Transverse depinning in weakly-pinned vortices

TL;DR

This study experimentally investigates the transverse depinning of vortices in weakly-pinned superconductors, revealing a significant transverse critical force influenced by longitudinal drive, with evidence of a first-order depinning transition.

Contribution

It demonstrates the existence of a large transverse critical depinning force in weakly-pinned vortices using crossed ac and dc currents, a novel experimental approach.

Findings

Transverse depinning force is greatly enhanced by longitudinal drive.

Transverse critical force exists across a large phase diagram region.

Hysteresis indicates a first-order depinning transition.

Abstract

We present experiments on weakly-pinned vortices, which exhibit a large critical transverse depinning force. These results are obtained in the superconducting metallic glasses Fe$_{x}$Ni$_{1-x}$Zr$_{2}$ using crossed ac and dc driving currents. We study the vortex depinning force due to the transverse ac drive as a function of a longitudinal dc drive; the ac/dc combination permits the separation of the transverse drive from the longitudinal one. We show that the force required for depinning in the transverse direction is greatly enhanced by the longitudinal drive, which demonstrates the existence of a large transverse critical force. The measurements are performed as a function of magnetic field and temperature and show that the transverse critical force exists in a large portion of the phase diagram. Hysteresis observed at the transverse depinning threshold is consistent with a first-order transverse depinning transition.