Josephson Interference due to Orbital States in Nanowire Proximity Effect Junctions

Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada(Dated: June 23, 2014)The Josephson supercurrent in a Nb-InAs nanowire-Nb junction was studied experimentally. Thenanowire goes superconducting due to the proximity e ect, and can sustain a phase coherent su-percurrent. An unexpected modulation of the junction critical current in an axial magnetic eldis observed, which we attribute to a novel form of Josephson interference, due to the multi-bandnature of the nanowire. Andreev pairs occupying states of di erent orbital angular momentumacquire di erent superconducting phases, producing oscillations of the critical current versus mag-netic ux. We develop a semi-classical multi-band model that reproduces the experimental datawell. While spin-orbit and Zeeman e ects are predicted to produce similar behaviour, the orbitale ects are dominant in the device studied here. This interplay between orbital states and magnetic eld should be accounted for in the study of multi-band nanowire Josephson junctions, in particular,regarding the search for signatures of topological superconductivity in such devices.