Nonmagnetic pair-breaking effect in La(Fe_{1-x}Zn_{x})AsO_{0.85} studied by ^{75}As and ^{139}La NMR and NQR

Abstract

^{75}As and ^{139}La NMR and nuclear quadrupole resonance (NQR) studies on Zn-substituted LaFeAsO_{0.85} have been performed to microscopically investigate the Zn-impurity effects. Although superconductivity in LaFeAsO_{0.85} disappears by 3% Zn substitution, we found that NMR/NQR spectra and NMR physical quantities in the normal state are hardly changed, indicating that the crystal structure and electronic states are not modified by Zn substitution. Our results suggest that the suppression of superconductivity by Zn substitution is not due to the change of the normal-state properties, but due to strong nonmagnetic pair-breaking effect to superconductivity.