Coarse-grained theory for motion of solitons and skyrmions in liquid crystals

Recent experiments have found that applied electric fields can induce motion of skyrmions in chiral nematic liquid crystals. To understand the magnitude and direction of the induced motion, we develop a coarse-grained approach to describe dynamics of skyrmions, similar to our group's previous w...

Full description

Saved in:
Bibliographic Details
Published in:Soft matter 2021-12, Vol.17 (46), p.1437-1446
Main Authors: Long, Cheng, Selinger, Jonathan V
Format: Article
Language:English
Subjects:
Cholesteric liquid crystals
Crystals
Disclinations
Electric fields
Equations of motion
Excitation
Hypothetical particles
Nematic crystals
Particle theory
Solitary waves
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Recent experiments have found that applied electric fields can induce motion of skyrmions in chiral nematic liquid crystals. To understand the magnitude and direction of the induced motion, we develop a coarse-grained approach to describe dynamics of skyrmions, similar to our group's previous work on the dynamics of disclinations. In this approach, we represent a localized excitation in terms of a few macroscopic degrees of freedom, including the position of the excitation and the orientation of the background director. We then derive the Rayleigh dissipation function, and hence the equations of motion, in terms of these macroscopic variables. We demonstrate this theoretical approach for 1D motion of a sine-Gordon soliton, and then extend it to 2D motion of a skyrmion. Our results show that skyrmions move in a direction perpendicular to the induced tilt of the background director. When the applied field is removed, skyrmions move in the opposite direction but not with equal magnitude, and hence the overall motion may be rectified. A coarse-grained theory is developed to characterize the motion of topological structures in nematic liquid crystals under the effect of a changing external field, and the mechanism of the squirming motion for a skyrmion is elucidated.
ISSN:1744-683X
1744-6848
DOI:10.1039/d1sm01335a