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The axial oxygen atom and superconductivity in YBa sub 2 Cu sub 3 O sub 7

Journal Article · · Science (Washington, D.C.); (USA)

Changes in the copper K-edge x-ray absorption spectrum of YBa{sub 2}Cu{sub 3}O{sub 7} across the critical temperature indicate that, accompanying the superconducting transition, the mean square relative displacement of some fraction of the Cu2-O4 bonds becomes smaller or more harmonic (or both), that there may be a slight increase in the associated Cu1-O4 distance, and that electronic states involving these atom pairs become more atomic-like. If there is an association between the superconductivity and this lattice instability, then the bridging axial oxygen is of central importance in determining the high transition temperature of YBa{sub 2}Cu{sub 3}O{sub 7}. Because this structural perturbation will affect the dynamic polarizability of the copper oxygen sublattice, it is consistent with an excitonic pairing mechanism in these materials. 36 refs., 4 figs.

DOE Contract Number:
AC03-82ER13000
OSTI ID:
6973068
Journal Information:
Science (Washington, D.C.); (USA), Journal Name: Science (Washington, D.C.); (USA) Vol. 243:4896; ISSN SCIEA; ISSN 0036-8075
Country of Publication:
United States
Language:
English