RADIATIVE DEFECTS STRUCTURE IN HTSC THIN-FILMS - POLARIZED XAS STUDY

Copper K-edge polarized EXAFS and XANES data of YBa2Cu3O6.9 and Nd1.85Ce0.15CuO4 films indicate that He+ ion irradiation induces the radiative defects that are situated in the chains: (Cu-O-Nd(Ce) for Nd1.85Ce0.15CuO4 and Cu(1)-O(1), Cu(1)-O(4)-Cu(2) for YBa2Cu3O6.9), rather than in the CuO2 (2D) plane. Static disorder with the typical displacement from primary plane site up to 0.1 Angstrom for the O(2) environments was observed for Nd1.85Ce0.15CuO4. In addition the oxygen deficiency in O(1) sites and the disorder of apical O(4) sites were obtained for YBa2Cu3O7-x. At the same time we have not found any local changes in-plane structure after irradiation for both compounds. The data obtained point out the essential role of the ordering in the chains for 2D plane coupling both for hole-type and electron-type high temperature superconductors.