Quasiparticle Scattering Interference in Superconducting Iron-pnictides

TL;DR

This study investigates quasiparticle interference patterns in iron-based superconductors using multi-orbital models, revealing how impurity types and pairing symmetries influence observable QPI features, thus aiding in identifying pairing mechanisms.

Contribution

It provides a comparative analysis of QPI patterns in different orbital models and pairing symmetries, highlighting their potential to reveal band structures and pairing symmetry in superconductors.

Findings

QPI patterns depend on band structure and impurity type.

Peaks near (±π,0) and (0,±π) are sensitive to impurity and pairing symmetry.

QPI can serve as a probe for pairing symmetry and band structure.

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 $\cos(k_x)\cdot\cos(k_y)$ and sign-unchanged $|\cos(k_x)\cdot\cos(k_y)|$ SC states. While the patterns strongly depend on the chosen band structures, the sensitivity of peaks around $(\pm\pi,0)$ and $(0,\pm\pi)$ wavevectors on magnetic or non-magnetic impurity, and sign change or sign unchanged SC orders is common in two models. Our results strongly suggest that QPI may provide direct information of band structures and evidence of the pairing symmetry in the SC states.