Coherent and Incoherent Vortex Flow States in Crossed Channels

TL;DR

This paper investigates vortex flow behaviors in a specially designed pinning array with crossed channels, revealing coherent states at specific drive ratios that influence velocity responses and could apply to other particle systems.

Contribution

It introduces the concept of coherent vortex flow states in crossed channel geometries and links these states to velocity anomalies and negative differential conductivity.

Findings

Coherent flow states occur at rational drive ratios.

Velocity-force curves show anomalies linked to these states.

Negative differential conductivity observed in some conditions.

Abstract

We examine vortex flow states in periodic square pinning arrays with one row and one column of pinning sites removed to create an easy flow crossed channel geometry. When a drive is simultaneously applied along both major symmetry axes of the pinning array such that vortices move in both channels, a series of coherent flow states develop in the channel intersection at rational ratios of the drive components in each symmetry direction when the vortices can cross the intersection without local collisions. The coherent flow states are correlated with a series of anomalies in the velocity force curves, and in some cases can produce negative differential conductivity. The same general behavior could also be realized in other systems including colloids, particle traffic in microfluidic devices, or Wigner crystals in crossed one-dimensional channels.