Magnetoplasma effects in a quasi-three-dimensional electron gas

Far-infrared measurements are carried out on a quasi-three-dimensional electron gas. In the absence of magnetic field the electrons are confined in a wide quantum well. When a high magnetic field is applied in the plane of the sample the electron gas undergoes a transition from two- to three-dimensional behavior. In the Voigt geometry, plasma shifted cyclotron resonances are observed as a consequence of such a transition. In the Faraday geometry a giant depolarization shift is observed on the optical intersubband transition and it represents the three-dimensional limit of this two-dimensional effect.