Visualization of Current-Driven Vortex Formation in High-$T_c$ Cuprate Superconductors

TL;DR

This study visualizes how current influences vortex formation in high-$T_c$ cuprate superconductors, revealing that current history affects vortex distribution and self-field effects, which impact measurements and phase transitions.

Contribution

It demonstrates that current-driven vortex nucleation and distribution can be directly imaged, highlighting the role of current history and self-field effects in high-$T_c$ superconductors.

Findings

Vortices nucleate even at zero magnetic field when cooled under current.

External magnetic fields polarize vortex distribution opposite to Lorentz force.

Current history influences vortex configuration and self-field effects.

Abstract

Type-II superconductors exhibit hysteretic behavior due to the presence of quantum vortices, and the order in which temperature and external field are varied plays a decisive role. Here we take current, rather than magnetic field, as the external drive. We image the magnetic field of a high-$T_c$ cuprate superconductor strip after cooling. We confirm that even in zero magnetic field, current-biased cooling nucleates vortices within the strip. With a small external magnetic field, the distribution is polarized opposite to the Lorentz-force direction. These behaviors follow from the self-consistent relation between current and local field in steady flux flow. Our findings show that current history is encoded as vortices. This reveals self-field effects that influence dc measurements and glassy transitions under drive.