随机环境中运动诱导相分离的活化粗化

中文摘要 AI 辅助

仅相互排斥的自推进粒子仍能分离成稠密相和稀薄相，这一过程被称为运动诱导相分离（MIPS）。在干净系统中，畴的粗化行为与任何守恒混合物相同：畴尺寸按 $\ell(t)\sim t^{1/3}$ 增长。然而，活性游泳体和合成游泳体在粗糙、多孔或图案化的环境中运动。通过活性布朗粒子的大规模模拟，我们探究冻结异质性如何改变MIPS的粗化行为。我们以两种方式引入无序：一种是对粒子位置作用的淬火随机力场，另一种是对粒子取向作用的淬火随机力矩场。两者都破坏了Lifshitz-Slyozov增长。具有无序依赖指数的瞬态幂律让位于活化动力学，其中有效动力学指数无界增长，畴尺寸至多呈对数增长。交叉行为遵循从随机场伊辛模型中已知的标度形式，且畴形态取决于无序强度，因此超普适性失效。这两种无序通过不同机制起作用。当漂移超过自推进时，随机力将粒子捕获在随机漂移场的汇点中。随机力矩则表现为符号随机的淬火手性，削弱持久性并将局部Péclet数降至其临界值附近。我们的结果表明，淬火无序是活性相分离动力学的相关微扰，并将MIPS粗化与无序磁体中钉扎界面的物理联系起来。

英文摘要

Self-propelled particles that only repel one another can still separate into a dense and a dilute phase, a process known as motility-induced phase separation (MIPS). In a clean system the domains coarsen like any conserved mixture: domains grow as $\ell(t)\sim t^{1/3}$. Living and synthetic swimmers, however, move through rough, porous, or patterned surroundings. Using large-scale simulations of active Brownian particles, we ask how frozen heterogeneity changes MIPS coarsening. We introduce disorder in two ways, as a quenched random force field acting on particle positions and as a quenched random torque field acting on their orientations. Both destroy Lifshitz-Slyozov growth. A transient power law with a disorder-dependent exponent gives way to activated dynamics in which the effective dynamic exponent grows without bound and domains grow at most logarithmically. The crossover obeys the scaling form known from the random-field Ising model, and the domain morphology depends on disorder strength, so superuniversality fails. The two kinds of disorder act through different mechanisms. Random forces trap particles in the sinks of a random drift field once the drift beats self-propulsion. Random torques act as a sign-random, quenched chirality that erodes persistence and lowers the local Péclet number toward its critical value. Our results show that quenched disorder is a relevant perturbation for the kinetics of active phase separation and connect MIPS coarsening to the physics of pinned interfaces in disordered magnets.

发表机构

• Vellore Institute of Technology（维洛尔理工学院）
• Indian Institute of Science Education and Research Berhampur（贝赫拉姆印度科学教育研究所）

机构由 AI 辅助整理，请以论文原文为准。