Scaling laws, phase diagram, localized magnetic moments and Kondo effect in two-dimensional metals

Metallic properties in two-dimensional electron systems appear in different trends to asymptotes of non-zero conductivity sigma at zero temperature T. The spin interaction plays a crucial role in the metallic behavior, and in teractions with localized moments lead to a Kondo effect, but they do not d estroy the metal. Different scaling forms with one or two parameters are us ed to describe the dependence of sigma in different ranges of T and carrier concentration n(s). The two-parameter scaling form describes both the "Kon do metal" and the more conventional metal at all temperatures.