Quasiparticle scattering interference in superconducting iron pnictides

Abstract

Using both two orbital and five orbital models, we investigate the quasiparticle interference (QPI) patterns in the superconducting (SC) state of iron-based superconductors. We compare the results for nonmagnetic and magnetic impurities in sign-changed $s$-wave $\text{cos}({k}_{x})\ensuremath{\cdot}\text{cos}({k}_{y})$ and sign-unchanged $|\text{cos}({k}_{x})\ensuremath{\cdot}\text{cos}({k}_{y})|$ SC states. While the patterns strongly depend on the chosen band structure details, the sensitivity of peaks around $(\ifmmode\pm\else\textpm\fi{}\ensuremath{\pi},0)$ and $(0,\ifmmode\pm\else\textpm\fi{}\ensuremath{\pi})$ wave vectors on magnetic or nonmagnetic impurities, and on sign-changed or sign-unchanged SC orders is a common feature. Our results suggest that the QPI can provide evidence of the pairing symmetry in the SC states.