Speaker
Description
We report switching-current signatures of magnetic avalanches in an $n$-doped InAs/Al nanowire Josephson junction. Under a perpendicular magnetic field, the device exhibits a low-field Fraunhofer-like modulation of the switching current together with reproducible discrete jumps appearing at $|B|\approx 3$~mT. These features separate distinct switching-current branches and show a clear sweep-history dependence.
By tracking the relevant field scales from 30 to 900~mK, we find that the jump field remains nearly temperature independent, in sharp contrast with the superconducting critical field, which follows the expected thermal suppression of Al. This distinction rules out conventional superconductivity-suppression mechanisms as the primary origin of the observed switching and instead points to a magnetically active subsystem coupled to the weak link.
We interpret the data in terms of avalanche-like reconfigurations of a metastable magnetic texture in the hybrid nanowire environment. Within an effective-field picture, each reconfiguration generates a discrete local-field offset that modifies the Josephson response and converts magnetic switching into abrupt transport discontinuities.
Our results identify hybrid nanowire Josephson junctions as sensitive probes of intrinsic magnetic dynamics at low magnetic fields and highlight their potential as mesoscopic hybrid platforms where superconducting transport directly reveals emergent magnetic degrees of freedom.
See arXiv:2603.29757 (2026)