Melting of a two dimensional crystal driven far from equilibrium*

Particles confined to a 2D interface interacting with a repulsive dipolar interaction are known to form crystals that melt through 2 stages via the Kosterlitz-Thouless-Halperin-Nelson-Young mechanism of defect unbinding. Here we are interested in how the crystal melts when defects are created by activity. We explore this question by introducing a small fraction of magnetic spinners to our system of charged particles confined to a water-oil interface. The hydrophobic charged particles interact in the oil phase while the magnetic spinners sit directly below them on lattice sites in the aqueous phase. The spinning particles drive their neighbors orbitally and induce the creation of disclinations and dislocations which melt the lattice. We study and contrast this active melting process with thermodynamic melting.