Kinetics of Directrons in Liquid Crystals with Horizontal Fringe Electric Fields

Three-dimensional director bullets, or directrons, emerging in liquid crystals under electric fields, are fascinating entities within the realm of out-of-equilibrium nematics, attracting significant attention due to their distinctive behaviors. Understanding the generation dynamics and propagation mechanism of directrons is of fundamental importance for both physical research and potential practical applications. While the behaviors of directrons can be manipulated through the modulation of applied electric fields, the impact of fringe electric fields on their dynamics remains unexplored. Herein, we apply a combination of experimental observation, computational simulations, and theoretical analysis to examine the kinetics of directrons in asymmetrically patterned electrode domains, where the fringe electric fields are enhanced. These asymmetric-electrode-induced directrons (AEIDs), subjected to a nonzero horizontal alternating electric field, exhibit a lower threshold of electric fields, higher peak densities and larger deflection angles compared to their counterparts from symmetrically patterned electrodes. This facilitation originates from boundary-induced director distortions, in combination with the additional torque from the horizontal electric field component. Moreover, by changing the geometrical configuration of the asymmetric electrodes, we find that these AEIDs tend to form a distinct collective motion pattern. We attribute these phenomena to the director distortion, arising due to the influence of the fringe electric fields. These findings open avenues for actively tailoring soliton dynamics in liquid crystals, offering design strategies for tunable microscale transport and information encoding systems.