Phase coherence and andreev reflection in topological insulator devices

A. D.K. Finck, C. Kurter, Y. S. Hor, D. J. Van Harlingen

Research output: Contribution to journalArticle

Abstract

Topological insulators (TIs) have attracted immense interest because they host helical surface states. Protected by time-reversal symmetry, they are robust to nonmagnetic disorder. When superconductivity is induced in these helical states, they are predicted to emulate p-wave pairing symmetry, with Majorana states bound to vortices. Majorana bound states possess non-Abelian exchange statistics that can be probed through interferometry. Here, we take a significant step towards Majorana interferometry by observing pronounced Fabry-Pérot oscillations in a TI sandwiched between a superconducting and a normal lead. For energies below the superconducting gap, we observe a doubling in the frequency of the oscillations, arising from an additional phase from Andreev reflection. When a magnetic field is applied perpendicular to the TI surface, a number of very sharp and gate-tunable conductance peaks appear at or near zero energy, which has consequences for interpreting spectroscopic probes of Majorana fermions. Our results demonstrate that TIs are a promising platform for exploring phase-coherent transport in a solid-state system.

Original languageEnglish (US)
Article number041022
JournalPhysical Review X
Volume4
Issue number4
DOIs
StatePublished - Jan 1 2014

Keywords

  • Condensed matter physics
  • Superconductivity
  • Topological insulators

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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