Creation and topological charge switching of defect loops on a long fibre in the nematic liquid crystal

Abstract

We demonstrate new type of topological defects on a homeotropic fibre aligned perpendicular to the nematic director in a planar nematic cell. Contrary to expectations we can create defect loops which are encircling the fibre along its short axis and are strongly tilted with respect to the fibre. Such loops are always accompanied by two topological solitons, which emanate from the loop and propagate to the left and right hand side of the fibre. Unlike previously reported closed loops of either positive and negative charge, encircling the fibre parallel to the nematic director, these loops can carry either positive or negative charge, or can be charge neutral and very stable. We show how to switch the charge of individual loops from positive to neutral and negative charge by adding unit monopoles of appropriate topological charge. We demonstrate new type of interaction of dipolar colloids with these new topological entities on a fibre.

Electric field-induced crossover from 3D to 2D topological defects in a nematic liquid crystal: experimental verification

“…We also include modelling results that utilize our experimental conditions. Experimentally, there are several techniques to create defects at a surface and their associated disclination lines 15,[18][19][20][21][22][23][24] , as well as to manipulate these defect lines in 3D 15,[25][26][27][28][29][30][31][32][33][34][35] . Here we exploit techniques developed in our laboratory 15,35 , scribing two pairs of half-integer defect patterns (same-sign and opposite-sign) on a polymer-coated substrate, and impose uniform vertical (i.e., homeotropic) alignment of the director at the opposing substrate.…”