The local structure of the CuO2 plane in Nd2-xCexCuO4-δ: an X- absorption study

The local structure of the CuO2 plane in Nd2-xCexCuO4δ (x=0,0.15;δ∼0.01) has been examined by Cu K-edge EXAFS vs temperature. Three different Cu-O distances can be extracted up to at least 100K, indicating that the atomic structure of the CuO2 plane deviates from the T' structure much more than it was expected earlier. Furthermore, the magnitudes of O1 displacements are larger in a superconducting x=0.15 sample than in a nonsuperconducting x=0 one. Space location of displaced O1 atoms for superconducting sample were obtained from the comparative analyses of experimental and calculated XANES spectra. (au)