Quantum phase slip phenomenon in superconducting nanowires with low-Ohmic environment

TL;DR

This paper investigates the quantum phase slip phenomenon in ultra-thin superconducting nanowires under low-Ohmic conditions, revealing resistance behavior inconsistent with traditional models and observing negative magnetoresistance at low temperatures.

Contribution

It explores the regime of strong quantum fluctuations in superconducting nanowires where existing models fail, providing new insights into resistance behavior and magnetoresistance effects.

Findings

Resistance remains finite below critical temperature despite low currents

Negative magnetoresistance observed at low temperatures

Existing models do not explain the strong quantum fluctuation regime

Abstract

In a number of recent experiments it has been demonstrated that in ultra-narrow superconducting channels quantum fluctuations of the order parameter, alternatively called quantum phase slips, are responsible for the finite resistance well below the critical temperature. The acceptable agreement between those experiments and the models describing quantum fluctuations in quasi-one-dimensional superconductors has been established. However the very concept of the phase slip is justified when these fluctuations are the relatively rare events, meaning that the effective resistance of the system should be much smaller than the normal state equivalent. In this paper we study the limit of the strong quantum fluctuations where the existing models are not applicable. In particular case of ultra-thin titanium nanowires it is demonstrated that below the expected critical temperature the resistance does not demonstrate any trend towards the conventional for a superconductor zero-resistivity state even at negligibly small measuring currents. Application of a small magnetic field leads to an unusual negative magnetoresistance, which becomes more pronounced at lower temperatures. The origin of the negative magnetoresistance effect is not clear.