title: Stick-slip motion of surface point defects prompted by magnetically controlled colloidal-particle dynamics in nematic liquid crystals.
abstract: We explore the dynamics of topological point defects on surfaces of magnetically responsive colloidal microspheres in a uniformly aligned nematic liquid crystal host. We show that pinning of the liquid crystal director to a particle surface with random nanostructured morphology results in unexpected translational dynamics of both particles and topological point defects on their surfaces when subjected to rotating magnetic fields. We characterize and quantify the "stick-slip" motion of defects as a function of field rotation rates as well as temperature, demonstrating the roles played by the competition of elastic forces, surface anchoring, and magnetic torques on the sphere as well as random-surface-mediated pinning of the easy axis of the nematic director on colloidal microspheres. We analyze our findings through their comparison to similar dynamic processes in other branches of science.
authors.affiliation: Department of Physics, University of Colorado at Boulder, Boulder, Colorado 80309, USA.
authors.forename: Michael C M
authors.initials: MC
authors.lastname: Varney
authors.affiliation: Department of Physics, University of Colorado at Boulder, Boulder, Colorado 80309, USA.|Materials Science and Engineering Program, University of Colorado at Boulder, Boulder, Colorado 80309, USA.
authors.forename: Qiaoxuan
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Department of Physics, University of Colorado at Boulder, Boulder, Colorado 80309, USA.|Materials Science and Engineering Program, University of Colorado at Boulder, Boulder, Colorado 80309, USA.|Department of Electrical, Computer, and Energy Engineering and Soft Materials Research Center, University of Colorado at Boulder, Boulder, Colorado 80309, USA.|Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado at Boulder, Boulder, Colorado 80309, USA.
authors.forename: Ivan I
authors.initials: II
authors.lastname: Smalyukh