INTERACTION COUPLED CYCLOTRON TRANSITIONS OF 2-DIMENSIONAL ELECTRON-SYSTEMS IN GAAS AT HIGH-TEMPERATURES

We report here the first observation of the cyclotron resonance Landau splitting for low density electron inversion layers in AlxGa1-xAs-GaAs heterojunctions. Even at temperatures close to 100 K electron-electron interactions couple the electrical dipole transitions from the ground and first excited Landau levels, with a coupling strength comparable to the one found at liquid helium temperatures. The experiment can be explained only in a single-particle approximation at sufficiently low densities and/or magnetic field strengths where the resonant polaron effect is important.