Biological & Soft Matter Seminar: Bidirectional currents in confined driven colloids
Dr. Antonio Ortiz-Ambriz, University of Barcelona, Spain
It is well known that matter behaves differently in confined spaces. One example of this is the equilibrium phases of core softened potential particles, which can be realized by confining magnetic particles in slit pores thick enough to accommodate one but not two particles.
I will discuss the rich behavior that appears from experimentally bringing a similar system out of equilibrium by adding a dynamic magnetic field. With this strategy, we can assemble the system in particle pairs, which can be made to rotate synchronously or asynchronously, or we can obtain buckled phases with soft potentials. By adjusting the packing fraction, an intermediate state can be induced in which particle pairs are broken and reassembled with other particles in a continuous exchange of neighbors. By adding a small in-plane component, this exchange process can be harnessed to produce a “ceilidh”-like bidirectional current with particle transport in a state that is reminiscent of skipping orbits in electronic and molecular systems.
We use Brownian dynamics simulations to show that this induced current is due only to the dipolar interaction, and we develop a theoretical model that shows two separate transport mechanisms which show excellent agreement with the simulations