Rigid-Body Rotation of Cholesteric Droplets under a Heat Flux Parallel to Their Helical Structure

Abstract

Droplets of cholesteric liquid crystals coexisting with their isotropic phase are known to exhibit unidirectional steady change in their textures when subjected to a heat flux. Although the observation under a polarizing microscope is quite clear, it is still controversial whether the textural change is ascribed to rigid-body rotation of the droplet or pure director rotation. In this study, detecting the flow field, we confirmed the rigid-body rotation of the droplets even when the helical axis is parallel to the heat flux. Considering the ratio of the surface anchoring and the Frank elasticity and that of the elasticity and the Lehmann torque, we gave a reasonable explanation why the rigid-body rotation should be chosen.