Ferroelectric and hyper dielectric modes in ferronematic liquid crystals

Abstract

Binary mixtures of the ferronematic liquid crystal DIO with the recently reported non-ferroelectric liquid crystalline material WJ-16 exhibiting colossal permittivity (CP) ≈ 5000 and superparaelectricity were studied by polarizing optical microscopy (POM), electrical switching, and dielectric spectroscopy. Three mixtures with different WJ-16 concentrations ranging from 10, 25 to 50% (w/w) in DIO as the host were prepared. Our original expectation was the observation of new nematic compositions with both ferroelectric nematic (N_F) and the non-ferroelectric CP phases. We found that the non-ferroelectric phase in mixtures exhibits a CP mode, originally observed in pure WJ-16. Dielectric spectroscopy of mixtures shows two distinct relaxation processes: the typical paraelectric response and the CP mode. This CP mode in the mixtures is not superparaelectric, and here it is defined as a hyper-dielectric mode. This is the first direct demonstration of the mixtures having both ferroelectric and hyper-dielectric phases in liquid crystalline materials.