Biao Hu

Surface Geometric and Electronic Structures of BaFe2As2(001)

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.

Structure-property coupling in Sr3(Ru1−xMnx)2O7

Layered ruthenates are prototype materials with strong structure-property correlations. We report the structural and physical properties of double-layered perovskite Sr3(Ru1−xMnx)2O7 single crystals with 0≤x≤0.7. Single crystal x-ray diffraction refinements reveal that Mn doping on the Ru site leads to the shrinkage of unit-cell volume and disappearance of (Ru/Mn)O6 octahedron rotation when x>0.16, while the crystal structure remains tetragonal. Correspondingly, the electronic and magnetic properties change with x. The electrical resistivity reveals metallic character (dρ/dT>0) at high temperatures but insulating behavior (dρ/dT<0) below a characteristic temperature TMIT. Interestingly, TMIT is different from TM, at which magnetic susceptibility reaches maximum. TMIT monotonically increases with increasing x while TM shows non-monotonic dependence with x. The difference between TMIT and TM (TMIT>TM) becomes larger when x>0.16. The constructed phase diagram consists of five distinct regions, demonstrating that the physical properties of such a system can easily be tuned by chemical doping.

Surface and bulk structural properties of single-crystalline Sr3Ru2O7

We report temperature and thermal-cycling dependence of surface and bulk structures of double-layered perovskite

Atomic-Scale Fingerprint of Mn Dopant at the Surface of Sr3(Ru1-xMnx)2O7

{\text{Sr}}_{3}{\text{Ru}}_{2}{\text{O}}_{7}

Hidden phases revealed at the surface of double-layeredSr3(Ru1−xMnx)2O7

single crystals. The surface and bulk structures were investigated using low-energy electron diffraction (LEED) and single-crystal x-ray diffraction (XRD) techniques, respectively. Single-crystal XRD data is in good agreement with previous reports for the bulk structure with

Doping and dimensionality effects on the core-level spectra of layered ruthenates

{\text{RuO}}_{6}

Manganese-induced magnetic symmetry breaking and its correlation with the metal-insulator transition in bilayered Sr3(Ru1-xMnx)2O7

octahedral rotation, which increases with decreasing temperature [

Single-bilayerE-type antiferromagnetism in Mn-substituted Sr3Ru2O7: Neutron scattering study

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Unveiling the Atomic and Electronic Structure at the Surface of the Parent Pnictide SrFe2As2

at 300 K and

STM study of the Mn-dopants on the surface of Sr

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