Giant Magnetoconductance Oscillations in Hybrid Superconductor-Semiconductor Core/Shell Nanowire Devices

The magnetotransport of GaAs/InAs core/shell nanowires contacted by two superconducting Nb electrodes is investigated, where the InAs shell forms a tube-like conductive channel around the highly resistive GaAs core. By applying a magnetic field along the nanowire axis, regular magnetoconductance oscillations with an amplitude in the order of e(2)/h are observed. The oscillation amplitude is found to be larger by 2 orders of magnitude compared to the measurements of a reference sample with normal metal contacts. For the Nb-contacted core/shell nanowire the oscillation period corresponds to half a flux quantum Phi(0)/2 = h/2e in contrast to the period of Phi(0) of the reference sample. The strongly enhanced magnetoconductance oscillations are explained by phase-coherent resonant Andreev reflections at the Nb-core/shell nanowire interface.