Modulation of electronic liquid crystal phases by local strain in few-layer FeSe films

Symmetry-broken electronic phases bring abundant correlated phenomena in iron-based superconductors. The interplay between subtle lattice distortion and electronic states has drawn sustained interest, yet the underlying microscopic behaviors remain elusive. In this work, we perform a comprehensive scanning tunneling microscopy/spectroscopy study into the lattice structure and electronic smecticity in few-layer FeSe thin films on SrTiO ₃ (001) substrates. By quantitatively extracting the strain tensor components, we visualize the local strain induced by native line defects, including dislocation lines and step-flow edges. Extensive analysis reveals a close dependence of smectic ordering on structural anisotropy. The smectic stripes preferentially align parallel to the shorter Fe-Fe axis of the distorted orthorhombic lattice, and the line defects help to stabilize larger domain blocks. Our findings unveil a unified picture of the coupling between crystalline lattice and electronic liquid crystal states in FeSe, hence provide a pathway to manipulating the electronic phases at the nanoscale.