Fluid superscreening and polarization following in confined ferroelectric nematics

The recently discovered ferroelectric nematic (N-F) liquid-crystal phase exhibits a spontaneous polarization field that is both orientationally fluid like a liquid crystal and large in magnitude like a solid ferroelectric. This combination imparts this phase with a unique electrostatic phenomenology and response to applied fields. Here we probe this phase by applying a small electric field to ferroelectric nematics confined in microchannels that connect electrodes through straight and curved paths and find that the N-F phase smoothly orders with its polarization following the channels despite their winding paths. This implies a corresponding behaviour of the electric field. On inversion of the electric field, the polar order undergoes a multistage switching process dominated by electrostatic interactions. We also find multistage polarization switching dynamics in the numerical simulations of a quasi-two-dimensional continuum model of channel-confined N-F liquid crystals, enabling the exploration of their internal structural and electrical self-organization. This indicates that polarization alignment and electric-field guiding are direct consequences of fluid superscreening-the prompt elimination of electric-field components normal to the channel walls by polarization reorientation. This response mimics the behaviour expected for ultrahigh-permittivity dielectrics, but with patterns of charge accumulation and local ordering unique to fluid ferroelectrics.The ferroelectric uniaxial nematic liquid-crystal phase features a freely reorientable polarization field. When confined in microchannels and subjected to electric fields, this polarization is now found to align with the channels due to a superscreening effect.