We report electric field dependence of the anchoring transition in a mesogen on cooling in a cell with perfluoropolymer treated surfaces. Below a crossover voltage V(co) the transition is discontinuous between planar and homeotropic alignments, and as the temperature is lowered, the transition temperature decreases quadratically with the field. Above V(co) the transition is continuous between planar and tilted alignments, the transition temperature decreasing essentially linearly with the rms field. We develop a simple model to account for these results and argue that the higher field regime corresponds to a temperature driven inverse Freedericksz transition in which the director orientation starts tilting at the weakly anchored surfaces while the tilt angle remains zero at the midplane of the cell.
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Article Synopsis
- The study builds on Kumar et al.'s discovery of the inverse Fréedericksz transition, exploring the stability and configurations in a Fréedericksz cell under weak planar conditions.
- The simple one-constant Frank theory indicates that the equilibrium behavior can be modeled by a nonlinear pendulum equation, leading to multiple potential solutions due to symmetry.
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