Abstract
exhibits properties that are characteristic of the parent compounds of the newly discovered iron (Fe)-based high- superconductors. By combining real-space imaging of scanning tunneling microscopy and spectroscopy () with momentum-space quantitative low-energy electron diffraction (LEED), we have identified the surface plane of cleaved crystals as the As terminated Fe-As layer—the plane where superconductivity occurs. LEED and data on the surface indicate an ordered arsenic (As) terminated metallic surface without reconstruction or lattice distortion. It is surprising that STM images the different Fe-As orbitals associated with the orthorhombic structure, but not the As atoms in the surface plane.
- Received 19 May 2009
DOI:https://doi.org/10.1103/PhysRevLett.103.076104
©2009 American Physical Society