Quasiparticle interference in the spin-density wave phase of iron-based superconductors

TL;DR

This paper explains the quasiparticle interference patterns in iron-based superconductors' spin-density wave phase as a result of magnetic order interacting with electronic structure, predicting a transition from one-dimensional to two-dimensional QPI features.

Contribution

It provides a theoretical explanation linking magnetic SDW order with observed QPI patterns and predicts a dimensional crossover at a specific energy scale.

Findings

QPI patterns reflect SDW-related quasiparticle scattering

QPI exhibits a pronounced one-dimensional structure due to ellipticity and selective electron pocket involvement

A crossover to two-dimensional QPI occurs at an energy scale around 90 meV

Abstract

We propose an explanation for the electronic nematic state observed recently in parent iron-based superconductors [T.-M. Chuang et al., Science 327, 181 (2010)]. We argue that the quasi-one-dimensional nanostructure identified in the quasiparticle interference (QPI) is a consequence of the interplay of the magnetic ($\pi$, 0) spin-density wave (SDW) order with the underlying electronic structure. We show that the evolution of the QPI peaks largely reflects quasiparticle scattering between electronic bands involved in the SDW formation. Because of the ellipticity of the electron pocket and the fact that only one of the electron pockets is involved in the SDW, the resulting QPI has a pronounced one-dimensional structure. We further predict that the QPI crosses over to two-dimensionality on an energy scale, set by the SDW gap, which we estimate from neutron scattering data to be around 90 meV.