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arXiv · 1910.03999

Ferroelectric-ferroelastic phase transition in a nematic liquid crystal

Nerea Sebastián·Luka Cmok·Richard J. Mandle·María Rosario de la Fuente·Irena Drevenšek Olenik·Martin Čopič·Alenka Mertelj
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Abstract

Ferroelectric ordering in liquids is a fundamental question of physics. Here, we show that ferroelectric ordering of the molecules causes formation of recently reported splay nematic liquid-crystalline phase. As shown by dielectric spectroscopy, the transition between the uniaxial and the splay nematic phase has the characteristics of a ferroelectric phase transition, which drives an orientational ferroelastic transition via flexoelectric coupling. The polarity of the splay phase was proven by second harmonic generation (SHG) imaging, which additionally allowed for determination of the splay modulation period to be of the order of 5 - 10 microns, also confirmed by polarized optical microscopy. The observations can be quantitatively described by a Landau-de Gennes type of macroscopic theory.

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Nerea Sebastián, Luka Cmok, Richard J. Mandle, María Rosario de la Fuente, Irena Drevenšek Olenik, Martin Čopič, Alenka Mertelj. 2019-10-09. Ferroelectric-ferroelastic phase transition in a nematic liquid crystal. https://doi.org/10.1103/physrevlett.124.037801

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