Circular-polarization independence of microwave-induced resistance oscillations and the zero-resistance state

The immunity of microwave-induced magnetoresistance oscillations and corresponding zero resistance regions to the direction of (circular) polarization of microwaves is studied in this paper. We propose that a spontaneous circular motion of the whole electron fluid would stabilize the system and minimize the polarization sensitivity of the oscillatory dc resistance. Results of a self-consistent calculation capture the qualitative features of the experimental observation.