Sommaire:

We study the metal-insulator transition in a narrow impurity band with small degree of disorder. The critical concentration is shown to be lower than predicted by the Mott-Anderson criterion. As a result, a band of delocalized states appears in the middle of the impurity band. However, the Fermi level lies below the band of delocalized states. Thus, at low temperatures the transport is due to activation from the Fermi level.  The theory is in agreement with experimental data for AlGaAs/GaAs quantum wells.
We also explain the breakdown behavior observed experimentally. The concept of the virtual Anderson transition allows to explain ferromagnetism observed in AlGaAs/GaAs structures, doped with Mn at very low concentrations.

Pour plus d'informations, merci de contacter Dyakonov M.