# Novel dynamics and critical currents in fast superconducting vortices at high pulsed magnetic fields

## TL;DR

This paper introduces a novel high-speed measurement technique to study superconducting vortices at ultra-high pulsed magnetic fields, revealing new vortex dynamics influenced by the magnetic field rate of change.

## Contribution

It presents a sub-microsecond current-voltage measurement method enabling critical current determination in pulsed fields beyond DC magnet capabilities, and uncovers the impact of magnetic field rate on vortex behavior.

## Key findings

- Successful measurement of critical currents at 100 T pulsed fields.
- Discovery of the influence of magnetic field rate change ($dH/dt$) on vortex dynamics.
- Development of a theoretical model explaining vortex velocity asymmetry.

## Abstract

Non-linear electrical transport studies at high-pulsed magnetic fields, above the range accessible by DC magnets, are of direct fundamental relevance to the physics of superconductors, domain-wall, charge-density waves, and topological semi-metal. All-superconducting very-high field magnets also make it technologically relevant to study vortex matter in this regime. However, pulsed magnetic fields reaching 100 T in milliseconds impose technical and fundamental challenges that have prevented the realization of these studies. Here, we present a technique for sub-microsecond, smart, current-voltage measurements, which enables determining the superconducting critical current in pulsed magnetic fields, beyond the reach of any DC magnet. We demonstrate the excellent agreement of this technique with low DC field measurements on Y$_{0.77}$Gd$_{0.23}$Ba$_2$Cu$_3$O$_7$ coated conductors with and without BaHfO$_3$ nanoparticles. Exploring the uncharted high magnetic field region, we discover a characteristic influence of the magnetic field rate of change ($dH/dt$) on the current-voltage curves in a superconductor. We fully capture this unexplored vortex physics through a theoretical model based on the asymmetry of the vortex velocity profile produced by the applied current.