Title: Cluster-configuration-interaction analysis of Cu 2<i>p</i>and valence-band photoemission measurements on<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Bi</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Sr</mml:mi></mml:mrow><mml:mrow><…
Abstract: The electronic structure of ${\mathrm{Bi}}_{2}$${\mathrm{Sr}}_{2}$${\mathrm{CaCu}}_{2}$${\mathrm{O}}_{8}$ and ${\mathrm{Bi}}_{2}$${\mathrm{Sr}}_{2}$${\mathrm{CuO}}_{6}$ high-${\mathit{T}}_{\mathit{c}}$ superconductors is investigated by Cu 2p x-ray photoemission spectroscopy and valence-band resonant photoemission at the Cu ${\mathit{L}}_{3}$ edge. The data suggest strong correlation effects for the Cu 3d electron states due to a large on-site Coulomb interaction. By means of a simplified cluster-configuration-interaction model we derive the model Hamiltonian parameters which quantify the Cu d-d interaction energy, the O to Cu charge-transfer energy, and the degree of Cu d--O 2p hybridization. The solutions for the two compounds differ mainly in the charge-transfer energy, which in both cases is lower than the energy required for a Cu d-d charge fluctuation. An energy gap of about 1 eV for both compounds is found. This identifies them as charge-transfer insulators, in analogy with what was already found for CuO and other copper oxide based high-${\mathit{T}}_{\mathit{c}}$ superconductors. The density of states at the Fermi level is assigned to doping induced states in the semiconductor gap.
Publication Year: 1995
Publication Date: 1995-01-01
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
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Cited By Count: 4
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