Active materials, composed of internally driven particles, have properties that are qualitatively distinct from matter at thermal equilibrium. However, the most spectacular departures from equilibrium phase behavior are thought to be confined to systems with polar or nematic asymmetry. In this Letter, we show that such departures are also displayed by more symmetric phases such as hexatics if, in addition, the constituent particles have chiral asymmetry. We show that chiral active hexatics whose rotation rate does not depend on density have giant number fluctuations. If the rotation rate depends on density, the giant number fluctuations are suppressed due to a novel orientation-density sound mode with a linear dispersion which propagates even in the overdamped limit. However, we demonstrate that beyond a finite but large length scale, a chirality and activity-induced relevant nonlinearity invalidates the predictions of the linear theory and destroys the hexatic order. In addition, we show that activity modifies the interactions between defects in the active chiral hexatic phase, making them nonmutual. Finally, to demonstrate the generality of a chiral active hexatic phase we show that it results from the melting of chiral active crystals in finite systems.

中文翻译：

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手性活性六角形：巨数涨落，波动和破坏序

由内部驱动的颗粒组成的活性材料，其性质与热平衡时的物质有质的区别。但是，人们认为平衡相行为的最明显偏离仅限于极性或向列不对称的系统。在这封信中，我们表明，如果组成粒子具有手性不对称性，那么这种偏离也可以通过更对称的相（例如六氟）来显示。我们表明，其旋转速度不依赖于密度的手性活性六官能团具有巨大的数量波动。如果旋转速度取决于密度，则由于具有线性色散的新型定向密度声模，即使在超阻尼极限下也能传播，因此可以抑制巨数波动。但是，我们证明了，除了有限但很大的长度范围外，手性和活动性引起的相关非线性使线性理论的预测无效并破坏了六次序。此外，我们表明，活性会改变活性手性六价相中缺陷之间的相互作用，使它们互不相干。最后，为了证明手性活性己酸相的一般性，我们证明了它是由于手性活性晶体在有限系统中的熔化而产生的。