Insulating, metallic and superconducting behavior in a single nanowire

TL;DR

This study investigates the electronic behavior of superconducting nanowires in the quantum phase slip regime, revealing a transition from insulating to metallic to superconducting states, with a novel in situ resistance tuning method applicable at various temperatures.

Contribution

We developed an intrinsic electromigration technique to precisely lower nanowire resistance in situ, enabling detailed study of quantum phase slip phenomena across different regimes.

Findings

Observation of Coulomb blockade and critical currents depending on resistance

Identification of a continuous transition with nonlinear metallic-like behavior

Resistance change spans over three orders of magnitude at room temperature

Abstract

In systems with reduced dimensions quantum fluctuations have a strong influence on the electronic conduction, even at very low temperature. In superconductors this is especially interesting, since the coherent state of the superconducting electrons is strongly interacting with these fluctuations and therefore is a sensitive tool to study them. In this paper, we report on comprehensive measurements of superconducting nanowires in the quantum phase slip regime. Using an intrinsic electromigration process, we have developed a method to lower the resistance of lithographically fabricated highly resistive nanowires in situ and in small consecutive steps. At low temperature we observe critical (Coulomb) blockade voltages and superconducting critical currents, depending on the nanowire's normal-state resistance, in good agreement with theoretical models. Between these two regimes, we find a continuous transition displaying a nonlinear metallic-like behavior. The reported intrinsic electromigration technique is not limited to low temperatures as we find a similar change in resistance that spans over three orders of magnitude also at room temperature. Aside from superconducting quantum circuits, such a technique to reduce the resistance may also have applications in modern electronic circuits.