Electrically controlled crossover between 2 π and 4 π Josephson effects through topologically confined channels in silicene

We propose a tunable topological Josephson junction in silicene where electrostatic gates could switch between a trivial and a topological junction. These aspects are a consequence of a tunable phase transition of the topologically confined valley-chiral states from a spin-degenerate to a spin-helic...

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Bibliographic Details
Published in:Physical review. B 2018-11, Vol.98 (20), p.205305, Article 205305
Main Authors: Frombach, Daniel, Park, Sunghun, Schroer, Alexander, Recher, Patrik
Format: Article
Language:English
Subjects:
Crossovers
Josephson junctions
Mathematical models
Phase transitions
Quantum theory
Scattering
Silicene
Superconductor junctions
Superconductors
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Summary:We propose a tunable topological Josephson junction in silicene where electrostatic gates could switch between a trivial and a topological junction. These aspects are a consequence of a tunable phase transition of the topologically confined valley-chiral states from a spin-degenerate to a spin-helical regime. We calculate the Andreev bound states in such a junction analytically using a low-energy approximation to the tight-binding model of silicene in proximity to s-wave superconductors as well as numerically in the short- and long-junction regime and in the presence of intervalley scattering. Combining topologically trivial and nontrivial regions, we show how intervalley scattering can be effectively switched on and off within the Josephson junction. This constitutes a topological Josephson junction with an electrically tunable quasiparticle poisoning source.
ISSN:2469-9950
2469-9969
DOI:10.1103/PhysRevB.98.205305