University of Illinois Urbana-Champaign

Investigation of current-phase relation in topological insulator Josephson junction

Zhang, Can

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ZHANG-DISSERTATION-2018.pdf

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https://hdl.handle.net/2142/100886

Description

Title
Investigation of current-phase relation in topological insulator Josephson junction
Author(s)
Zhang, Can
Issue Date
2018-01-17
Director of Research (if dissertation) or Advisor (if thesis)
Van Harlingen, Dale
Doctoral Committee Chair(s)
Bezryadin, Alexey
Committee Member(s)
  • Vishveshwara, Smitha
  • Filippini, Jeffrey
Department of Study
Physics
Discipline
Physics
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Date of Ingest
2018-09-04T20:26:28Z
Keyword(s)
Topological Insulator Josephson Junction Majorana Fermion Majorana Bound states Superconductivity Current-Phase Relation
Abstract
In this thesis, we present current-phase relation (CPR) study of S-TI-S lateral Josephson junction (TIJJ). In a magnetic field, localized Majorana bound states (MBS) are predicted to exist at the core of Josephson vortices. One of the key characteristics of such MBS in TIJJ system is that they possess a 4π periodic CPR, instead of conventional 2π sinusoidal CPR. Our measurements of the critical current vs magnetic field modulation patterns have shown even-odd node-lifting effect in our TIJJ devices, which we interpret as evidence for a 4π-periodic sin(ϕ/2)-component in the Josephson CPR. This has motivated a model for the nucleation and manipulation of these MBS. We present a comprehensive study of a series of experiments designed to test in detail specific features of this model: (1) testing whether there is an even-odd pattern of node-lifting, (2) identifying irregular changes in the diffraction pattern that could indicate the abrupt entry of Majorana pairs, (3) searching for non-sinusoidal components in direct measurements of the CPR using an asymmetric SQUID technique.
Graduation Semester
2018-05
Type of Resource
text
Permalink
http://hdl.handle.net/2142/100886
Copyright and License Information
© 2017 by Can Zhang. All rights reserved.

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