Dynamical self-assembly of dipolar active Brownian particles in two dimensions

Area of Science:

• Physics
• Soft Matter Physics
• Statistical Mechanics

Background:

• Active Brownian particles (ABPs) are model systems for self-propelled entities.
• Dipole-dipole interactions significantly influence the collective behavior of active matter.
• Understanding self-assembly in driven systems is crucial for designing novel materials.

Purpose of the Study:

• To investigate the dynamical self-assembly of active Brownian particles with dipole-dipole interactions.
• To characterize the phase behavior as a function of particle motility and dipolar coupling strength.
• To explore the emergence of flocking behavior in these systems.

Main Methods:

• Brownian Dynamics (BD) simulations were employed.
• A wide range of motilities and dipolar coupling strengths were explored.
• Order parameters were used to characterize system behavior.

Main Results:

• At low densities and motilities, particles aggregate into chains.
• Increasing motility leads to chain breaking and an isotropic fluid state.
• Dipolar coupling suppresses motility-induced phase separation, leading to flocking at high coupling strengths.

Conclusions:

• The interplay between motility and dipole-dipole interactions dictates self-assembly pathways.
• Flocking behavior emerges in active dipolar systems, distinct from passive systems.
• These findings offer insights into the design of self-organizing active matter.