Two-Dimensional Metal: Lack of Universal One-Parameter Scaling and Logarithmic Correction to the Conductivity

Abstract

We show that the two-dimensional metallic state in Si-MOS samples persists over a wide range of temperatures (16mK to 8K), sample peak mobilities (varying by a factor of 8), carrier densities (0.7 to 35x10^{11}cm^{-2}) and conductances ranging from 0.3 to 115 e^2/h. Our data reveal a failure of the universal one-parameter scaling. We have found a weak logarithmic correction to the conductivity, which is of delocalizing sign and drives the system towards zero resistance at T=0K.