Planar oxygen-centered lattice instabilities in Tl-based high- temperature superconductors

• Published in: Physica. C, Superconductivity Superconductivity, 1994-02, Vol.220 (3), p.377-382
• Main Authors: de Leon, J.Mustre, Li, G.G., Conradson, S.D., Bishop, A.R., Subramanian, M.A., Raistrick, I.D.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cuprates superconductors (high tc and insulating parent compounds); Exact sciences and technology; High-Tc compounds; Inorganic compounds; Physics; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Superconductivity; Water, oxides, hydroxides, peroxides; X-ray absorption spectroscopy: exafs, nexafs, xanes, etc; X-ray diffraction and scattering; Y-based cuprates
• ISSN: 0921-4534; 1873-2143
• DOI: 10.1016/0921-4534(94)90927-X

Analysis of the copper K-edge X-ray absorption finestructure on Tl 2Ba 2CuO 6, Tl 2Ba 2CaCu 2O 8, and Tl 2Ba 1.2Sr 0.8 CuO 6 indicates that the copper-equatorial oxygen local structure changes in the vicinity of the superconducting transition. These data also show that the radial distribution function for these bonds is complex with several oxygen positions relative to the copper, indicating that the local structure of the CuO 2 planes differs significantly from the average crystal structure. These results suggest the presence of polarons in these planes, whose structure changes across the superconducting transition, and are thus coupled to the hole pairing states.