Authors: M.A. Navacerrada and J.V. Acrivos
Affilation: San José State University, United States
Pages: 219 - 222
Keywords: nanofilms, periodic lattice distorsion, synchrotron X-ray diffraction
Synchrotron X-ray diffraction has been used to detect novel periodic lattice distortions (PLD) in highly c-axis oriented YBa2Cu3O7 (YBCO) 50 nm films grown on SrTiO3 substrate. The growth layer by layer of 50 nm YBCO, using high pressure oxygen sputtering system, has been previously proven  .Understanding the structure and distortions of YBCO films grown in this geometry is important for superconducting device fabrication (e.g., SQUIDs, batteries, etc). Several diffractions, at room temperature, at different incident X-ray synchrotron flux show a centre and two sidebands characteristic of PLD. These are usually observed in low dimensional solids undergoing metal to insulator transitions. The observed data can be explained using the established theory for PLD. The relative scattering intensities Shkl versus the scattering vector shkl = 2sin(qhkl)/l of the three peaks are given by ratios of ordinary Bessel function Jn2(x), i. e., S(sb-1):S(c):S(sb1):: J-12(x):J02(x):J12(x) where sb-1 and sb1 are the sidebands about a central diffraction peak c and x is proportional to the projection of q on the given hkl, shkl and the distortion wave amplitude . The distortion vector is q = (0.088, 0.005, 0.02) in the reciprocal lattice (b1, b2, b3) to within ± 0.005.
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