Symmetric (002) reflections for (a) LSCO on STO, (b) LSCO on LAO. The sharp, intense peaks are diffractions from the substrates and the less intense peaks are diffractions from the films. Note the large difference in lattice constant between the two films.
k2χ(k) EXAFS for the LSCO films grown on STO and LAO substrates. The film geometry relative to the polarization vector of the synchrotron beam is indicated. The data have been offset for clarity. They have been stacked vertically in order of ascending first-neighbor Co–O bond length.
(Color online) Perovskite structure for LSCO films. Shown are the strain-dependent, local structural coordinates.
(Color online) Fourier transforms of the EXAFS data shown in Fig. 2 and best fit using ifeffit. The fit included single scattering Co–O, Co–La, Co–Sr, Co–Co, and Co–O paths as well as collinear double and triple multiple-scattering paths involving third-neighbor Co and first-neighbor O atoms. Note the similarity between the amplitude of the first shell and the line shape of the higher shells for transforms recorded along the tensile [(a) and (d)] and compressive [(b) and (c)] strain directions. These features are well modeled by the fit.
Results of EXAFS modeling for the in- and out-of-plane Co–O bond lengths and Co–La, Co–Sr, Co–Co, and Co–O higher-shell distances. The EXAFS results are compared to the structural parameters derived from the model in Fig. 3 and the XRD determination of the in- and out-of-plane lattice constants. Also shown are the relative distortions between them.
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