Direct Measurement of Cyclotron Coherence Times of High-Mobility Two-Dimensional Electron Gases

摘要

We have observed long-lived (~30 ps) coherent oscillations of charge carriersdue to cyclotron resonance (CR) in high-mobility two-dimensional electrons inGaAs in perpendicular magnetic fields using time-domain terahertz spectroscopy.The observed coherent oscillations were fitted well by sinusoids withexponentially-decaying amplitudes, through which we were able to provide directand precise measures for the decay times and oscillation frequenciessimultaneously. This method thus overcomes the CR saturation effect, which isknown to prevent determination of true CR linewidths in high-mobility electronsystems using Fourier-transform infrared spectroscopy.