Weak-localization type description of conduction in the "anomalous" metallic state

Abstract

This paper is devoted to the temperature dependence of the resistivity in Si- MOS samples over the wide range of densities in the ``metallic phase&#39;&#39; (n>n_c) but not too close to the critical density n_c. Three domains of different behavior in ρ(T) are identified. These are: [i] quantum domain of `low-temperatures&#39;, where a logarithmic T-dependence of ρ(with $dρ/dT<0$) dominates; [ii] semi-classical domain of `high-temperatures&#39;, in which Drude resistivity strongly varies with T (with dρ/dT>0); and [ii] crossover between the former two, where a linear T-dependence dominates (with dρ/dT>0). In the crossover regime and at higher densities (n>20x10^{11}/cm^2), ρ(T) goes through a minimum at temperature T_{min}. Both the absolute value of T_{min} and its dependence on density are found to be in an agreement with the conventional weak-localization theory. For n smaller than \sim 20x10^{11}/cm^2, the theoretical estimate for T_{min} falls outside the experimentally accessible temperature range. This explains the absence of the minimum at these densities in the data. In total, over the two decades in the temperature (domains [ii] and [iii]), the two semiclassical effects mimic the metallic like transport properties. Our analysis shows that the behaviour of ρ(T) in the region of ρ<< h/e^2 can be described phenomenologically in terms of the conventional weak-localization theory.