Director Fields Around Spherical and Cylindrical Micro Particles in a Liquid Crystal Host

Abstract

Director fields around spherical and cylindrical micro particles embedded in a uniformly aligned nematic liquid crystal are investigated by means of fluorescence confocal polarizing microscopy. Both dipolar configurations (point-like defects) and quadrupolar configurations (ring-like defect lines) are observed for spherical particles. However, only defect lines appear in the vicinity of particles with cylindrical shape. In contrast to previous predictions for sphero-cylinders, the defect lines around the cylindrical particles studied here seem to be pinned at the cylinder edges. The experimental results are in good agreement with numerical simulations.

Keywords:

• liquid crystals
• micro particles
• suspensions
• topology

Acknowledgments

Financial support of this work by the European Science Foundation (EUROCORES, 05-SONS-FP-014) and the German Research Foundation (DFG, KI 411/14-1) is gratefully acknowledged.