Cyclotron Resonance in a Two-Dimensional Electron Gas with Long-Range Randomness

We show that the cyclotron resonance in a two-dimensional electron gas has nontrivial properties if the correlation length of the disorder is larger than the Fermi wavelength: (a) The line shape assumes three different forms in strong, intermediate, and weak magnetic fields. (b) The linewidth collapses at the transition from the intermediate to the weak fields via the motional narrowing mechanism brought about by a dramatic enhancement of the localization length. copyright 1998 The American Physical Society