Ph.D Defense Announcement by Xunchi Chen

Event Details
  • Date/Time:
    • Wednesday March 11, 2015
      2:00 pm - 4:00 pm
  • Location: Howey N110
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Summary Sentence: A Point Contact Spectroscopy Study of the Topological Superconductivity

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Title: A point contact spectroscopy study of the topological superconductivity

Author: Xunchi Chen

Date and Time: Wednesday, March 11th, 2015 at 2pm

Location: Howey N110

Committee:

Professor Zhigang Jiang,

Committee Chair (Advisor)

School of Physics

Georgia Institute of Technology

 

Professor Martin Mourigal

School of Physics

Georgia Institute of Technology

 

Professor Phillip First

School of Physics

Georgia Institute of Technology

 

Professor Jean Bellissard

School of Mathematics

Georgia Institute of Technology

 

Professor Andrew Zangwill

School of Physics

Georgia Institute of Technology


Abstract:

The study of topological superconductivity has been at the forefront of condensed matter physics for the past few years. Topological superconductors are predicted to have odd parity pairing and host the so called Majorana fermions, which is not only of fundamental importance, but also building block for fault-tolerant quantum computing. In this dissertation, we use point contact spectroscopy to study the pairing symmetry of candidate topological superconducting materials. We study the proximity induced superconductivity in topological insulator Bi2Se3 by a superconducting niobium tip, and propose a model to explain the features in the point contact spectra. We further study the nature of the superconductivity in highly doped superconducting topological insulators, including CuxBi2Se3 and Sn(1-x)InxTe, using both normal metal gold tip and superconducting niobium tip. For CuxBi2Se3, we observe robust zero-bias conductance peak (ZBCP) in the differential conductance spectra with gold point contact, while with niobium point contact we find the height of the peak exhibiting an unusual non-monotonic temperature dependence. We argue that both observations cannot be explained by Andreev reflection within the standard Blonder, Tinkham, Klapwijk (BTK) model, but signifying unconventional superconductivity in the material. For Sn(1-x)InxTe samples, we observe ZBCP in the differential conductance spectra with gold point contact, while with niobium point contact, the temperature dependence of ZBCP is monotonic as expected from conventional theory, leaving the nature of the superconductivity of Sn(1-x)InxTe still an open question.

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graduate students, PhD Dissertation Defense
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  • Created By: Tatianna Richardson
  • Workflow Status: Published
  • Created On: Feb 20, 2015 - 7:36am
  • Last Updated: Oct 7, 2016 - 9:47pm