Günel HY, Borgwardt N, Batov IE, Hardtdegen H, Sladek K, Panaitov G, Grützmacher D, Schäpers T. Crossover from Josephson effect to single interface Andreev reflection in asymmetric superconductor/nanowire junctions.
NANO LETTERS 2014;
14:4977-4981. [PMID:
25118624 DOI:
10.1021/nl501350v]
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Abstract
We report on the fabrication and characterization of symmetric nanowire-based Josephson junctions, that is, Al- and Nb-based junctions, and asymmetric junctions employing superconducting Al and Nb. In the symmetric junctions, a clear and pronounced Josephson supercurrent is observed. These samples also show clear signatures of subharmonic gap structures. At zero magnetic field, a Josephson coupling is found for the asymmetric Al/InAs-nanowire/Nb junctions as well. By applying a magnetic field above the critical field of Al or by raising the temperature above the critical temperature of Al the junction can be switched to an effective single-interface superconductor/nanowire structure. In this regime, a pronounced zero-bias conductance peak due to reflectionless tunneling has been observed.
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