Negative magnetoresistance and phase slip process in superconducting nanowires

TL;DR

This paper explains the negative magnetoresistance in superconducting nanowires by showing how magnetic fields influence the critical currents and phase slip processes, reducing resistance through suppression of phase slips.

Contribution

It introduces a mechanism where magnetic fields enhance critical currents and suppress phase slips, providing a new explanation for observed negative magnetoresistance in nanowires.

Findings

Magnetic fields can increase critical currents in nanowires.

Enhanced critical currents suppress phase slip rates.

Negative magnetoresistance is linked to reduced phase slip activity.

Abstract

We argue that the negative magnetoresistance of superconducting nanowires, which was observed in recent experiments, can be explained by the influence of the external magnetic field on the critical current of the phase slip process. We show that the suppression of the order parameter in the bulk superconductors made by an external magnetic field can lead to an enhancement of both the first $I_{c1}$ and the second $I_{c2}$ critical currents of the phase slip process in nanowires. Another mechanism of an enhancement of $I_{c1}$ can come from decreasing the decay length of the charge imbalance $\lambda_Q$ at weak magnetic fields because $I_{c1}$ is inversely proportional to $\lambda_Q$. The enhancement of the first critical current leads to a larger intrinsic dissipation of the phase slip process. It suppresses the rate of both the thermo-activated and/or quantum fluctuated phase slips and results in decreasing the fluctuated resistance.