Structure formation in a binary monolayer of dipolar particles.

We propose an experimental technique for an easy to control realization of a binary dipolar monolayer where the two components have oppositely oriented dipole moments constrained perpendicular to the plane of motion without the application of an external field. The experimental setup ensures that hydrodynamic effects do not play a crucial role in the structure formation, the particles move deterministically due to the dipole-dipole interaction. At low concentrations, cluster-cluster aggregation occurs with chainlike morphologies, while at high concentration the particles self-assemble into various types of binary crystal lattices, in good agreement with the theoretical predictions. The structures formed by the particles are found to be sensitive to external perturbations due to the central interparticle forces, however, static friction arising at the contact surface of particles can increase the stability compared to systems with only viscous friction.