Magnetic field enhanced critical current and subharmonic structures in dissipative superconducting gold nanowires

Quantum breakdown of superconductivity in low-dimensional superconducting systems has attracted enormous attention due to the underlying fluctuation. Here we report exotic phenomena observed during the current-induced breakdown of superconductivity in gold nanowires contacted by superconducting electrodes. In a 1.0 μ m-long nanowire, the resistance as a function of current exhibits a random resistance switching at 1.8 K and tail-like metallic state at higher temperatures, indicating phase slips in proximity-induced superconducting nanowire. Additionally, the upper critical current is enhanced under low magnetic field, which may be attributed to the formation of spin-triplet pairing in superconducting gold nanowire. In a 1.2 μ m-long gold nanowire, unexpected subharmonic structures with characteristic energy smaller than superconducting gap are superimposed on tail-like structures. The signal might be related to the axions-triggered process in phase slip center Josephson junction and thus stimulate further studies in dissipative superconducting nanowires.