Structure and dynamics of kinked line-slip defects in confined colloidal crystals

Line-slip defects are found in crystals confined to the surface of a finite sized cylinder. These defects are identified by a line of particle pairs, each of which has one fewer contact than in bulk. They are known to appear in ground state of a cylindrical crystal when the cylinder cannot accommodate a perfect crystal. We study the structure and dynamics of these defects using an experimental system where submicron-sized colloidal spheres self-assemble into hexagonal lattices on a silica fiber with a diameter of a few micrometers. We find that most line-slip defects have kinks in them. A kink can be recognized from a discontinuity in the line-slip structure. The simplest kink in a line slip has four fewer bonds compared to a straight line-slip without any kink. We observe that the number of kinks in a line-slip defect does not change significantly over long time, but instead shows small fluctuations. We show that the average kink density is related to the average roughness of a 2D crystal grain. We find that by tuning the strength of interaction, we can tune the size of the crystal and the total length of the line-slip defects, allowing us to control the number of kinks in a line-slip defect and hence its shape.