Publication in Physical Review Letters
Directional locking is observed when a colloidal monolayer is driven across and interacts with a triangular lattice of magnetic bubbles.
News from Feb 04, 2020
We investigate the directional locking effects that arise when a monolayer of paramagnetic colloidal particles is driven across a triangular lattice of magnetic bubbles. We use an external rotating magnetic field to generate a two-dimensional traveling wave ratchet forcing the transport of particles along a direction that intersects two crystallographic axes of the lattice. We find that, while single particles show no preferred direction, collective effects induce transversal current and directional locking at high density via a spontaneous symmetry breaking. The colloidal current may be polarized via an additional bias field that makes one transport direction energetically preferred.
R. L. Stoop, A. V. Straube, T. H. Johansen, and P. Tierno, Collective Directional Locking of Colloidal Monolayers on a Periodic Substrate, Phys. Rev. Lett. 124, 058002 (2020)