Direct and indirect magnetoexcitons in symmetric InxGa1-xAs/GaAs coupled quantum wells

Spatially direct (intrawell) and indirect (interwell) excitons in symmetric InxGa1-xAs/GaAs coupled quantum wells were studied by photoluminescence and photoluminescence excitation spectroscopy at magnetic fields B≤14 T. The regimes of zero and high electric fields in the growth direction as well as the transition between them were examined. The magnetic field changes the ratio between the one-particle symmetric-antisymmetric splittings and the exciton binding energies. This was found to result in a strong influence on the energies and oscillator strengths of the optical transitions both at zero and finite electric fields. The direct-indirect exciton crossover under applied electric field was found to be markedly modified by the magnetic field due to the increase of the exciton binding energy.