Analysis of Cyclotron Resonance Spectroscopy in a Landau-quantized 2DEG using Characteristic Matrix Methods*

We develop a new characteristic matrix-based method to analyze cyclotron resonance experiments in high mobility ($\mu_e = 3.7 \times 10^6 ~\mathrm{cm}^2~\mathrm{V}^{-1} ~\mathrm{s}^{-1}$) two-dimensional electron gas samples where direct interference between primary and satellite reflections has previously limited the frequency resolution. We use terahertz time-domain spectroscopy to measure the cyclotron resonance and extract the dephasing lifetime where multiple pulses from the substrate with a separation of $\sim 15$ ps directly interfere in the time-domain. We find a cyclotron dephasing lifetime of $15.1\pm 0.5$ ps at 1.5 K and $5.0\pm 0.5$ ps at 75 K.