“…[3,4,5,6] This so-called zero resistance state (ZRS) has stimulated extensive theoretical interest. [7,8,9,10,11,12] At higher magnetic field ω c > ω a considerable decrease of magnetoresistance with microwave power is found [2,5,6] which has been attributed to intra-Landau-level transitions. [13] Another interesting nonlinear phenomena have been observed in response to DC electric field.…”