Argonne National Laboratory

Research Highlight | Materials Science

Chirality-switching vortices in active roller swarms
In a study published in Nature Communications, researchers demonstrate the potential of magnetic roller vortices to effectively capture and transport inert particles at the microscale.
Chirality switching statistics of a roller vortex. a Chirality switching events illustrated by the polar order parameter of a roller vortex formed in a soft harmonic gravitational confinement. B0 = 5.78 mT, fB = 40 Hz. b Events of the flock intermittency not resulted in a roller vortex chirality switch. c Probability distribution functions for the roller vortex to have no chirality switching events (P0) or have one successful chirality change (P1). Error bars are the standard deviation of the measurements.

Scientific Achievement

We have identified emergence of macroscopic vortices not relying on geometrical confinements in ensembles of active magnetic rollers, leading to spontaneous switching of a vortex’s sense of rotation and to capture and transport of inert cargo particles.

Significance and Impact

Our work exposes the behavior of active roller liquids capable of complex collective behavior, suggesting new pathways for the design and control of microscale tunable transport in active materials.

Research Details

  • Magnetic rollers emerge due to spontaneous uniaxial field-induced chirality breaking
  • Rollers couple spinning and translational activities
  • Unconfined roller vortices have an ability to traverse the surface

DOI: 10.1038/s41467-018-04765-w

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