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Title: Phase coherence and Andreev reflection in topological insulator devices

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 show that TIs are a promising platform for exploring phase-coherent transport in a solid-state system.
 [1] ;  [1] ;  [2] ;  [1]
  1. University of Illinois at Urbana-Champaign, Urbana, IL (United States)
  2. Missouri Univ. of Science and Technology, Rolla, MO (United States)
Publication Date:
Grant/Contract Number:
DMR-12-55607; FG02-07ER46453; FG02-07ER46471
Accepted Manuscript
Journal Name:
Physical Review. X
Additional Journal Information:
Journal Volume: 4; Journal Issue: 4; Journal ID: ISSN 2160-3308
American Physical Society
Research Org:
University of Illinois at Urbana-Champaign, Urbana, IL (United States)
Sponsoring Org:
Country of Publication:
United States
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; condensed matter physics; superconductivity; topological insulators
OSTI Identifier: