Magnetically Induced Switching-Current Jumps in InAs/Al Josephson Junctions

TL;DR

This study observes magnetically induced switching-current jumps in InAs/Al Josephson junctions, revealing magnetic reconfigurations that cause abrupt changes in supercurrent, with potential implications for understanding magnetic textures in superconducting devices.

Contribution

It demonstrates magnetic reconfigurations causing discrete switching-current jumps in InAs/Al Josephson junctions, providing insight into magnetic textures affecting supercurrent behavior.

Findings

Discontinuous switching-current jumps occur at millitesla fields.

The jump field remains temperature-independent from 30 mK to 900 mK.

Switching behavior is linked to magnetic reconfigurations of the local magnetic texture.

Abstract

We report Barkhausen-like switching at millitesla fields in an $n$-doped InAs/Al nanowire Josephson junction, which serves as an interferometric probe of intrinsic magnetic reconfigurations, as evidenced by discrete switching-current jumps. At $T=30$~mK the device displays a Fraunhofer-like modulation with $I_{\mathrm{sw}}(0)\approx 0.24~\mu\mathrm{A}$ and an abrupt transition at $|B|\approx 3~\mathrm{mT}$ between two branches differing by $\Delta I_{\mathrm{sw}}\approx 0.13~\mu\mathrm{A}$. By tracking the characteristic field scales from $30$ to $900$~mK, we find that the jump field is essentially temperature-independent, whereas the superconducting critical field decreases with temperature, as expected for thin Al films. The sharp discontinuity, sweep-direction asymmetry, and reproducibility across repeated scans point to avalanche-like switching between metastable magnetic configurations of the local magnetic texture, which are directly coupled to the weak link. Within an effective-field framework, each reconfiguration modifies a local field offset, thereby reshaping the interference response and leading to an abrupt reorganization of the switching-current pattern.