Inherent stochasticity of superconductive-resistive switching in nanowires

TL;DR

This paper investigates the stochastic nature of superconductive-resistive switching in nanowires, proposing a model that explains how single phase-slip events can induce switching and how the distribution of switching currents varies with temperature.

Contribution

It introduces a stochastic temperature evolution model for nanowires, revealing conditions under which single phase-slip events cause switching and describing temperature-dependent distribution behaviors.

Findings

Single phase-slip events can induce switching at certain conditions.

Distribution of switching currents broadens at lower temperatures.

At lower temperatures, the distribution narrows as expected for thermally activated phase slips.

Abstract

Hysteresis in the current-voltage characteristic in a superconducting nanowire reflects an underlying bistability. As the current is ramped up repeatedly, the state switches from a superconductive to a resistive one, doing so at random current values below the equilibrium critical current. Can a single phase-slip event somewhere along the wire--during which the order-parameter fluctuates to zero--induce such switching, via the local heating it causes? We address this and related issues by constructing a stochastic model for the time-evolution of the temperature in a nanowire whose ends are maintained at a fixed temperature. The model indicates that although, in general, several phase-slip events are necessary to induce switching, there is indeed a temperature- and current-range for which a single event is sufficient. It also indicates that the statistical distribution of switching currents initially broadens, as the temperature is reduced. Only at lower temperatures does this distribution show the narrowing with cooling naively expected for resistive fluctuations consisting of phase slips that are thermally activated.