Two superconducting transitions and periodic magnetoresistance oscillations in the crystalline Au nanowire with superconducting electrodes

Transport measurements were made on individual crystalline Au nanowire with four focused ion beam (FIB) deposited tungsten (W) electrodes, which are superconducting below 5 K. It was found that the 1.2 microns long (between the inner edges of the two voltage electrodes) Au nanowire is superconducting. Instead of a single sharp drop to zero resistance as seen in usual superconductors, here the resistance drops in two steps. Below TC, with a magnetic field applied perpendicular to the axis of the nanowire, we found ``magnetoresistance mini-gaps'' in low field regime. In addition, clear periodic magnetoresistance oscillations in the superconducting to normal transition region were observed. The 1 micron and 1.9 microns Au nanowires were also investigated to further reveal the anomalous superconductivity we found.