Special Condensed Matter Seminar: Anil Murani, Laboratoire de Physique des Solides, Orsay, “Quantum interference of ballistic edge states in Bi-based Josephson junctions”

We have investigated proximity induced superconductivity in single crystal bismuth nanowires connected to superconducting electrodes with a high critical field. I will specially report recent results on nanowires whose crystalline orientation was determined by electron diffraction. At low temperature we find a supercurrent that persists up to the critical field of the electrodes, with sample-dependent, fast squid-like oscillations (period one to several hundred gauss) modulated by slower (few thousand-Gauss period) oscillations. Furthermore, we have measured the current-phase relation of the very same nanowire inserted in an asymmetric squid configuration up to very high magnetic field. We find that it shows sawtooth-shaped oscillations, indicative of ballistic transport with perfect Andreev reflection. We also observe 0-pi transitions and possibly phi junction behavior, which is a signature of the strong spin-orbit interaction in the nanowires.