Magnetic-Field-Induced Stabilization of Non-Equilibrium Superconductivity

TL;DR

This paper demonstrates that applying a small magnetic field can stabilize non-equilibrium superconductivity by enhancing quasiparticle relaxation, leading to improved cooling in superconductor-based devices.

Contribution

It reveals that a modest magnetic field enhances quasiparticle relaxation in superconductors, stabilizing non-equilibrium states and improving device cooling performance.

Findings

Magnetic field of ~100 μT improves quasiparticle relaxation.

Enhanced QP drain occurs via vortices in S leads.

Cooling of N island is significantly improved.

Abstract

A small magnetic field is found to enhance relaxation processes in a superconductor thus stabilizing superconductivity in non-equilibrium conditions. In a normal-metal (N) - insulator - superconductor (S) tunnel junction, applying a field of the order of 100 \mu T leads to significantly improved cooling of the N island by quasiparticle (QP) tunneling. These findings are attributed to faster QP relaxation within the S electrodes as a result of enhanced QP drain through regions with locally suppressed energy gap due to magnetic vortices in the S leads at some distance from the junction.