Andreev reflection of helical edge modes in InAs/GaSb quantum spin Hall insulator

We present an experimental study of S-N-S junctions, with N being a quantum spin Hall insulator made of InAs/GaSb. A front gate is used to vary the Fermi level into the minigap, where helical edge modes exist [Phys. Rev. Lett. 107, 136603 (2011)]. In this regime we observe a ~2e(2)/h Andreev conduct...

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Bibliographic Details
Published in:Physical review letters 2012-11, Vol.109 (18), p.186603-186603, Article 186603
Main Authors: Knez, Ivan, Du, Rui-Rui, Sullivan, Gerard
Format: Article
Language:English
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Summary:We present an experimental study of S-N-S junctions, with N being a quantum spin Hall insulator made of InAs/GaSb. A front gate is used to vary the Fermi level into the minigap, where helical edge modes exist [Phys. Rev. Lett. 107, 136603 (2011)]. In this regime we observe a ~2e(2)/h Andreev conductance peak, consistent with a perfect Andreev reflection on the helical edge modes predicted by theories. The peak diminishes under a small applied magnetic field due to the breaking of time-reversal symmetry. This work thus demonstrates the helical property of the edge modes in a quantum spin Hall insulator.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.109.186603