  We analyze theoretically the oscillations that the magnetoresistivity of
two-dimensional electron systems present when a high intensity direct current
is applied. In the model presented here we suggest that a plasma wave is
excited in the system producing an oscillating motion of the whole
two-dimensional electron gas at the plasma frequency. This scenario affects
dramatically the way that electrons interact with scatterers giving rise to
oscillations in the longitudinal resistivity. With this theoretical model
experimental results are well reproduced and explained.
