Temperature- and electric-field-induced inverse Freedericksz transition in a nematogen with weak surface anchoring

Abstract

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.