Order Reconstruction in a Nanoconfined Nematic Liquid Crystal between Two Coaxial Cylinders

The dynamics of a disclination loop (s = ±1/2) in nematic liquid crystals constrained between two coaxial cylinders were investigated based on two-dimensional Landau–de Gennes tensorial formalism by using a finite-difference iterative method. The effect of thickness (d = R(2) − R(1), where R(1) and R(2) represent the internal and external radii of the cylindrical cavity, respectively) on the director distribution of the defect was simulated using different R(1) values. The results show that the order reconstruction occurs at a critical value of d(c), which decreases with increasing inner ratio R(1). The loop also shrinks, and the defect center deviates from the middle of the system, which is a non-planar structure. The deviation decreases with decreasing d or increasing R(1), implying that the system tends to be a planar cell. Two models were then established to analyze the combined effect of non-planar geometry and electric field. The common action of these parameters facilitates order reconstruction, whereas their opposite action complicates the process.