Disordering, clustering, and laning transitions in particle systems with dispersion in the Magnus term

Abstract

We numerically examine a two-dimensional system of repulsively interacting particles with dynamics that are governed by both a damping term and a Magnus term. The magnitude of the Magnus term has one value for half of the particles and a different value for the other half of the particles. In the absence of a driving force, the particles form a triangular lattice, while when a driving force is applied, we find that there is a critical drive above which a Magnus-induced disordering transition can occur even if the difference in the Magnus term between the two particle species is as small as one percent. The transition arises due to the different Hall angles of the two species, which causes their motion to decouple at the critical drive. At higher drives, the disordered state can undergo both species and density phase separation into a density modulated stripe that is oriented perpendicular to the driving direction. We observe several additional phases that occur as a function of drive and Magnus force disparity, including a variety of density modulated diagonal laned phases. In general we find a much richer variety of states compared to systems of oppositely driven overdamped Yukawa particles. We discuss the implications of our work for skyrmion systems, where we predict that even for small skyrmion dispersities, a drive-induced disordering transition can occur along with clustering phases and pattern forming states.

Emergent collective colloidal currents generated via exchange dynamics in a broken dimer state

“…The exotic states we report here via an engineered soft-shoulder potential were predicted in different theoretical models, but not observed so far (13,15). We note that similar dynamic states with particles sliding in opposite directions have been recently observed in a numerical simulation of bidisperse spinning particles with a dispersion in the Magnus term (22).…”

Traveling band formation in feedback-driven colloids

“…1(a) spontaneously separates into two regions which are either empty or crowded (i.e., exhibiting a high density of particles). This demixed state coarsens further as a function of time into a configuration of system-spanning straight bands at long times, resembling those observed in mixtures of particles subjected to bidisperse Magnus forces [90]. The width of the formed bands depends on the specific parameters of the particle repulsion and the feedback potential as well as the delay time τ .…”

Late stages in the ordering of magnetic skyrmion lattices

“…For example, in driven systems a constant angle, known as the skyrmion Hall angle, appears between the direction of the drive and the direction of displacement 7,[13][14][15][16][17][18][19] . Other studies have focused on the appearance of avalanches when the driven skyrmions interact with random pins 20 , the pattern formation of geometrically confined skyrmions 21 , the existence of nonequilibrium phase transitions between different dynamic phases 22,23 , shear banding of driven skyrmions in inhomogeneous pinning arrays 24 , laning transitions in presence of damping 25 , as well as the formation of skyrmion crystals 26,27 and the flow of skyrmion lattices 28 .…”