Robust $s_{\pm}$-wave superconductivity against multi-impurity in iron-based superconductors

TL;DR

This study systematically investigates how disorder from multiple impurities affects the robustness of $s_{}$-wave superconductivity in iron-based superconductors, revealing resilience to weak impurities and vulnerability to strong ones.

Contribution

It provides a detailed analysis of impurity effects on superconducting and magnetic orders using self-consistent Bogoliubov-de Gennes equations, highlighting the differing sensitivities.

Findings

Weak scattering potentials do not qualitatively change the order parameters even at high impurity concentrations.

Strong scattering potentials easily suppress the superconducting order parameters.

Magnetic order is more sensitive to impurities than superconducting order, with spin density wave patterns destroyed before superconductivity is lost.

Abstract

Effects of disorder on electron-doped iron pnictides are investigated systematically based on self-consistent Bogoliubov-de Gennes equations. Multiply impurities with same scattering potential (SP) are randomly distributed in a square lattice. Probability distribution functions of normalized order parameters for different impurity concentrations $\delta_{imp}$, different electron doping concentrations $\delta$ are investigated for given SPs. Samples are found to be very robust against weak SP, in which order parameters do not have qualitative change even at very large $\delta_{imp}$. While strong SP is able to easily break down the order parameters. For moderate SP, variations of order parameters on and around impurities strongly depend on $\delta$, however the distribution functions of normalized order parameters have similar behavior as $\delta_{imp}$ increases. Compared with superconducting (SC) order, the magnetic order is more sensitive to multi-impurity effect. The spatial spin density wave pattern has already been destroyed before the system loses its superconductivity. Dependence of SC order on temperature is similar to that of impurity-free case, with the critical temperature being remarkably suppressed for high $\delta_{imp}$.