Simulating the dynamics of liquid-crystal skyrmions*

In magnetic systems, extensive research has investigated skyrmion motion, which is achieved by small electric currents. Similarly, in liquid crystals, recent experiments demonstrate that skyrmions can be moved by fluid flow, light, and electric fields [1]. Here, we use analytic and numerical methods, including Monte Carlo and relaxational dynamics simulations, to model the particle-like motion and interaction of liquid crystal skyrmions. First, we determine the effect of electric field changes on skyrmion shape, and demonstrate that field gradients can induce skyrmion motion. Next, we consider the exposure of certain liquid crystals to light which changes the helical pitch. To model the effect of such pitch changes, we apply gradients in the natural twist and find that these gradients also induce skyrmion motion. These results regarding electric fields and light are in qualitative agreement with experiments. Finally, we show that nonuniform surface anchoring can also be used to manipulate skyrmion motion, and we investigate the elasticity of skyrmions subjected to force.

[1] P. J. Ackerman, T. Boyle, and I. I. Smalyukh. Squirming motion of baby skyrmions in nematic fluids. Nat. Commun. 8, 673 (2017).