As a result of non-equilibrium forces, purely repulsive self-propelled particles undergo macro-phase separation between a dense and a dilute phase. We present a thorough study of the ordering kinetics of such Motility-Induced Phase Separation (MIPS) in Active Brownian Particles in two-dimensions, and we show that it is generically accompanied by micro-phase separation. The growth of the dense phase follows a law akin to the one of liquid-gas phase separation. However, it is made of a mosaic of hexatic micro-domains whose size does not coarsen indefinitely, leaving behind a network of extended topological defects from which microscopic dilute bubbles arise. The characteristic length of these finite-size structures increases with activity, independently of the choice of initial conditions.

中文翻译：

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二维活动布朗粒子系统中微观和宏观动力诱导的相分离

由于不平衡力的作用，纯排斥的自推进颗粒在致密相和稀相之间经历了宏观相分离。我们目前对二维的活性布朗粒子中这种由运动引起的相分离（MIPS）的有序动力学进行了深入研究，并且我们发现它通常伴随着微相分离。致密相的生长遵循类似于液相分离法的定律。但是，它是由六边形微区的马赛克制成的，其尺寸不会无限扩大，留下了扩展的拓扑缺陷网络，从中会产生微观的稀疏气泡。这些有限尺寸结构的特征长度随活动而增加，与初始条件的选择无关。