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

TL;DR

This paper demonstrates a method to directly measure cyclotron coherence times in high-mobility two-dimensional electron gases using time-domain terahertz spectroscopy, overcoming previous limitations of Fourier-transform infrared spectroscopy.

Contribution

It introduces a novel time-domain approach for accurately measuring cyclotron resonance decay times in high-mobility electron systems.

Findings

Measured charge carrier oscillations lasting ~30 ps

Provided direct, precise decay times and frequencies

Overcame CR saturation limitations of previous methods

Abstract

We have observed long-lived (~30 ps) coherent oscillations of charge carriers due to cyclotron resonance (CR) in high-mobility two-dimensional electrons in GaAs in perpendicular magnetic fields using time-domain terahertz spectroscopy. The observed coherent oscillations were fitted well by sinusoids with exponentially-decaying amplitudes, through which we were able to provide direct and precise measures for the decay times and oscillation frequencies simultaneously. This method thus overcomes the CR saturation effect, which is known to prevent determination of true CR linewidths in high-mobility electron systems using Fourier-transform infrared spectroscopy.