Phase slips in superconducting films with constrictions

TL;DR

This paper investigates phase slips in superconducting films with constrictions, revealing two resistive transitions related to BKT behavior and thermally activated phase slips, and provides a method to measure resistance over a broad range.

Contribution

It introduces an indirect measurement technique for resistance and characterizes the resistance behavior of superconducting bridges over eleven orders of magnitude.

Findings

Resistive transitions linked to BKT and phase slip phenomena.

Resistance follows a universal exponential relation.

Method enables resistance measurement over eleven orders of magnitude.

Abstract

A system of two coplanar superconducting films seamlessly connected by a bridge is studied. We observe two distinct resistive transitions as the temperature is reduced. The first one, occurring in the films, shows some properties of the Berezinskii-Kosterlitz-Thouless (BKT) transition. The second apparent transition (which is in fact a crossover) is related to freezing out of thermally activated phase slips (TAPS) localized on the bridge. We also propose a powerful indirect experimental method allowing an extraction of the sample's zero-bias resistance from high-current-bias measurements. Using direct and indirect measurements, we determined the resistance $R(T)$ of the bridges within a range of {\em eleven orders of magnitude}. Over such broad range, the resistance follows a simple relation $R(T)=R_N \text{exp} [-(c/t)(1-t)^{3/2}]$, where $c=\Delta F(0) / kT_c$ is the normalized free energy of a phase slip at zero temperature, $t=T/T_c$ is normalized temperature, and $R_N$ is the normal resistance of the bridge.