Symmetry Protected Josephson Supercurrents in Three-Dimensional Topological Insulators

Coupling the surface state of a topological insulator (TI) to an s-wave superconductor is predicted to produce the long-sought Majorana quasiparticle excitations. However, superconductivity has not been measured in surface states when the bulk charge carriers are fully depleted, i.e., in the true to...

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Bibliographic Details
Published in:arXiv.org 2012-09
Main Authors: Cho, Sungjae, Dellabetta, Brian, Yang, Alina, Schneeloch, John, Xu, Zhijun, Valla, Tonica, Gu, Genda, Gilbert, Matthew J, Mason, Nadya
Format: Article
Language:English
Subjects:
Chemical potential
Current carriers
Organic chemistry
Quantum transport
Superconductivity
Superconductor junctions
Topological insulators
Topology
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Summary:Coupling the surface state of a topological insulator (TI) to an s-wave superconductor is predicted to produce the long-sought Majorana quasiparticle excitations. However, superconductivity has not been measured in surface states when the bulk charge carriers are fully depleted, i.e., in the true topological regime that is relevant for investigating Majorana modes. Here, we report measurements of DC Josephson effects in TI-superconductor junctions as the chemical potential is moved from the bulk bands into the band gap, or through the true topological regime characterized by the presence of only surface currents. We examine the relative behavior of the system at different bulk/surface ratios, determining the effects of strong bulk/surface mixing, disorder, and magnetic field. We compare our results to 3D quantum transport simulations to conclude that the supercurrent is largely carried by surface states, due to the inherent topology of the bands, and that it is robust against disorder.
ISSN:2331-8422
DOI:10.48550/arxiv.1209.5830