Spontaneous polar and chiral symmetry breaking in ordered fluids -- heliconical ferroelectric nematic phases

Abstract: It is known that the chiral interaction described by Dzyaloshinskii-Moriya (DMI) term lead to the plethora of topological structures of magnetic spins, such as helical or skyrmion phases. Here we present the that analogues electrical DMI can lead to similar structural complexity of electric dipoles in soft matter. We report on a new polar liquid phase in which achiral molecules spontaneously form a heliconical structure. The helical pitch is comparable to the wavelength of visible light and unwinds critically at the transition to a uniformly polar, ferroelectric nematic phase. Although this new liquid crystalline phase resembles the twist-bend nematic phase, the mechanism of its formation is different and is attributed to electrical interactions that cause non-collinear arrangement of electric dipoles, similarly as observed for spins in magnetic systems.