Non-linear transport phenomena in a two-subband system
  We study non-linear transport phenomena in a high-mobility bilayer system with two closely spaced populated electronic subbands in a perpendicular magnetic field. For a moderate direct current excitation, we observe zero-differential-resistance states with a characteristic 1/B periodicity. We investigate, both experimentally and theoretically, the Hall field-induced resistance oscillations which modulate the high-frequency magneto-intersubband oscillations in our system if we increase the current. We also observe and describe the influence of direct current on the magnetoresistance in the presence of microwave irradiation. 
S. Wiedmann, G. M. Gusev, O. E. Raichev, A. K. Bakarov, and J. C.   Portal
cond-mat.mes-hall