Proximity-Induced π Josephson Junctions in Topological Insulators and Kramers Pairs of Majorana Fermions

We study two microscopic models of topological insulators in contact with an s-wave superconductor. In the first model the superconductor and the topological insulator are tunnel coupled via a layer of randomly distributed scalar and of randomly oriented spin impurities. Here, we demonstrate that sp...

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Bibliographic Details
Published in:Physical review letters 2015-12, Vol.115 (23), p.237001-237001, Article 237001
Main Authors: Schrade, Constantin, Zyuzin, A A, Klinovaja, Jelena, Loss, Daniel
Format: Article
Language:English
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Summary:We study two microscopic models of topological insulators in contact with an s-wave superconductor. In the first model the superconductor and the topological insulator are tunnel coupled via a layer of randomly distributed scalar and of randomly oriented spin impurities. Here, we demonstrate that spin-flip tunneling dominates over the spin-conserving one. In the second model the tunnel coupling is realized by a spatially nonuniform array of single-level quantum dots with randomly oriented spins. We find that the tunnel region forms a π junction where the effective order parameter changes sign. Because of the random spin orientation, effectively both models exhibit time-reversal symmetry. The proposed π junctions support topological superconductivity without magnetic fields and can be used to generate and manipulate Kramers pairs of Majorana fermions by gates.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.115.237001