COLLECTIVE ELECTRONIC EXCITATIONS IN GAAS/ALXGA1-XAS QUANTUM-WELLS

We report calculations of intersubband spin- and charge-density excitations in quantum wells, using a nonlocal response formalism developed by us in earlier investigations of collective excitations in quantum-confined electron gases. Dispersion curves for these excitations are symmetrically displaced with respect to the single-particle continuum, indicating that direct Coulomb and exchange-correlation interactions have comparable strengths in GaAs/Al(x)Ga(1-x)As single-well heterostructures. The calculated results, which are based on the local-spin-density approximation for exchange and correlation, are in good agreement with inelastic-light-scattering experiments.