Kibble-Zurek mechanism in colloidal monolayers
Kibble-Zurek mechanism in colloidal monolayers
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DOI：
10.1073/pnas.1500763112
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发表时间：
2015-06-02
影响因子：
11.1
通讯作者：
Keim, Peter
中科院分区：
文献类型：
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作者：
Deutschlaender, Sven;Dillmann, Patrick;Keim, Peter
Kibble-Zurek机制描述了当系统通过二阶相变驱动时，拓扑缺陷结构的演化，如畴壁、弦和单极子。该模型在非常不同的尺度上使用，比如早期宇宙中的希格斯场，或者凝聚态系统中的量子流体。如果分离的区域由于有限的信号速度而太远而不能通信(例如，关于它们的方向或相位)，则在冷却期间自然会出现缺陷结构。这种因果关系的缺乏导致了具有不同(简并的)局部破缺对称性的分离的域。在这张图中，我们研究了凝聚态类物质中的非平衡动力学，这是一种2D胶体粒子系综。在平衡状态下，它遵循具有连续(类二阶)相变的所谓Kosterlitz-Thouless-Halperin-Nelson-Young(KTHNY)熔化情景。该整体暴露在一套有限的冷却速度下，覆盖了大约三个数量级。在这一过程中，我们通过视频显微镜对缺陷和磁畴结构进行了定量分析，并确定了相应长度尺度的比例作为冷却速度的函数。我们确实观察到了Kibble-Zurek机制对KTHNY普适性类所预测的标度。
The Kibble-Zurek mechanism describes the evolution of topological defect structures like domain walls, strings, and monopoles when a system is driven through a second-order phase transition. The model is used on very different scales like the Higgs field in the early universe or quantum fluids in condensed matter systems. A defect structure naturally arises during cooling if separated regions are too far apart to communicate (e.g., about their orientation or phase) due to finite signal velocity. This lack of causality results in separated domains with different (degenerated) locally broken symmetry. Within this picture, we investigate the non-equilibrium dynamics in a condensed matter analog, a 2D ensemble of colloidal particles. In equilibrium, it obeys the so-called Kosterlitz-Thouless- Halperin-Nelson-Young (KTHNY) melting scenario with continuous (second order-like) phase transitions. The ensemble is exposed to a set of finite cooling rates covering roughly three orders of magnitude. Along this process, we analyze the defect and domain structure quantitatively via video microscopy and determine the scaling of the corresponding length scales as a function of the cooling rate. We indeed observe the scaling predicted by the Kibble-Zurek mechanism for the KTHNY universality class.