Spheres, doughnuts, pretzels and frustrated nematic order
By: Alberto Fernandez de las Nieves
From: Georgia Tech
At: Instituto de Investigação Interdisciplinar, Anfiteatro
[2012-06-06]
Ordered materials on curved spaces often have topological defects in their ground states. The north and south poles of the Earth’s globe and the pentamers of the soccer ball provide familiar realizations of this fact. When the order is nematic and the space is a spherical shell, a variety of defect structures is observed; these all comply with the topological constraints imposed by the spherical geometry. Our experimental results and elastic energy calculations suggest that it is the shell thickness inhomogeneity what controls the defect location in this case. For topologies different from the spherical, the defect structures are expected to be different than those observed in spheres. Motivated by this, we have generated and stabilized non-zero genus droplets and have recently began to look at the ordering when a nematic liquid crystal lives inside these non-spherical spaces.