Resonant Subband Landau Level Coupling in the Wide Quantum Well

Subband energies and intersubband couplings in an ultra high-mobility GaAs/Al{\_}{\{}0.24{\}}Ga{\_}{\{}0.76{\}}As wide quantum well have been investigated by magneto-infrared spectroscopy. In this ultra clean and symmetric wide quantum well, couplings between the 1st and up to the 4th electric subbands have been observed, including a symmetry-forbidden coupling between the 1st and 3rd subbands. The results can be interpreted in terms of the magnetoplasma coupling in a quasi-three-dimensional system or the resonant subband Landau level coupling with a slab plasma frequency dependent depolarization shift in a two-dimensional system. The latter appears to be a better interpretation for the observed anticrossings in this system.