Colloidal Templating at a Cholesteric-Oil Interface: Assembly Guided by an Array of Disclination Lines

We simulate colloids (radius R similar to 1 mu m) trapped at the interface between a cholesteric liquid crystal and an immiscible oil at which the helical order (pitch p) in the bulk conflicts with the orientation induced at the interface, stabilizing an ordered array of disclinations. For a weak anchoring strength W of the director field at the colloidal surface, this creates a template, favoring particle positions either on top of or midway between defect lines, depending on alpha = R/p. For small alpha, optical microscopy experiments confirm this picture, but for larger alpha no templating is seen. This may stem from the emergence at moderate W of a rugged energy landscape associated with defect reconnections.