Weak thermal transport in a highly polar ferroelectric nematic phase: potential material for quantum electronics

A new LC phase, viz, ferroelectric nematic ( NF) phase, has recently been realized experimentally in the RM734 material, following the theoretical prediction in 1910 by Peter Debye and Max Born. Due to the breaking of inversion symmetry, the NF phase of RM734 exhibits polarization in the order of μC cm −2, almost 1000 times greater than that of normal SmC*-phase-based ferroelectric liquid crystals, representing a potentially significant discovery from both basic and technological perspectives. The polarized optical micrograph of the RM734 material in the NF phase reflects a chevron-modulated ferroelectric nematic state, where elastic anisotropy and confinement led to the formation of periodic chevron defects. The electro-optical study revealed that the response times of the RM734 material in the NF and nematic phases have been found to be ≈ 0.5 ms and 100 μs, respectively. The thermal parameters, including thermal diffusivity, thermal effusivity, and thermal conductivity, have been ascertained utilizing the photopyroelectric technique. The measured values of thermal diffusivity, thermal effusivity, and thermal conductivity at 160 ∘C are αm = (2.28±0.54)×10−8 m 2 s −1, em = 632 ± 70 Ws 1/2m −2K −1, and κm = 0.095 ± 0.022 Wm −1K −1, indicating relatively low values, rendering a weak thermal transport in the nematic phase. Moreover, in the NF phase, these thermal parameters are diminished by 10%–30%, resulting in significantly low thermal conductivity in the NF phase. The NF material demonstrated a significant potential as a futuristic material for quantum electronics due to its high polarization and low thermal conductivity.