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-GaA s heterojunctions. Even at temperatures close to 100 K electron-electr on interactions couple the electrical dipole transitions from the grou nd and first excited Landau levels, with a coupling strength comparabl e to the one found at liquid helium temperatures. The experiment can b e explained only in a single-particle approximation at sufficiently lo w densities and/or magnetic field strengths where the resonant polaron effect is important.