Coherence Length of Electronic Nematicity in Iron-Based Superconductors

TL;DR

This study investigates the coherence length of electronic nematicity in iron-based superconductors, revealing its variation across materials and its correlation with non-Fermi liquid behavior and spin-orbital fluctuations.

Contribution

It demonstrates that the nematic coherence length varies among different iron-based superconductors and links this variation to underlying spin-orbital fluctuations affecting transport properties.

Findings

Longer nematic domain walls in FeSe$_{0.9}$S$_{0.1}$ and mesoscopic nematicity wave formation.

Shorter domain walls in undoped BaFe$_2$As$_2$.

Correlation between domain wall thickness and non-Fermi liquid resistivity behavior.

Abstract

Recent developments in laser-excited photoemission electron microscopy (laser-PEEM) advance the visualization of electronic nematicity and nematic domain structures in iron-based superconductors. In FeSe and BaFe$_2$(As$_{0.87}$P$_{0.13}$)$_2$ superconductors, it has been reported that the thickness of the electronic nematic domain walls is unexpectedly long, leading to the formation of mesoscopic nematicity wave [T. Shimojima $\textit{et al.}$, Science $\textbf{373}$ (2021) 1122]. This finding demonstrates that the nematic coherence length $\xi_{\rm nem}$ can be decoupled from the lattice domain wall. Here, we report that the electronic domain wall thickness shows a distinct variation in related materials: it is similarly long in FeSe$_{0.9}$S$_{0.1}$ whereas it is much shorter in undoped BaFe$_2$As$_2$. We find a correlation between the thick domain walls and the non-Fermi liquid properties of normal-state resistivity above the nematic transition temperature. This suggests that the nematic coherence length can be enhanced by underlying spin-orbital fluctuations responsible for the anomalous transport properties.