Collective plasma response of interacting electrons localized in disordered GaAs/AlxGa1-xAs superlattices - art. no. 115311

The collective plasmon-LO phonon excitations were studied by Raman scatteri ng in intentionally disordered GaAs/AlGaAs superlattices with various stren gths of disorder. The results were compared with the data obtained in the d ifferently doped superlattices where the fixed disorder was mainly provided by the monolayer fluctuations of the layer thicknesses. Thus, the influenc es of both disorder and electron-electron interaction on the behavior of lo calized electrons were explored. We found that in the presence of disorder, the collective excitations tend to form coherently oscillating clusters wi th a finite extent. It was shown that while interaction causes the formatio n of coherent clusters, the effect of both the temperature and disorder is to destroy them; these evolutions of the clusters revealed a critical behav ior.