Calculations for an inhomogeneous d-wave superconductor

We calculate the distributions P[Delta(0)(r(i))] of local d-wave pairing amplitude Delta(0)(r(i)) at a position r(i) inside a disordered high-temperature superconductor (HTS) family. To reproduce the observed inhomogeneity a random potential V-imp, within a Bogoliubov-deGennes (BdG) formalism, is considered. We perform calculations with fixed values of the disorder strength V-imp obtaining the distribution of Delta(0)(r(i)), and local density of charge carriers rho(r(i)), for different compounds of the LSCO family. The calculation of the relative rootmean-square deviation shows that the underdoped compounds are more inhomogeneous than the overdoped ones. Also, the spatial variation of Delta(0)(r(i)) decreases as the average density of charge carriers < p > increases, demonstrating that the compounds are more homogeneous for high values of < p >. The results indicate that the d-wave superconducting gaps seem to be more sensitive to a change in the disorder in comparison with the s-wave superconducting gaps. (C) 2007 Elsevier B.V. All rights reserved.