Theory and Experiments on Periodic Lattice Distortions that Explain 1D Conductivity along the CuO2 Plane Ab And A-B Diagonals in YBa2Cu3O7 (YBCO) 50 nm Film with a 24 DEG Grain Boundary (Gb)
H.S. Sahibudeen, M.A. Navacerrada and J.V. Acrivos
San Jose State University, US
cuprates, SCF calculations, superconductivity, XRD, PLD
Self consistent field (SCF) calculations carried out at San José State University (using MOLECOLE Linux codes) for a nano-particle of 18 molecules of T’-Nd2CuO4 explain the dxy symmetry for preferred superconductivity in the ab plane. These indicate that 1D conductivity is induced along the ab diagonal when there is a periodic lattice distortion (PLD) at site R: uexp(i(2pR.q+f)) (measured in X-ray diffraction (XRD)) of wave vector q and amplitude u. XRD and X-ray absorption (XAS) measurements were done (at the Stanford Synchrotron Radiation Laboratory (SSRL) and at the Lawrence Berkeley National Laboratory (LBNL-ALS)) on 50 nm c-axis oriented YBCO films (deposited on single crystal SrTiO3 and bi-crystals with a 24DEG grain boundary (GB) at the Complutense University). Understanding structure and distortions of YBCO films is important for device fabrication.
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Nanotech 2005 Conference Program Abstract