Circular-polarization-dependent study of the microwave-induced magneto-resistance oscillations in the 2D electron system

We have investigated the influence of the polarization of the incident radiation on the recently discovered microwave-induced resistance oscillations in state-of-the-art highest purity 2D electron systems. A quasi-optical setup allows us to tune in situ between different circular as well as linear polarization states. We find that the microwave-induced zero resistance and the resistance oscillations are notably immune to changes in the polarization. This observation is discrepant with a number of proposed theories. Deviations for different polarizations only occur for a bolometric contribution to the resistance associated with the resonant heating at the cyclotron resonance itself.