Swarming of micron-sized hematite cubes in a rotating magnetic field – Experiments

Oksana Petrichenko (1) , Guntars Kitenbergs (1) , Martins Brics (1) , Emmanuelle Dubois (2) , Régine Perzynski (2) , Andrejs Cēbers (1)

1 MMML Lab
2 PHENIX - PHysicochimie des Electrolytes et Nanosystèmes InterfaciauX

Energy input by under-field rotation of particles drives the systems to emergent non-equilibrium states. Here we investigate the suspension of rotating magnetic cubes. Micron-sized hematite cubes are synthesized and observed microscopically. When exposed to a rotating magnetic field, they form rotating swarms that interact with each other like liquid droplets. We describe the swarming behaviour and its limits and characterize the swarm size and angular velocity dependence on the magnetic field strength and frequency. A quantitative agreement with a theoretical model is found for the angular velocity of swarms as a function of the field frequency.

Domaines: Physique [physics]; Chimie

Oksana Petrichenko, Guntars Kitenbergs, Martins Brics, Emmanuelle Dubois, Régine Perzynski, et al.. Swarming of micron-sized hematite cubes in a rotating magnetic field – Experiments. Journal of Magnetism and Magnetic Materials, 2020, 500, pp.166404. ⟨10.1016/j.jmmm.2020.166404⟩. ⟨hal-03039012⟩