Superconducting bistability in floating Al islands of hybrid Al/InAs nanowires

TL;DR

This paper explores the non-equilibrium superconducting-normal phase transition in floating Al islands on InAs nanowires, revealing hysteresis, voltage jumps, and the failure of traditional models, with implications for hybrid superconducting devices.

Contribution

It uncovers non-equilibrium effects and hysteretic behavior in superconducting islands, challenging existing two-temperature models in hybrid nanowire systems.

Findings

Discontinuous voltage jumps and hysteresis observed in I-V characteristics.

Behavior varies across devices and can be suppressed by magnetic fields.

Numerical models show non-equilibrium corrections explain the phenomena.

Abstract

We investigate a non-equilibrium aspect of the current-driven superconducting-normal phase transition in floating Al islands of epitaxial full-shell Al/InAs nanowires. Within a transition region discontinuous voltage jumps and hysteretic behaviour of the I-V characteristics are observed, associated with the destruction and recovery of the superconducting order parameter in the island. The strength of the two features varies strongly in different devices in a mutually correlated way and can be suppressed by a small magnetic field. Numerical calculation explains this behaviour in terms of a tiny non-equilibrium correction to the electronic energy distribution at low energies. The experiment demonstrates a critical failure of a two-temperature non-equilibrium model of the superconductor-normal transition in floating islands of hybrid nanowire devices.