Observation of domain wall motion in a polycrystalline vortex lattice

TL;DR

This study investigates how disorder influences vortex lattice dynamics in superconductors, revealing a two-step transition process and emphasizing the role of interface physics in disordered vortex systems.

Contribution

It provides experimental evidence of disorder-induced transitions in vortex lattices, highlighting the significance of polycrystalline structures and defect dynamics.

Findings

Two-step transition from pinned vortices to defect motion and then to bulk flow.

Disorder leads to polycrystalline vortex structures with defect formation at domain edges.

Disordered vortex systems favor interface physics over quasiperiodic regimes.

Abstract

We present measurements showing how disorder determines the dynamics of a vortex lattice. Using superconductor-normal-superconductor (SNS) arrays placed in finite magnetic fields, disorder is introduced by shifting the field away from values where the vortex lattice is commensurate with the SNS array. By applying a current to drive vortex motion, we observe a two-step transition at incommensurate fields: first from pinned vortices to lattice defect motion, and then from individual defect to bulk vortex lattice flow. This behavior is consistent with a polycrystalline vortex structure where defects form on the edges of crystalline domains. This demonstrates that a disordered, interacting vortex system can favor interface physics rather than a quasiperiodic regime.