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Fluidization Induced by Magnetic Interactions in Confined Active Matter
Marco Musacchio1,2, Markus Felber3, Matteo Paoluzzi1
1Sapienza Università di Roma, Dipartimento di Fisica, Piazzale A. Moro 2, I-00185, Rome, Italy.
Physical Review. E
|June 19, 2026
Summary
Magnetic active matter in confined spaces shows less clustering due to magnetic interactions. These interactions also lead to novel collective behaviors like train formations and rotating clusters.
Area of Science:
- Physics
- Soft Matter Physics
- Complex Systems
Background:
- Active matter systems, like self-propelled particles, often exhibit boundary accumulation and clustering even at low densities.
- Confined geometries can significantly alter the emergent behaviors of active matter.
Purpose of the Study:
- To investigate the influence of magnetic interactions on active matter behavior in confined geometries.
- To explore how magnetic forces affect particle clustering and collective motion.
Main Methods:
- Experiments utilizing magnetic toy robots (Hexbugs).
- Simulations of elongated magnetic active Brownian particles within circular domains.
Main Results:
- Magnetic interactions induce a fluidization effect, delaying particle clustering to higher densities.
- Observed collective behaviors include train-like formations, rotating pairs, and rotating clusters.
- Standard active particles showed typical boundary accumulation and clustering.
Conclusions:
- Magnetic interactions can suppress clustering in confined active matter systems.
- Dipolar magnetic forces promote unique collective phenomena not seen in non-magnetic active matter.
- Confined magnetic active matter offers a tunable platform for studying complex emergent behaviors.
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