Structure and tracer-diffusion in quasi two-dimensional and strongly asymmetric magnetic colloidal mixtures

We study theoretically and experimentally static and diffusional properties of a strongly asymmetric binary mixture of super-paramagnetic colloids confined to an air-water interface. The colloids interact via repulsive dipolar forces, induced by a magnetic field applied perpendicular to the planar interface. Brownian dynamics ( BD) computer simulations are employed to analyse the microstructure and the tracer-diffusion of both components. The profound interaction asymmetry leads to unusual features in the partial pair distribution functions, and to significantly enhanced tracer-diffusion. We find good agreement between our experimental data and the computer simulation results.