Equilibrium and Driven Vortex Phases in the Anomalous Peak Effect

TL;DR

This study experimentally investigates the peak effect in weakly disordered type-II superconductors, revealing it results from a crossover involving vortex phase defects and showing dimensional differences in vortex dynamics.

Contribution

It provides experimental evidence supporting a vortex phase crossover model for the peak effect and highlights the role of dislocations and dimensionality in vortex lattice behavior.

Findings

Peak effect arises from a crossover between Larkin length and elastic length.

Both screw and edge dislocations are involved in vortex lattice disordering.

Driven vortex dynamics differ significantly between 2D and 3D samples.

Abstract

We report a crucial experimental test of the present models of the peak effect in weakly disordered type-II superconductors. Our results favor the scenario in which the peak effect arises from a crossover between the Larkin pinning length and a rapidly falling elastic length in a vortex phase populated with thermally excited topological defects. A thickness dependence study of the onset of the peak effect at varying driving currents suggests that both screw and edge dislocations are involved in the vortex lattice disordering. The driven dynamics in 3D samples are drastically different from those in 2D samples. We suggest that this may be a consequence of the absence of a Peierls potential for screw dislocations in a vortex line lattice.