Ferroelectricity in a nematic liquid crystal under a direct current electric field.

We investigated the electrical properties of the liquid crystal compound 4-(4-nitrophenoxycarbonyl)phenyl 2,4-dimethoxybenzoate, known as RM734, exhibiting a ferroelectric nematic phase. The influence of alternating (AC) and direct (DC) current electric fields on the switching process of the polarization vector and dielectric constant of planarly aligned ferronematic and nematic phases were examined. The decrease of the real part of electric permittivity in the ferronematic phase and the creation of a ferroelectric order in the nematic phase under a DC field were demonstrated. The analysis of the results reveals the latching of the ferroelectric state. The applied DC field created a ferroelectric mode in the nematic phase. A new model of collective and molecular relaxations considering the domain structure of the ferronematic phase was proposed. The temperature and DC field dependence of dielectric properties was shown. Spontaneous polarization was measured using the field reversal technique. The spontaneous polarization value reaches the maximum at a fixed temperature.