Colloids in Cholesterics: Size-Dependent Defects and Non-Stokesian Microrheology
arXiv:1101.1487 · doi:10.1103/PhysRevLett.105.178302
Abstract
We simulate a colloidal particle (radius R) in a cholesteric liquid crystal (pitch p) with tangential order parameter alignment at the particle surface. The local defect structure evolves from a dipolar pair of surface defects (boojums) at small R/p to a pair of twisted disclination lines wrapping around the particle at larger values. On dragging the colloid with small velocity v through the medium along the cholesteric helix axis (an active microrheology measurement), we find a hydrodynamic drag force that scales linearly with v but superlinearly with R-in striking violation of Stokes' law, as generally used to interpret such measurements.
4 pages, 4 figures
References in corpus (3)
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