Magnetic Origin of Electronic Nematicity in NaFeAs (Part II)

The characterization of possible broken symmetries is essential to understanding high-temperature superconductivity. The electronic states of many iron-based superconductors have been shown to break rotational symmetry, but the origin of this nematicity remains elusive. We use Scanning Tunneling Microscopy (STM) and Spectroscopy (STS) to directly visualize the spatial structure of electronic states in NaFeAs. Intrinsic defects produce unidirectional spectroscopic features that persist to temperatures well above both the spin density wave (SDW) and orthorombic transitions. By comparing our measurements to angle-resolved photoemission spectroscopy (ARPES) data on the same material, we find that these features arise from quasiparticle interference (QPI) in the presence of magnetic order, indicating the primary role of spin interactions in electronic nematicity.