Asymmetric Fraunhofer Spectra in a Topological Insulator-based Josephson Junction

Alexander Beach, Dalmau Reig-I-Plessis, Gregory Macdougall, Nadya Mason

Research output: Contribution to journalArticlepeer-review

Abstract

Josephson junctions with topological insulators as their weak link (S-TI-S junctions) are predicted to host Majorana fermions, which are key to creating qubits for topologically protected quantum computing. But the details of the S-TI-S current-phase relation and its interplay with magnetic fields are not well understood. We fabricate a Bi2Se3 junction with NbTi leads and measure the Fraunhofer patterns of the junction with applied in-plane fields. We observe that asymmetric Fraunhofer patterns appear in the resistance maps of B z vs B x,y , with aperiodic node spacings. These asymmetric patterns appear even at zero parallel field and for temperatures up to 1 K. The anomalous features are compared to asymmetric Fraunhofer patterns expected for finite Cooper pair momentum shifts as well as geometric effects. We show that the geometric effects can dominate, independent of in-plane field magnitude. These results are important for differentiating geometrical phase shifts from those caused by Cooper pair momentum shifting, Majorana mode signatures, or other unconventional superconducting behavior.

Original languageEnglish (US)
Article number425601
JournalJournal of Physics Condensed Matter
Volume33
Issue number42
DOIs
StatePublished - Oct 2021

Keywords

  • bismuth selenide
  • Fraunhofer
  • Josephson junction
  • topological insulator

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics

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