STRIPE STRUCTURE OF THE CUO2 PLANE IN BI2SR2CACU2O8-RAY-DIFFRACTION(YBY ANOMALOUS X)

The modulated structure of the CuO2 plane in Bi2Sr2CaCu2O8+y supercond uctor has been solved by Cu K-edge anomalous x-ray diffraction. The di splacement of Cu ions along the c axis shows the largest amplitude and anharmonic character. The results show flat stripes of CuO2 lattice o f width L = 15.5 Angstrom with long Gu-Bi distances that are separated by stripes of bent CuO2 plane and shorter Cu-Bi distances. In each Cu O2 bilayer the flat stripes in a first layer are close to the bent str ipes in the second layer, suppressing the electronic coupling between the two adjacent planes.