STM/S study of surface reconstruction and atomic defects on iron-based superconductors

Surface reconstruction and defects can dramatically modify the properties of iron-based superconductors. Here, we systematically investigated the surface of low-temperature cleaved parent and doped BaFe₂As₂ superconductors by scanning tunneling microscopy/spectroscopy (STM/S). STM imaging reveals the emergency of a new reconstruction while increasing the temperature from 77K to 165K. The structural and electronic properties of this new surface reconstruction was investigated. We have also induced atomic defects on the surface by tip scanning and the electronic property of those tip-induced defects showed similarity with the reconstructed surface.