There are many examples of interacting particles that have both repulsive and attractive interaction terms. Assemblies of such particles can form clumps, gel type states, labyrinths and other patterns, while two-dimensional systems with purely repulsive interactions typically form hexagonal crystals. Here we examine the two-dimensional pattern formation of colloids with competing interactions in the presence of a quasi-one dimensional periodic substrate. For soft matter systems, such substrates can be created by various optical means. We show that the substrate can induce various patterns including commensurate bubble phases as well as modulated stripes aligned with the substrate. Beyond colloids, these results should also be general to other systems that can be modeled as particles with competing interactions moving over a surface with a quasi-one dimensional periodic substrate or modulation.

Date Published: 16 September 2014
PDF: 10 pages
Proc. SPIE 9164, Optical Trapping and Optical Micromanipulation XI, 916420 (16 September 2014); doi: 10.1117/12.2063487

Published in SPIE Proceedings Vol. 9164:
Optical Trapping and Optical Micromanipulation XI
Kishan Dholakia; Gabriel C. Spalding, Editor(s)