Ferromagnetic nanoparticle-mediated manipulation of nematic liquid crystal properties: Threshold voltage reduction and alignment enhancement

Present investigation covers the dielectric and electro-optical study of nematic liquid crystal (NLC) 1823 A dispersed with the ferromagnetic nanoparticles (FNPs) Fe3O4. Three concentrations of nanoparticles (NPs) in the NLC matrix namely 0.1 wt/wt%, 0.3 wt/wt%, and 0.5 wt/wt% are prepared and perceptible changes in the various properties are compared with the pure NLC. Variation of dielectric permittivity (εꓕ) with the variation of frequency and variation of temperature is studied. Dielectric permittivity (εꓕ) is just found to be decreased as we increased the concentration of NPs, which shows that the applied electric field is less impactful on the prepared composites. It is also found that the dielectric permittivity (εꓕ) is increased with the increase of temperature. Birefringence is found to be decreased with the increase in the concentration of the NPs which showed that the orientational order of NLC 1823 A is got to be disturbed due to the presence of the NPs. It is also shown that as the temperature is increased, birefringence is found to get decreased due to its approach toward isotropic phase. Threshold voltage is found to be decreased by 56.25% for the 0.3 wt/wt% and by 25% for 0.1 wt/wt% composite which are pretty good result in context of achieving the low power optical switching devices. The results achieved are tried to be explained on account of the interaction between NLC and NPs.