  We observe the phonon-drag voltage oscillations correlating with the
resistance oscillations under microwave irradiation in a two-dimensional
electron gas in perpendicular magnetic field. This phenomenon is explained by
the influence of dissipative resistivity modified by microwaves on the
phonon-drag voltage perpendicular to the phonon flux. When the lowest-order
resistance minima evolve into zero-resistance states, the phonon-drag voltage
demonstrates sharp features suggesting that current domains associated with
these states can exist in the absence of external dc driving.
