Mode locking of vortex matter driven through mesoscopic channels

TL;DR

This study explores vortex dynamics in mesoscopic channels, revealing how mode-locking steps relate to lattice structure changes and pinning effects, supported by experimental and simulation data.

Contribution

It introduces a dc-rf interference technique to analyze vortex mode-locking and links lattice configurations to flow stress variations in mesoscopic channels.

Findings

Mode-locking steps indicate changes in vortex lattice structure.

Flow stress minima occur at coherent row motion.

Enhanced pinning is caused by edge dislocation fault zones.

Abstract

We investigated the driven dynamics of vortices confined to mesoscopic flow channels by means of a dc-rf interference technique. The observed mode-locking steps in the $IV$-curves provide detailed information on how the number of rows and lattice structure in the channel change with magnetic field. Minima in flow stress occur when an integer number of rows is moving coherently, while maxima appear when incoherent motion of mixed $n$ and $n\pm 1$ row configurations is predominant. Simulations show that the enhanced pinning at mismatch originates from quasi-static fault zones with misoriented edge dislocations induced by disorder in the channel edges.