Quasi-one Dimensional Nanostructures as Sign of Nematicity in Iron Pnictides and Chalcogenides

TL;DR

This paper demonstrates that impurity-induced quasi-one dimensional modulations in the local density of states across various iron-based superconductors can be explained by a unified orbital symmetry breaking, indicating nematicity.

Contribution

It provides a unified explanation for quasi-one dimensional features in different phases of iron pnictides and chalcogenides through orbital splitting.

Findings

Impurity scattering causes quasi-one dimensional LDOS modulations.

A four-fold symmetry breaking orbital splitting explains these features.

The explanation applies across multiple phases, including nematic, paramagnetic, and superconducting states.

Abstract

Impurity scattering is found to lead to quasi-one dimensional nanoscale modulation of the local density of states in the iron pnictides and chalcogenides. This `quasiparticle interference' feature is remarkably similar across a wide variety of pnictide and chalcogenide phases, suggesting a common origin. We show that a unified understanding of the experiments can be obtained by simply invoking a four-fold symmetry breaking $d_{xz}-d_{yz}$ orbital splitting, of a magnitude already suggested by the experiments. This can explain the one-dimensional characteristics in the local density of states observed in the orthorhombic nematic, tetragonal paramagnetic, as well as the spin-density wave and superconducting states in these materials.