An escaped radial director profile in a nematic liquid crystal cell can be transformed into a pair of strength m = +1/2 surface defects (and their associated disclination lines) at a threshold electric field.

No abstract

A patterned surface defect of strength m = +1 and its associated disclination lines can decompose into a pair of surface defects and disclination lines of strength m = +1/2. Black bar represents 10 μm.

(a) 3D visualization of a SmA divot measured by optical profilometry. (b) Polarized optical microscopy image showing the OS pattern between crossed polarizers, overlaid by the parameters used in our model. (c) Side view sketch showing the different parameters in our model.

A wedge cell made of homeotropically treated glass plates is filled with a chirally doped nematic liquid crystal. When a sufficiently large magnetic field is applied in the cell plane, a bend-like distortion occurs above a Fréedericksz threshold field Hth. Hth is reduced from the achiral case because of a field-induced bend distortion that facilitates a chiral twist distortion. Measurements of Hth vs sample thickness are reported and compared favorably with a theoretical model presented herein. A further theoretical comparison is made between Hth and the electric-field-induced transition in a geometry, exhibiting a 2π azimuthal degeneracy. The results may have technological implications in, for example, in-plane switching devices.