# Motility-Induced Microphase and Macrophase Separation in a Two-Dimensional Active Brownian Particle System

Source: [Motility-Induced Microphase and Macrophase Separation in a Two-Dimensional Active Brownian Particle System](<https://www.sota2.com/research/paper/68fa40001e209131ce8eff75>)

Collection index: [llms.txt](<https://www.sota2.com/research/llms.txt>)

Data updated: 2025-10-25T02:33:29.490Z

Authors: Claudio B. Caporusso, Pasquale Digregorio, Demian Levis, Leticia F. Cugliandolo, Giuseppe Gonnella

Published: 2020-05-14T11:56:41.000Z

## Abstract

As a result of nonequilibrium forces, purely repulsive self-propelled particles undergo macrophase 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 microphase 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 microdomains 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.

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## Original sources and implementation

[Original paper](<https://arxiv.org/abs/2005.06893>)

[PDF](<https://arxiv.org/pdf/2005.06893.pdf>)