Vortex Guidance and Transport in Channeled Pinning Arrays

TL;DR

This study uses numerical simulations to explore how vortices move through channeled pinning arrays with mixed strong and weak pinning regions, revealing complex flow behaviors depending on drive direction and vortex density.

Contribution

It introduces a detailed analysis of vortex dynamics in channeled pinning arrays with partial pin removal, highlighting novel flow phases and reentrant pinning effects.

Findings

Distinct vortex flow regimes depending on drive direction

Identification of a jammed phase at certain drives

Drive-induced reentrant pinning and negative differential mobility

Abstract

We numerically examine vortices interacting with pinning arrays where a portion of the pinning sites have been removed in order to create coexisting regions of strong and weak pinning. The region without pinning sites acts as an easy-flow channel. For driving in different directions with respect to the channel, we observe distinct types of vortex flow. When the drive is parallel to the channel, the flow first occurs in the pin free region followed by a secondary depinning transition in the pinned region. At high vortex densities there is also an intermediate plastic flow phase due to the coupling between the weak and strong pinning regions. For driving applied perpendicular to the channel, we observe a jammed phase in which vortices accumulate on the boundary of the pinned region due to the vortex-vortex repulsion, while at higher drives the vortices begin to flow through the pinning array. For driving at an angle to the channel, depending on the filling we observe a drive-induced reentrant pinning effect as well as negative differential mobility which occurs when vortices move from the unpinned to the pinned portion of the sample.