History-Dependent Patterns in Randomly Perturbed Nematic Liquid Crystals
Figure 1
(a) In weak surface interaction limit an impurity does not essentially disturb LC environment. (b) Schematic presentation of topological defect dipole. The dipole is enforced by a spherical particle enforcing homeotropic anchoring at the LC-particle interface. Consequently, from LC perspective the particle carries topological charge and can be viewed as a virtual topological defect. Due to the conservation of the total topological charge, an antidefect appears in the vicinity. The defect and antidefect attract each other but cannot mutually annihilate due to the virtual character of the defect. Note that the particle in absence of LC does not enforce any local orientational preference. However, topologically enforced formation of anti-defect necessarily breaks the initial isotropic symmetry.
