(358c) Assembly of Janus Particles In Combined Electric and Magnetic Fields

Gold-capped Janus particles have been shown to assemble into staggered chains upon exposure to an AC electric field. The AC electric field causes the polarization of the metal caps resulting in a dipole that is positioned at the base of the cap and is aligned with the external electric field. The particles assume an orientation within the staggered chain in which the caps of two adjacent particles touch. Simulations show that this configuration allows for the energetically most favorable dipole-dipole interaction. Recently, we have prepared Janus particles with varying iron oxide caps. One of the iron oxides, Fe3O4, exhibits both conducting and magnetic properties. Exposure of the Fe3O4 Janus particles to a magnetic field leads to close-packed double chains, while staggered chains are formed in an AC electric field. This finding opens up the possibility to study chain dynamics, if conditions can be found in which the relative stability of the two minima can be varied through the external field strength. In this talk, we will report on the behavior of Fe3O4 capped Janus particles in the presence of combined electric and magnetic fields and present a simple model that explains it.