Wake-induced symmetry-breaking of dust particle arrangements in a complex plasma

A symmetry-breaking disruption occurs in a system of two dust particles with the decrease of the particle separation. This disruption is attributed to the formation of the common ion wake in the system. In the experiment, the particles levitate in the sheath of a radio-frequency (rf) discharge at low gas pressures ($\leq 60$ mTorr) and their separation is changed by the laser manipulation. The experiment is complemented by molecular dynamics (MD) numerical simulations. The experimental and simulation data agree that the disruption condition corresponds to the common ion wake formation at the interparticle distances less than the electron Debye length.