Electro-optic demonstration of ferroelectricity in the thermotropic nematic liquid crystal DIO*

The Boulder group recently showed that the liquid crystal RM734 possesses a ferroelectric nematic (N_F) phase [1]. In the search for additional ferroelectric nematic liquid crystals, we studied the liquid crystal DIO, which was previously reported to be ferroelectric-like [2]. In an antiparallel-rubbed liquid crystal cell, polarized light microscopy of DIO in the polar phase reveals two twisted states of the director and polarization field that have opposite handedness. These chiral states can be converted from one to the other with an applied electric field. This phenomenology is similar to that observed in RM734 in the same type of cell. The ferroelectric polarization of DIO obtained by analyzing the switching current generated during reversal of an in-plane field was found to be similar in magnitude to that of RM734. These observations confirm that the previously reported polar phase is indeed ferroelectric, as tentatively suggested by Kikuchi et al. [2].
[1] X. Chen et al. PNAS 2020
[2] H.Nishikawa et al. AdvMat 2017
Correspondence Author: joseph.maclennan@colorado.edu