Directed assembly of binary suspensions of magnetizable ellipsoids

Abstract

We investigate the effect of particle anisotropy and magnetic properties on the directed assembly of binary suspensions of magnetizable ellipsoids in a two-dimensional confinement. A suspension of paramagnetic spheres and diamagnetic ellipsoids in a superparamagnetic medium is subjected to a uniform magnetic field that is perpendicular to the assembly plane. We implement the ellipsoid-dipole model in a Monte-Carlo simulation to analyze the effects of particle aspect ratio, medium permeability, and relative particle concentrations on the assembly of binary suspensions of ellipsoids. We validate the simulations by comparing the orientational symmetry of binary structures of magnetizable spheres with previously reported experiments. Simulation results for a binary suspension of paramagnetic and diamagnetic spheres show structures with tunable orientational symmetry as medium permeability increases. Additionally, the results for the directed assembly of paramagnetic spheres and diamagnetic ellipsoids show tunable open-packed triangular enclosures and interconnected chain-like structures with different local order. The simulation results show the potential for customizing the assembled structures by tuning both medium and particle magnetic properties in binary colloidal suspensions.