Symmetry of the 3 d 9 ligand hole induced by doping in Y Ba 2 </mml:…
1988; American Physical Society; Volume: 38; Issue: 10 Linguagem: Inglês
10.1103/physrevb.38.7196
ISSN1095-3795
AutoresA. Bianconi, Marianna De Santis, Andrea Di Cicco, A.‐M. Flank, A. Fontaine, P. Lagarde, Hiroshi Katayama‐Yoshida, A. Kotani, A. Marcelli,
Tópico(s)Magnetic properties of thin films
ResumoPolarized Cu ${L}_{3}$-edge x-ray absorption spectra of a single crystal of Y${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{6.8}$ have been measured to determine the symmetry of the orbital of the electronic holes induced by doping. The states induced by doping in $\mathrm{Y}{\mathrm{Ba}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\ensuremath{-}\ensuremath{\delta}}$ ($0<\ensuremath{\delta}<\ensuremath{\sim}0.5$) have been found to be ligand holes ${\mathit{L}}^{*}$, giving the ${3d}^{9}{\mathit{L}}^{*}$ configuration, and their weight is correlated with ${T}_{c}$. The polarization dependence shows that the hole ${\mathit{L}}^{*}$, induced by doping, is found to be mainly in the Cu-O orbital oriented along the $\mathbf{c}$ axis involving the $\mathrm{O} {2p}_{z}$ orbital of the O(4) atom in the Ba plane and the $\mathrm{Cu} {3d}_{{z}^{2}}$ orbitals. This result indicates the important role of BaO layers and shows that theories of high-${T}_{c}$ superconductivity have to take account of a second band with different symmetry, beyond the single band (the two-dimensional band derived from the $\mathrm{Cu} {3d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ and O ${2p}_{x}$, ${2p}_{y}$ orbitals in the $\mathbf{a}\ensuremath{-}\mathbf{b}$ plane of the Cu${\mathrm{O}}_{2}$ layers) usually considered in models of the electronic structure of high-${T}_{c}$ superconductors.
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