Abstract
Topological defects resulting from boundary constraints in confined liquid crystals have attracted extensive research interest. In this paper, we use numerical simulation to study the phase transition dynamics in the context of stochastic resonance in a bistable liquid crystal device containing defects. This device is made of nematic liquid crystals confined in a shallow square well and is described by the planar Lebwohl-Lasher model. The stochastic phase transition processes of the system in the presence of a weak oscillating potential is simulated using an overdamped Langevin dynamics. Our simulation results reveal that, depending on system size, the phase transition may follow two distinct pathways: In small systems the preexisting defect structures at the corners hold until the last stage and there is no newly formed defect point in the bulk during the phase transition and in large systems new defect points appear spontaneously in the bulk and eventually merge with the preexisting defects at the corners. For both transition pathways stochastic resonance can be observed, but the corresponding phase transition dynamics show a dramatic difference in their responses to the boundary anchoring strength. In small systems we observe a sticky-boundary effect for a certain range of anchoring strength in which the phase transition gets stuck and stochastic resonance becomes deactivated. Our work demonstrates the dynamical interplay among defects, noises, and boundary conditions in confined liquid crystals.
2 More- Received 31 May 2018
DOI:https://doi.org/10.1103/PhysRevE.98.032706
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