Enhancement of the retrapping current of superconducting microbridges of finite length

Abstract

We theoretically find that the resistance of a superconducting microbridge/nanowire {\it decreases} while the retrapping current $I_r$ for the transition to the superconducting state {\it increases} when one suppresses the magnitude of the order parameter $|\Delta |$ in the attached superconducting leads. This effect is a consequence of the increased energy interval for diffusion of the 'hot' nonequilibrium quasiparticles (induced by the oscillations of $|\Delta |$ in the center of the microbridge) to the leads. The effect is absent in short microbridges (with length less than the coherence length) and it is relatively weak in long microbridges (with length larger than the inelastic relaxation length of the nonequilibrium distribution function). A nonmonotonous dependence of $I_r$ on the length of the microbridge is predicted. Our results are important for the explanation of the enhancement of the critical current and the appearance of negative magnetoresistance observed in many recent experiments on superconducting microbridges/nanowires.

6 pages, 7 figures

References in corpus (6)

• Magnetic field enhancement of superconductivity in ultra-narrow wires
• Quantum fluctuations in ultranarrow superconducting nanowires
• Negative magnetoresistance of ultra-narrow superconducting nanowires in the resistive state
• Negative magnetoresistance and phase slip process in superconducting nanowires
• Stabilizing Superconductivity in Nanowires by Coupling to Dissipative Environments
• Vortex instability in molybdenum-germanium superconducting films

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• Quantum magnetoresistive (hc/2e)/m periodic oscillations in a superconducting ring