Effect of inhomogeneity on the transport in underdoped superconductors

摘要

The in-plane normal state resistivity of a variety of underdoped cuprates is analysed in terms of a percolation model where carriers tunnel between metallic islands distributed in an insulating background. Exponential laws of the form p = p(0)exp(T-0/T)(alpha) where the exponent a changes from 1/4 at low temperature to 1/2 at higher temperatures are found to fit accurately the experimental data. The results are shown to be consistent with superconducting islands of size < 100 A. and high T-c congruent to 100 K, together with larger islands in the normal state embedded in an insulating matrix. (c) 2005 Elsevier Ltd. All rights reserved.