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Origin Of The Electron-Hole Asymmetry In The Scanning Tunneling Spectrum Of The High-Temperature Bi₂Sr₂Cacu₂O₈+Δ Superconductor, Jouko Nieminen, Hsin Lin, R. Markiewicz, A. Bansil
Origin Of The Electron-Hole Asymmetry In The Scanning Tunneling Spectrum Of The High-Temperature Bi₂Sr₂Cacu₂O₈+Δ Superconductor, Jouko Nieminen, Hsin Lin, R. Markiewicz, A. Bansil
Robert Markiewicz
We have developed a material specific theoretical framework for modeling scanning tunneling spectroscopy (STS) of high-temperature superconducting materials in the normal as well as the superconducting state. Results for Bi₂Sr₂CaCu₂O₈₊δ (Bi2212) show clearly that the tunneling process strongly modifies the STS spectrum from the local density of states of the dₓ2₋y2 orbital of Cu. The dominant tunneling channel to the surface Bi involves the dₓ2₋y2 orbitals of the four neighboring Cu atoms. In accord with experimental observations, the computed spectrum displays a remarkable asymmetry between the processes of electron injection and extraction, which arises from contributions of Cu dz2 and …
Angle-Resolved Photoemission-Study Of (100), (110), And (111) Surfaces Of Cu0.9a10.1: Bulk And Surface Electronic-Structure Of The Alloy, H. Asonen, M. Lindroos, M. Pessa, P. Prasad, R. Rao, A. Bansil
Angle-Resolved Photoemission-Study Of (100), (110), And (111) Surfaces Of Cu0.9a10.1: Bulk And Surface Electronic-Structure Of The Alloy, H. Asonen, M. Lindroos, M. Pessa, P. Prasad, R. Rao, A. Bansil
Arun Bansil
We present angle-resolved photoemission spectra from the low-index faces of CuAl single crystals using 16.85- and 21.22-eV radiation, together with the computed bulk electronic structure of the alloy within the framework of the muffin-tin coherent-potential approximation (CPA). The d-band complex of Cu is found to suffer shifts of less than 0.1 eV on alloying, whereas the states of s-p symmetry are lowered in energy by as much as on the order of 1 eV. The dispersion curve of the uppermost valence band is measured and with the extrapolation of this curve to the Fermi energy (EF), the Fermi-surface radii along …