Logarithmic and power law corrections in two-dimensional electronic transport

The temperature dependence of conduction in Si inversion layers has been measured down to approximately 100 mK for a wide range of kFl. It is shown that the logarithmic decrease in sigma with decreasing temperature goes over at low kFl to a power law behaviour, as has been predicted. The decrease can be sufficiently great for the conductance to be reduced below sigma min( approximately=0.1 e2/h(cross)), and this regime can be distinguished from hopping by its negative magnetoresistance arising from the magnetic-field-induced decrease in length scale.