The recently discovered ferroelectric nematic (NF) 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 NF 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 NF 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

Fluid superscreening and polarization following in confined ferroelectric nematics / Caimi, F.; Nava, G.; Fuschetto, S.; Lucchetti, L.; Paiè, P.; Osellame, R.; Chen, X.; Clark, N. A.; Glaser, M. A.; Bellini, T.. - In: NATURE PHYSICS. - ISSN 1745-2481. - (2023).

Fluid superscreening and polarization following in confined ferroelectric nematics

G. Nava;L. Lucchetti;
2023-01-01

Abstract

The recently discovered ferroelectric nematic (NF) 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 NF 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 NF 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
2023
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11566/326477
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