Self-Assembly and Nonlinear Dynamics of Dimeric Colloidal Rotors in Cholesterics

TL;DR

This paper investigates the self-assembly and nonlinear rotational dynamics of colloidal dimers in cholesteric liquid crystals through simulations, revealing force-induced rotation behaviors and phase transitions.

Contribution

It introduces a simulation study of colloidal dimer behavior in cholesterics, highlighting their assembly and complex rotational dynamics under external forces.

Findings

Colloidal pairs attract and form dimers at specific orientations.

Dimer rotation exhibits continuous or stepwise phase-slip dynamics.

A sharp transition separates different rotational regimes.

Abstract

We study by simulation the physics of two colloidal particles in a cholesteric liquid crystal with tangential order parameter alignment at the particle surface. The effective force between the pair is attractive at short range and favors assembly of colloid dimers at specific orientations relative to the local director field. When pulled through the fluid by a constant force along the helical axis, we find that such a dimer rotates, either continuously or stepwise with phase-slip events. These cases are separated by a sharp dynamical transition and lead, respectively, to a constant or an ever-increasing phase lag between the dimer orientation and the local nematic director.