Phase behaviour and dynamical features of a two-dimensional binary mixture of active/passive spherical particles

TL;DR

This study investigates the phase behavior and dynamics of a two-dimensional mixture of active and passive particles, revealing how activity influences phase separation, structure formation, and particle diffusion.

Contribution

It provides new insights into how passive particles affect active matter phase behavior and how activity induces super-diffusive motion in passive particles.

Findings

Passive agents hinder phase separation.

Active agents promote crystal-like structures.

Active particles induce super-diffusive behavior in passive particles.

Abstract

In this work we have characterized the phase behaviour and the dynamics of bidimensional mixtures of active and passive Brownian particles. We have evaluated state diagrams at several concentrations of the passive components finding that, while passive agents tend to hinder phase separation, active agents force crystal-like structures on passive colloids. In order to study how passive particles affect the dynamics of the mixture, we have computed the long-time diffusion coefficient of each species, concluding that active particles induce activity and super-diffusive behaviour on passive ones. Interestingly, at the density at which the system enters a MIPS state the active particles' diffusivity shows an inflection point and the passive particles' one goes through a maximum, due to the change in the dynamics of the active components, as shown in the displacement's probability distribution function.