DIELECTRIC AND ELECTRO-OPTICAL EFFECTS IN NEMATIC LIQUID CRYSTALS

Abstract

The present work studied the physical properties of a nematic LC material compound RT11165. The recently discovered ferroelectric nematic phase that carries a non-zero dipole moment exhibits in this material. Experimentally we used the Fréedericksz transition method in the nematic phase by measuring the light intensity through a planar nematic layer as a function of the amplitude and frequency of an applied voltage. The threshold voltage shows dependence on the frequency. In addition, the dielectric anisotropy and the splay elastic constant K11 are measured. The dielectric anisotropy indicates critical behavior at high frequencies relatively low as cooling toward the NF phase, while at low frequencies, it shows strong positive dielectric permittivity. Also, the dielectric spectroscopy shows two molecular relaxation modes detected at low frequency and temperature in the perpendicular component of the dielectric permittivity, and the strength of the relaxation frequency was found to be decreased. In contrast, it increases rapidly and smoothly in the parallel component.