Fast moving superconducting vortices and determination of the critical current in high pulsed magnetic fields*

Expanding non-linear transport (I-V) studies to magnetic fields above those accessible by DC magnets can bring valuable information about systems such as superconductors, charge-density waves and topological semi-metals. All-superconducting very-high field magnets also make it technologically relevant to study vortex matter in this regime. However, pulsed magnetic fields reaching 100T in milliseconds impose technical and fundamental challenges that have prevented the realization of these studies. Here, we present a fast I-V DC technique that enables determination of the superconducting critical current in pulsed magnetic fields, beyond the reach of DC magnets. We demonstrate this technique on Cu- and Fe-based superconductors on single-crystalline and metallic substrates with excellent agreement with DC field measurements. The I-V characteristics change with the magnetic field rate (dH/dt). We capture this unexplored vortex physics through a model based on the broken symmetry of the vortex velocity profile produced by the applied current