We present an interpretation of recent cyclotron resonance experiments on the two-dimensional electron gas in GaAs/AlGaAs heterostructures. We show that the observed dependence of the resonance spectrum on Landau level occupancy and temperature arises from the interplay of three factors: spin-splitting of the cyclotron frequency; thermal population of the two spin states; and coupling of the resonances for each spin orientation by Coulomb interactions. In addition, we derive an f-sum rule which allows spin polarisation to be determined directly from resonance spectra.
@article{arxiv.cond-mat/9401049,
title = {Theory of Spin-Split Cyclotron Resonance in the Extreme Quantum Limit},
author = {N. R. Cooper and J. T. Chalker},
journal= {arXiv preprint arXiv:cond-mat/9401049},
year = {2011}
}