Supercurrent in Nb/InAs-nanowire/Nb Josephson junctions

Günel, H.Y.; Sladek, K.; Schäpers, Th.; Hardtdegen, H.; Batov, I.E.; Grützmacher, D.; Panaitov, G.; Weis, K.; Winden, A.

doi:10.1063/1.4745024

Journal Article

Supercurrent in Nb/InAs-nanowire/Nb Josephson junctions

Günel, H. Y.FZJ* ; Batov, I. E. ; Hardtdegen, H. ; Sladek, K. ; Winden, A.FZJ* ; Weis, K.FZJ* ; Panaitov, G.FZJ* ; Grützmacher, D.FZJ* ; Schäpers, T.FZJ*

2012
American Institute of Physics Melville, NY

Journal of applied physics 112, 034316 (2012) [10.1063/1.4745024]

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Please use a persistent id in citations: http://hdl.handle.net/2128/7575 doi:10.1063/1.4745024

Abstract: We report on the fabrication and measurements of planar mesoscopic Josephson junctions formed by InAs nanowires coupled to superconducting Nb terminals. The use of Si-doped InAs-nanowires with different bulk carrier concentrations allowed to tune the properties of the junctions. We have studied the junction characteristics as a function of temperature, gate voltage, and magnetic field. For junctions with high doping concentrations in the nanowire, Josephson supercurrent values up to 100 nA are found. Owing to the use of Nb as superconductor, the Josephson coupling persists at temperatures up to 4 K. In all junctions, the critical current monotonously decreased with the magnetic field, which can be explained by a recently developed theoretical model for the proximity effect in ultra-small Josephson junctions. For the low-doped Josephson junctions, a control of the critical current by varying the gate voltage has been demonstrated. We have studied conductance fluctuations in nanowires coupled to superconducting and normal metal terminals. The conductance fluctuation amplitude is found to be about 6 times larger in superconducting contacted nanowires. The enhancement of the conductance fluctuations is attributed to phase-coherent Andreev reflection as well as to the large number of phase-coherent channels due to the large superconducting gap of the Nb electrodes. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4745024]

Keyword(s): J

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Physics, Applied

Note: The authors are grateful to H. Kertz for assistance during the measurements and S. Trellenkamp for electron beam writing. H.Y.G. thanks The Scientific and Technological Research Council of Turkey (TUBITAK) foundation. I.E.B. acknowledges the Russian Foundation for Basic Research, Project No. RFBR 09-02-01499 for financial support.

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