Effect of Zn doping in under- and over-doped LaFe1-xCoxAsO system

We study the effect of nonmagnetic Zn impurity on superconductivity in the Co-doped LaFe1-x-yCoxZnyAsO system. A light Zn doping drastically suppresses the superconducting transition temperature T-c(mid) for both under-and over-doped superconductors. This is consistent with the theoretical prediction within the scenario of s +/--wave or d-wave pairings. The rate of the T-c decrease, vertical bar dT(c)/dy vertical bar, is substantially smaller in the under-doped regime than in the over-doped regime. We propose that the less drastic T-c reduction in the under-doped superconductor is due to the suppression of a competing antiferromagnetic order, which is in favor of superconductivity. Copyright (C) EPLA, 2013