Altering the Position of Topological Defects in Nematic Shells

Topological defects (TDs) in liquid crystals may have their locations experimentally altered by locally distorting the liquid crystalline (LC) order, e.g., by the melting induced by optical tweezers. In this research, we investigated the nematic ordering profiles and accompanying topological defect configurations in thin nematic liquid crystalline shells that are subject to externally forced local LC order distortions. We show that inside curved LC films these manipulations are greatly influenced by local Gaussian curvature if it displays strong spatial variability. We use a mesoscopic model in which the curvature of the surface and the nematic order parameter tensor serve to explain the shell geometry and LC orientational order. We demonstrate that TDs are rather tightly "glued" to a local Gaussian curvature on increasing the prolateness of shells. Keywords: Topological defects; Liquid crystals; Distortions; Gaussian curvature; Prolate shells