Suppression of $T_c$ by Zn impurity in the electron-type LaFe$_{0.925-y}$Co$_{0.075}$Zn$_y$AsO system

TL;DR

This study systematically investigates how non-magnetic Zn impurity suppresses superconductivity in LaFeCoAsO, supporting the $s_{}$ pairing scenario and contrasting previous findings in F-doped systems.

Contribution

It provides experimental evidence on the suppression of $T_c$ by Zn impurity in LaFeCoAsO, aligning with $s_{}$ pairing theory and highlighting differences from F-doped systems.

Findings

Zn impurity severely suppresses $T_c$ in LaFeCoAsO

Results support $s_{}$ pairing symmetry

Contrasts with previous reports on F-doped systems

Abstract

The effect of non-magnetic Zn impurity on superconductivity in electron-type pnictide superconductor LaFe$_{0.925-y}$Co$_{0.075}$Zn$_y$AsO is studied systematically. The optimally doped LaFe$_{0.925}$Co$_{0.075}$AsO without Zn impurity exhibits superconductivity at $T_c^{mid}$ of 13.2 K, where $T_c^{mid}$ is defiend as the mid-point in the resistive transition. In the presence of Zn impurity, the superconducting transition temperature, $T_c^{mid}$, is severely suppressed. The result is consistent with the theoretic prediction on the effect of non-magnetic impurity in the scenario of $s_{\pm}$ pairing, but it is in sharp contrast to the previous report on the effect of Zn impurity in the F-doped systems. The possible interpretation of the different effects of Zn impurity on superconductivity in different systems is discussed.