Investigation of current-phase relation in topological insulator Josephson junction

Zhang, Can

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

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

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

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

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© 2017 by Can Zhang. All rights reserved.

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