Effect of a Zn impurity on Tcand its implications for pairing symmetry in LaFeAsO1-XFX

Abstract

The effect of a non-magnetic Zn impurity on superconductivity in the LaFe1-yZnyAsO1-xFx system is studied systematically. In the presence of a Zn impurity, the superconducting (SC) transition temperature increases in the under-doped regime, remains unchanged in the optimally doped regime and is severely suppressed in the over-doped regime. Our results suggest a switch in the symmetry of the SC order parameters from an s-wave to s±- or d-wave states as the charge carrier doping increases in FeAs-based superconductors. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.