  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.
