title: Colloids in cholesterics: size-dependent defects and non-stokesian microrheology.
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.
authors.affiliation: SUPA, University of Edinburgh, United Kingdom.
authors.forename: J S
authors.initials: JS
authors.lastname: Lintuvuori
authors.forename: K
authors.initials: K
authors.lastname: Stratford
authors.forename: M E
authors.initials: ME
authors.lastname: Cates
authors.forename: D
authors.initials: D
authors.lastname: Marenduzzo