Laminar and transiently disordered dynamics of a magnetic skyrmion pipe flow

TL;DR

This paper investigates the complex laminar and disordered flow behaviors of magnetic skyrmions in a pipe channel, revealing how current and magnetic anisotropy influence their structural transitions and flow dynamics.

Contribution

It provides the first detailed analysis of skyrmion flow behaviors in a pipe channel, including structural transitions and effects of magnetic anisotropy, highlighting their fluid-like properties.

Findings

Skyrmion flow can transition from laminar to disordered states.

Current-driven compression causes skyrmions to form open-channel flows.

Magnetic anisotropy variations lead to complex flow dynamics.

Abstract

The world is full of fluids that flow. The fluid nature of flowing skyrmionic quasiparticles is of fundamental physical interest and plays an essential role in the transport of many skyrmions. Here, we report the laminar and transiently disordered dynamic behaviors of many magnetic skyrmions flowing in a pipe channel. The skyrmion flow driven by a uniform current may show a lattice structural transition. The skyrmion flow driven by a non-uniform current shows a dynamically varying lattice structure. A large uniform current could result in the compression of skyrmions toward the channel edge, leading to the transition of the skyrmion pipe flow into an open-channel flow with a free surface. Namely, the width of the skyrmion flow could be adjusted by the driving current. Skyrmions on the free surface may form a single shear layer adjacent to the main skyrmion flow. In addition, although we focus on the skyrmion flow dynamics in a clean pipe channel without any pinning or defect effect, we also show that a variation of magnetic anisotropy in the pipe channel could lead to more complicated skyrmion flow dynamics and pathlines. Our results reveal the fluid nature of skyrmionic quasiparticles that may motivate future research on the complex flow physics of magnetic textures.