High harmonics of the cyclotron resonance in microwave transmission of a high-mobility two-dimensional electron system

Abstract

We report an observation of magneto-oscillations in transmittance of the circularly polarized microwave radiation through the high-mobility two-dimensional electron system hosted by a GaAs quantum well. The oscillations reflect an enhanced absorption of radiation at high harmonics of the cyclotron resonance and follow simultaneously measured microwave-induced resistance oscillations (MIRO) in the DC transport. While the relative amplitude (up to 1%) of the transmittance oscillations appears to be small, they represent a significant (greater than 50%) modulation of the absorption coefficient. The analysis of obtained results demonstrates that the low-B decay, magnitude, and polarization dependence of the transmittance oscillations accurately follow the theory describing photon-assisted scattering between distant disorder-broadened Landau levels. The extracted sample parameters describe reasonably well the concurrently measured MIRO. Our results provide insight into the MIRO polarization immunity problem and demonstrate that high-precision transmission measurements can be a sensitive probe of high-frequency dissipative effects in high-mobility systems.