Abstract
We have studied the cyclotron decay time of a Landau-quantized two-dimensional electron gas as a function of temperature (0.4–100 K) at a fixed magnetic field () using terahertz time-domain spectroscopy in a gallium arsenide quantum well with a mobility of and a carrier concentration of . We find a cyclotron decay time that is limited by superradiant decay of the cyclotron ensemble and a temperature dependence that may result from both dissipative processes as well as a decrease in below . Shubnikov–de Haas characterization determines a quantum lifetime, , which is significantly faster than the corresponding dephasing time, , in our cyclotron data. This is consistent with small-angle scattering as the dominant contribution in this sample, where scattering angles below do not efficiently contribute to dephasing. Above , the cyclotron oscillations show a strong reduction in both the oscillation amplitude and lifetime that result from polar optical phonon scattering.
- Received 2 July 2015
- Revised 29 March 2016
DOI:https://doi.org/10.1103/PhysRevB.93.155437
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