From flocking to glassiness in dense disordered polar Active Matter

TL;DR

This paper investigates how geometrical frustration, autonomous motion, and cooperation influence large-scale behaviors in dense active matter, revealing phase transitions from flocking to glassiness and the suppression of phase separation.

Contribution

It introduces a model combining key ingredients of active matter, demonstrating reentrant glass transitions and the impact of polar order on phase separation.

Findings

Active matter can form migratory bands or long-range order depending on density.

A reentrant glass transition is triggered by alignment interactions.

Polar order suppresses phase separation, leading to homogeneous disordered states.

Abstract

Living materials such as biological tissues or bacterial colonies are collections of heterogeneous entities of different sizes, capable of autonomous motion, and often capable of cooperating. Such a degree of complexity brings to collective motion on large scales. However, how the competition between geometrical frustration, autonomous motion, and the tendency to move cooperatively impact large-scale behavior remains an open question. We implement those three ingredients in a model of active matter and show that the system, in forming migratory patterns, can arrange in bands or develop long-range order, depending on the density of the system. We also show that the active material undergoes a reentrant glass transition triggered by the alignment interaction that typically causes only collective migratory motion. Finally, we observe that polar order destroys active phase separation, producing homogeneous, disordered moving configurations.