Particle-based model of active skyrmions

TL;DR

This paper introduces a particle-based model for active liquid crystal skyrmions that captures their collective dynamics and velocity behaviors under electric field modulation, based on continuum theory and experimental insights.

Contribution

The authors develop a coarse-grained particle model that accurately reproduces skyrmion dynamics, including velocity reversal, by mapping director distortions to effective forces from continuum theory.

Findings

Model reproduces skyrmion velocity reversal.

Analytical expressions relate model parameters to physical properties.

Model aligns with continuum Frank-Oseen approach results.

Abstract

Motivated by recent experimental results that reveal rich collective dynamics of thousands-to-millions of active liquid crystal skyrmions we have developed a coarse grained particle-based model of the dynamics of skyrmions in dilute regime. The basic physical mechanism of the skyrmion motion is related to the non-reciprocal rotational dynamics of the liquid crystal director field when the electric field is turned {\it on} and {\it off}. Guided by fine grained results of the Frank-Oseen continuum approach, we have mapped this non-reciprocal director distortions onto an effective force acting asymmetrically upon switching the electrical field {\it on} or {\it off}. The coarse grained model correctly reproduces the skyrmion dynamics, including the velocity reversal as a function of the frequency of a pulse width modulated driving voltage. We have also obtained approximate analytical expressions for the phenomenological model parameters encoding their dependence upon the cholesteric pitch and the strength of the electric field. This has been achieved by fitting coarse grained skyrmion trajectories to those determined in the framework of the Frank-Oseen model.