Fluidization Induced by Magnetic Interactions in Confined Active Matter

We investigate magnetic active matter in confined geometries using both experiments with magnetic toy robots, Hexbugs, and simulations of elongated magnetic active Brownian particles in circular domains. Standard active particles tend to accumulate at boundaries, forming clusters even at relatively low densities. In the presence of magnetic interactions, we provide evidence for a fluidization effect that inhibits clustering and shifts its onset to higher packing fractions. Moreover, magnetic dipolar interactions give rise to collective behaviors such as train-like formations, rotating pairs, and rotating clusters.