The observation of interaction and localisation effects in a two-dimensional electron gas at low temperatures

Abstract

The authors have investigated the logarithmic regime of transport of the two-dimensional electron gas in the Si inversion layer between 0.05K and 1K. There was little band tailing in the specimens used, and it was possible to achieve the k_Fl_EL approximately 1 condition at carrier concentrations as low as approximately 2*10¹⁵ m^-2. The behaviours of the conductance and the Hall effect suggest that in the presence of a magnetic field the logarithmic corrections are caused by electron-electron interaction. In particular, the authors confirm the prediction of this theory that the Hall coefficient varies at twice the rate of the resistance. However, at low values of magnetic field it appears that the transport behaviour arises from localisation rather than interactions. At particular values of magnetic field these two mechanisms are both present, but have a different stability against an increase in temperature. Consequently, at a constant lattice temperature it is possible to observe a transition between them as the electron temperature is increased with an electric field.