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arXiv · 2112.14222

Antiferroelectric Smectic Ordering as a Prelude to the Ferroelectric Nematic:Introducing the Smectic $Z_A$ Phase

Xi Chen·Vikina Martinez·Eva Korblova·Guillaume Freychet·Mikhail Zhernenkov·Matthew A. Glaser·Cheng Wang·Chenhui Zhu·Leo Radzihovsky·Joseph E. Maclennan·David M. Walba·Noel A. Clark
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Abstract

We have structurally characterized the liquid crystal phase that appears as an intermediate state when a dielectric nematic, having polar disorder of its molecular dipoles, transitions to the almost perfectly polar-ordered ferroelectric nematic. This intermediate phase, which fills a 100-year-old void in the taxonomy of smectics and which we term the "smectic $Z_A$", is antiferroelectric, with the nematic director and polarization oriented parallel to smectic layer planes, and the polarization alternating in sign from layer to layer. The period of this polarization wave ($\sim$180 A) is mesoscopic, corresponding to $\sim$40 molecules side-by-side, indicating that this lamellar structure is collectively stabilized. A Landau free energy, originally formulated to model incommensurate antiferroelectricity in crystals, describes the key features of the nematic-Sm$Z_A$-ferroelectric nematic phase sequence.

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Xi Chen, Vikina Martinez, Eva Korblova, Guillaume Freychet, Mikhail Zhernenkov, Matthew A. Glaser, Cheng Wang, Chenhui Zhu, Leo Radzihovsky, Joseph E. Maclennan, David M. Walba, Noel A. Clark. 2021-12-28. Antiferroelectric Smectic Ordering as a Prelude to the Ferroelectric Nematic:Introducing the Smectic $Z_A$ Phase. https://doi.org/10.1073/pnas.2217150120

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