Spontaneous mirror symmetry breaking by formation of chiral structures from achiral building blocks and emergent polar order are phenomena rarely observed in fluids. Separately, they have both been found in certain nematic liquid crystalline phases; however, they have never been observed simultaneously. Here, we report a heliconical arrangement of achiral molecules in the ferroelectric nematic phase. The phase is thus spontaneously both polar and chiral. Notably, the pitch of the heliconical structure is comparable to the wavelength of visible light, giving selective reflection controllable by temperature or application of a weak electric field. Despite bearing resemblance to the heliconical twist-bend nematic phase, this chiral ferroelectric nematic phase arises from electrical interactions that induce a noncollinear orientation of electric dipoles.

中文翻译：

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极性流体螺旋铁电向列相中自发手性对称性破缺


由非手性构件形成手性结构而自发打破镜像对称性以及出现的极序是在流体中很少观察到的现象。另外，它们都被发现存在于某些向列液晶相中。然而，它们从未被同时观察到。在这里，我们报告了铁电向列相中非手性分子的螺旋排列。因此，该相自发地具有极性和手性。值得注意的是，螺旋结构的节距与可见光的波长相当，从而可以通过温度或施加弱电场来控制选择性反射。尽管与螺旋扭转弯曲向列相相似，但这种手性铁电向列相是由电相互作用引起的，该相互作用引起电偶极子的非共线取向。