Interaction of the Torque-Induced Elastic Charge and Elastic Dipole with a Wall in a Nematic Liquid Crystal

TL;DR

This paper explores how external torque can generate elastic charges in colloids within nematic liquid crystals, affecting their interactions with walls and inducing switchable force behaviors.

Contribution

It introduces a novel theory linking external torque to elastic charge generation and demonstrates its impact on colloid-wall interactions in nematic liquid crystals.

Findings

External torque induces elastic charge in colloids.

Wall interactions can switch from 1/r^4 to 1/r^2 force.

Elastic charge affects colloid dynamics near surfaces.

Abstract

We show that the elastic charge of colloids in a nematic liquid crystal can be generated by the vector of external torque. The torque components play the role of two component charge (dyad) and give rise to the Coulomb-like potential, while their conservation law plays the role similar to that of Gauss' theorem in the electrostatics. The theory is applied to the colloid-surface interaction. A wall with homeotropic or planar director is shown to induce a repulsive 1/r^4 force on the elastic dipole. The external torque, however, induces the elastic charge in this colloid and triggers switching to the 1/r^2 repulsion.