle, these electronic states can have phase interference in an applied magnetic field with 4 × 2π period, in addition to the 2π interference of the Cooper pairs. Here, we test an experimental configuration for probing the fractional charge and report the observation of phase interference effect in superconducting arrays with a hole in the middle in both Au- and TI-based devices. Our numerical simulations based on resistive shunted capacitive junction model are in good agreement with the experimental results. However, no clear sign of an axion charge-related interference effect was observed. We will discuss possible reasons and perspectives for future experiments.

Original languageEnglish
Article number435001
JournalNanotechnology
Volume32
Issue number43
DOIs
Publication statusPublished - 2 Aug 2021

Keywords

  • UT-Hybrid-D
  • topological insulator
  • phase interference
  • topological superconductivity
  • Josephson junction arrays
  • fractional charge

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