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Dr. Jun-ichi Fukuda: Skyrmions and exotic defect structures in a confined chiral liquid crystal

Date: 22. 3. 2011
Source: Physics lectures
v sredo, 23. 3. 2011, ob 15:15 v Kuščerjevem seminarju (4/414) na FMF, Jadranska 19, Ljubljana

Dr. Jun-ichi Fukuda,
National Institute of Advanced Industrial Science and Technology, Japan,
Fakulteta za Matematiko in Fiziko, Univerza v Ljubljani  

We investigate numerically the structures of a chiral liquid crystal confined in a thin parallel cell whose surfaces impose homeotropic or fixed planar anchoring. We are interested in the cases in which cholesteric blue phases are stable in the bulk, and discuss how the structures of blue phases are changed in the presence of confining surfaces. We find various exotic defect structures completely different from those of bulk cholesteric blue phases. In the case of homeotropic surface anchoring, depending on the cell thicknesses and temperatures, we observe, for example, a parallel array of disclination lines forming double helices, and a hexagonal array of point-like excitations referred to as Skyrmions [1]. When the surfaces adopt fixed planar anchoring and the cell thickness is incommensurate with the intrinsic cholesteric pitch, the frustration due to the incommensurability is relaxed to form a regular array of ring defects.

[1] J. Fukuda and S. Zumer, Nature Communications, March 22, 2011 (DOI: 10.1038/ncomms1250)