Modulation of Electronic Liquid-Crystal Phases by Local Strain in Few-Layer FeSe Films

Symmetry-broken electronic phases bring abundant correlated phenomena into 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 the 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 the crystalline lattice and electronic liquid-crystal states in FeSe, hence providing a pathway to manipulating the electronic phases at the nanoscale.