Colloquium: Disclination loops, point defects, and all that in nematic liquid crystals

The homotopy theory of topological defects is a powerful tool for organizing and unifying many ideas across a broad range of physical systems. Recently, experimental progress was made in controlling and measuring colloidal inclusions in liquid crystalline phases. The topological structure of these systems is quite rich but, at the same time, subtle. Motivated by experiment and the power of topological reasoning, the classification of defects in uniaxial nematic liquid crystals was reviewed and expounded upon. Particular attention was paid to the ambiguities that arise in these systems, which have no counterpart in the much-storied XY model or the Heisenberg ferromagnet. Disciplines Physical Sciences and Mathematics | Physics Comments Alexander, G. P., Chen, B. G., Matsumoto, E. A., & Kamien, R. D. (2012). Colloquium: Disclination loops, point defects, and all that in nematic liquid crystals. Reviews of Modern Physics, 84(2), 497-514. doi: 10.1103/ RevModPhys.84.497 © 2012 American Physical Society This journal article is available at ScholarlyCommons: http://repository.upenn.edu/physics_papers/250 Colloquium: Disclination loops, point defects, and all that in nematic liquid crystals