  We consider a two dimensional colloidal dispersion of soft-core particles
driven by a one dimensional stochastic flashing ratchet that induces a time
averaged directed particle current through the system. It undergoes a
non-equilibrium melting transition as the directed current approaches a maximum
associated with a resonance of the ratcheting frequency with the relaxation
frequency of the system. We use extensive molecular dynamics simulations to
present a detailed phase diagram in the ratcheting rate-mean density plane.
With the help of numerically calculated structure factor, solid and hexatic
order parameters, and pair correlation functions, we show that the
non-equilibrium melting is a continuous transition from a quasi-long ranged
ordered solid to a hexatic phase. The transition is mediated by the unbinding
of dislocations, and formation of compact and string-like defect clusters.
