Revealing the polar nature of a ferroelectric nematic by means of circular alignment

The recent discovery of spontaneously polar nematic liquid crystals—so-called ferroelectric nematics—more than a century after the first discussions about their possible existence—has attracted large interest, both from fundamental scientific and applicational points of view. However, the experimental demonstration of such a phase has, so-far, been non-trivial. Here I present a direct method for the experimental verification of a ferroelectric nematic liquid crystal phase. The method utilizes a single sample cell where the two substrates are linearly and circularly rubbed, respectively, and the ferroelectric nematic phase (N(F)) is revealed by the orientation of the resulting disclination lines in the cell.