Nascimento V B, Li Ang, Jayasundara Dilushan R, Xuan Yi, O'Neal Jared, Pan Shuheng, Chien T Y, Hu Biao, He X B, Li Guorong, Sefat A S, McGuire M A, Sales B C, Mandrus D, Pan M H, Zhang Jiandi, Jin R, Plummer E W
Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803-4001, USA.
Phys Rev Lett. 2009 Aug 14;103(7):076104. doi: 10.1103/PhysRevLett.103.076104.
BaFe2As2 exhibits properties that are characteristic of the parent compounds of the newly discovered iron (Fe)-based high-T(C) superconductors. By combining real-space imaging of scanning tunneling microscopy and spectroscopy (STM+STS) with momentum-space quantitative low-energy electron diffraction (LEED), we have identified the surface plane of cleaved BaFe2As2 crystals as the As terminated Fe-As layer-the plane where superconductivity occurs. LEED and STM+STS data on the BaFe2As2(001) 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.
BaFe2As2展现出了新发现的铁基高温超导体母体化合物的特性。通过将扫描隧道显微镜和能谱（STM+STS）的实空间成像与动量空间定量低能电子衍射（LEED）相结合，我们已确定解理后的BaFe2As2晶体的表面平面为砷（As）终止的Fe-As层——即发生超导的平面。BaFe2As2(001)表面的LEED和STM+STS数据表明，这是一个有序的砷终止的金属表面，没有重构或晶格畸变。令人惊讶的是，STM成像出了与正交结构相关的不同Fe-As轨道，但未成像出表面平面中的As原子。
