  Understanding the interplay of structural and electronic symmetry breaking in
Fe-based high temperature superconductors remains of high interest. In this
work we grow strain-patterned multilayer FeSe thin films in a range of
thicknesses using molecular beam epitaxy. We study the formation of electronic
nematic domains and spatially-varying strain using scanning tunneling
microscopy and spectroscopy. We directly visualize the formation of edge
dislocations that give rise to a two-dimensional edge dislocation network in
the films. Interestingly, we observe a 45 degree in-plane rotation of the
dislocation network as a function of film thickness, yielding antisymmetric
strain along different directions. This results in different coupling ratios
between electronic nematic domains and antisymmetric strain. Lastly, we are
able to distinguish between different orthogonal nematic domains by revealing a
small energy-dependent difference in differential conductance maps between the
two regions. This could be explained by orbital-selective tip-sample tunneling.
Our observations bring new insights into the dislocation network formation in
epitaxial thin films and provide another nanoscale tool to explore electronic
nematicity in Fe-based superconductors.
