Spontaneous symmetry breaking in polar fluids

• Published in: Nature communications Vol. 15; no. 1; pp. 5845 - 9
• Main Authors: Gibb, Calum J., Hobbs, Jordan, Nikolova, Diana I., Raistrick, Thomas, Berrow, Stuart R., Mertelj, Alenka, Osterman, Natan, Sebastián, Nerea, Gleeson, Helen F., Mandle, Richard. J.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 11.07.2024; Nature Publishing Group; Nature Portfolio
• Subjects: 639/638/298/919; 639/766/94; Ambient temperature; Antiferroelectricity; Binary mixtures; Broken symmetry; Crystals; Ferroelectric materials; Humanities and Social Sciences; Iron constituents; Lamellar structure; Light reflection; Liquid crystals; Melting point; Melting points; Molecular structure; multidisciplinary; Phases; Room temperature; Science; Science (multidisciplinary); Spin structure; Symmetry
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-50230-2

Spontaneous symmetry breaking and emergent polar order are each of fundamental importance to a range of scientific disciplines, as well as generating rich phase behaviour in liquid crystals (LCs). Here, we show the union of these phenomena to lead to two previously undiscovered polar liquid states of matter. Both phases have a lamellar structure with an inherent polar ordering of their constituent molecules. The first of these phases is characterised by polar order and a local tilted structure; the tilt direction processes about a helix orthogonal to the layer normal, the period of which is such that we observe selective reflection of light. The second new phase type is anti-ferroelectric, with the constituent molecules aligning orthogonally to the layer normal. This has led us to term the phases the Sm C P H and SmA AF phases, respectively. Further to this, we obtain room temperature ferroelectric nematic (N F ) and Sm C P H phases via binary mixture formulation of the novel materials described here with a standard N F compound (DIO), with the resultant materials having melting points (and/or glass transitions) which are significantly below ambient temperature. The new soft matter phase types discovered herein can be considered as electrical analogues of topological structures of magnetic spins in hard matter. Spontaneous symmetry breaking and emergent polar order are key to liquid crystal phase behaviour. This study reveals two new polar liquid states with lamellar structures, providing novel insights into electrical analogues of magnetic spin structures.