Active crystals on a sphere
Abstract
Two-dimensional crystals on curved manifolds exhibit nontrivial defect structures. Here, we consider "active crystals" on a sphere, which are composed of self-propelled colloidal particles. Our work is based on a new phase-field-crystal-type model that involves a density and a polarization field on the sphere. Depending on the strength of the self-propulsion, three different types of crystals are found: a static crystal, a self-spinning "vortex-vortex" crystal containing two vortical poles of the local velocity, and a self-translating "source-sink" crystal with a source pole where crystallization occurs and a sink pole where the active crystal melts. These different crystalline states as well as their defects are studied theoretically here and can in principle be confirmed in experiments.
Cite
@article{arxiv.1802.04913,
title = {Active crystals on a sphere},
author = {Simon Praetorius and Axel Voigt and Raphael Wittkowski and Hartmut Löwen},
journal= {arXiv preprint arXiv:1802.04913},
year = {2018}
}
Comments
11 pages, 12 figures