The odd free surface flows of a colloidal chiral fluid
The odd free surface flows of a colloidal chiral fluid
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DOI：
10.1038/s41567-019-0603-8
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发表时间：
2019-11-01
期刊：
影响因子：
19.6
通讯作者：
Irvine, William T. M.
中科院分区：
文献类型：
--
作者：
Soni, Vishal;Bililign, Ephraim S.;Irvine, William T. M.
在简单的流体中，如水，在宇称和时间反转对称性下的不变性决定了组成原子的旋转是由流动决定的，粘性应力抑制了运动。通过旋转原子构件来激活流体的旋转自由度打破了这些限制，因此一直是经典流体和量子流体的基本理论兴趣的主题。然而，创造一种分离手性流体动力学现象的模型液体在实验上仍然难以捉摸。在这里，我们报道了一种由数百万个旋转的胶体磁铁组成的内聚二维手性液体的创建，并研究了它的流动。我们发现，耗散粘性“边缘泵浦”是手征流体动力学的关键和一般机制，它驱动单向表面波和不稳定性，这在常规流体中是没有的。手性表面动力学的光谱测量表明存在霍尔粘度，这是手性流体的一种实验难以捉摸的特性。精确的测量和与理论的比较表明，与最小手征流体动力学模型具有很好的一致性，为手征流体动力学的实验探索铺平了道路。
In simple fluids, such as water, invariance under parity and time-reversal symmetry imposes that the rotation of constituent 'atoms' is determined by the flow and that viscous stresses damp motion. Activation of the rotational degrees of freedom of a fluid by spinning its atomic building blocks breaks these constraints and has thus been the subject of fundamental theoretical interest across classical and quantum fluids. However, the creation of a model liquid that isolates chiral hydrodynamic phenomena has remained experimentally elusive. Here, we report the creation of a cohesive two-dimensional chiral liquid consisting of millions of spinning colloidal magnets and study its flows. We find that dissipative viscous 'edge-pumping' is a key and general mechanism of chiral hydrodynamics, driving unidirectional surface waves and instabilities, with no counterpart in conventional fluids. Spectral measurements of the chiral surface dynamics suggest the presence of Hall viscosity, an experimentally elusive property of chiral fluids. Precise measurements and comparison with theory demonstrate excellent agreement with a minimal chiral hydrodynamic model, paving the way for the exploration of chiral hydrodynamics in experiment.