Active dipole clusters: From helical motion to fission.

Area of Science:

• Soft matter physics
• Active matter physics
• Colloidal science

Background:

• Particle cluster structure is typically determined by energy minimization.
• Active particles exhibit self-propulsion, leading to novel collective behaviors.
• Dipolar interactions play a crucial role in self-assembled structures.

Purpose of the Study:

• To investigate the dynamics and final structures of active soft-sphere dipole clusters.
• To explore how self-propulsion influences cluster morphology and motion.
• To understand the conditions leading to cluster fission versus stable states.

Main Methods:

• Numerical solution of overdamped equations of motion for soft-sphere dipoles.
• Simulation of systems with varying model parameters and self-propulsion activation protocols.
• Analysis of cluster center-of-mass motion and final structural configurations.

Main Results:

• Self-propulsion induces complex dynamics in metastable dipolar clusters, deviating from equilibrium structures.
• Cluster center-of-mass follows a helical path, influenced by initial magnetization.
• Cluster fission occurs with instantaneous self-propulsion increase, but is suppressed by slow activation.

Conclusions:

• Self-propelled dipoles exhibit rich emergent behaviors not seen in passive systems.
• Control over self-propulsion activation protocols allows tuning of cluster dynamics and morphology.
• Experimental verification is possible using colloidal Janus particles and macroscopic systems.