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Science 19 February 1988:
Vol. 239. no. 4842, pp. 896 - 899
DOI: 10.1126/science.239.4842.896
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Articles

Electronic Structure and Valence-Bond Band Structure of Cuprate Superconducting Materials

YUEJIN GUO 1, JEAN-MARC LANGLOIS 1, and WILLIAM A. GODDARD III 1

1 Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125.

From ab initio calculations on various clusters representing the La2-xSrxCu1O4 and Y1Ba2Cu3O7 classes of high-temperature superconductors, it is shown that (i) all copper sites have a CuII(d9)oxidation state with one unpaired spin that is coupled antiferromagnetically to the spins of adjacent CuII sites; (ii) oxidation beyond the cupric (CuII) state leads not to CuIII but rather to oxidized oxygen atoms, with an oxygen ppgr hole bridging two CuII sites; (iii) the oxygen ppgrhole at these oxidized sites is ferromagnetically coupled to the adjacent CuIId electrons despite the fact that this is opposed by the direct dd exchange; and (iv) the hopping of these oxygen ppgr holes (in CuO sheets or chains) from site to site is responsible for the conductivity in these systems (N-electron band structures are reported for the migration of these localized charges).

Submitted on December 7, 1987
Accepted on January 20, 1988


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Antiferromagnetic Exchange Energies in Planar Cuprates.
K. B. LYONS and P. A. FLEURY (1989)
Science 245, 767
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Chemistry of High-Temperature Superconductors.
A. W. Sleight (1988)
Science 242, 1519-1527
   Abstract »    PDF »
A Testable Theory of Superconductivity: New calculations from a theory based on magnetic interactions predict superconductors will never reach room temperature.
R. Pool (1988)
Science 242, 31
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The Magnon Pairing Mechanism of Superconductivity in Cuprate Ceramics.
G. CHEN and W. A. GODDARD III (1988)
Science 239, 899-902
   Abstract »    PDF »


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