Quasiparticle interference in iron-based superconductors

TL;DR

This paper systematically analyzes quasiparticle interference signatures across the phase diagram of iron-based superconductors, revealing how impurity effects and ordered phases influence spectroscopic imaging results and providing insights into the superconducting order parameter symmetry.

Contribution

It offers a comprehensive calculation of QPI signatures for all phases of iron-based superconductors, highlighting impurity effects and symmetry verification methods.

Findings

Distinct QPI features in different phases

Impurity scattering distinguishes s+- symmetry

Signatures of gap minima or nodes discussed

Abstract

We systematically calculate quasiparticle interference (QPI) signatures for the whole phase diagram of iron-based superconductors. Impurities inherent in the sample together with ordered phases lead to distinct features in the QPI images that are believed to be measured in spectroscopic imaging-scanning tunneling microscopy (SI-STM). In the spin-density wave phase the rotational symmetry of the electronic structure is broken, signatures of which are also seen in the coexistence regime with both superconducting and magnetic order. In the superconducting regime we show how the different scattering behavior for magnetic and non-magnetic impurities allows to verify the $s^{+-}$ symmetry of the order parameter. The effect of possible gap minima or nodes is discussed.