Anharmonic behavior in Microwave-driven resistivity oscillations in Hall bars

We analyzed the magnetoresistivity of a two-dimensional electron system excited by microwave radiation in a regime of high intensities and low frequencies. In such a regime, recent experiments show that different features appear in the magnetoresistivity response which suggest an anharmonic behavior. These features consist mainly in distorted oscillations and new resonance peaks at the subharmonics of the cyclotron frequency. We follow the model of microwave-driven electron orbits motion which become anharmonic when the ratio of microwave intensity to microwave frequency is large enough.