The absence of Fraunhofer patterns in narrow Nb/InAs-nanowire/Nb junctions

We used InAs nanowires with two different charge carrier concentration to fabricate Josephson junctions with superconducting Nb electrodes. For highly doped nanowire junctions a supercurrent is observed up to T ∼ 5 K, for low doped nanowire junctions we were able to tune the Josephson current by a back gate voltage. Owing to the transparent interface between Nb and InAs nanowires subharmonic gap structures due to multiple Andreev reflection have been observed. Furthermore, the effect of magnetic field on the Josephson current was investigated and a monotonous decrease of Josephson current was found. The observed behavior has been compared with a theoretical model.