Many-body effects on the cyclotron resonance in a two-dimensional electron gas

We consider optical absorption by an interacting two-dimensional electron system, with impurities, in a strong perpendicular magnetic field, at electron densities such that an integral number of Landau levels is filled. The Coulomb energy e2/εl0 is assumed to be smaller than the cyclotron energy ħωc, and correlation effects are treated exactly to lowest order in (e2/εl0)/ħωc. The impurity scattering is treated in a self-consistent approximation for several different impurity potentials. The cyclotron resonance line is found to be significantly altered by electron-electron interactions. The line is shifted to lower frequencies and a line narrowing due to correlation effects is found.