Elementary excitations in modulation-doped Cd(Mn)Te quantum wells - art. no. 161302

We report on the observation of dispersive elementary excitations of two-di mensional electron gases in modulation-doped CdTe and Cd1-xMnxTe quantum we lls. From the plasmon dispersion, we deduce electron densities in good agre ement with the ones deduced from independent experiments, provided that a f inite lifetime of the electron-hole pairs is taken into account within a mo dified random phase approximation model. We also find in the same samples u ncorrelated electron-hole excitations at energies significantly lower than expected from the electron density. We discuss the possible implications of these findings in terms of electron localization.