  We show that ratchet effects can occur in a glassy media of interacting
particles where there is no quenched substrate. We consider simulations of a
disordered binary assembly of colloids in which only one species responds to a
drive. We apply an asymmetric ac drive that would produce no net dc drift of an
isolated overdamped particle. When interacting particles are present, the
asymmetric ac drive produces a ratchet effect. A simple model captures many of
the results from simulations, including flux reversals as a function of density
and temperature.
