J. Phys. IV France 7 (1997) C2-167-C2-168
Determination of Local Atomic Structure by 2p X-Ray Absorption Spectra of Rare-Earth Elements in T- and T'-Phase MaterialsZ.Y. Wu1, 2 and M. Benfatto2
1 Institut des Matériaux de Nantes, UMR 110 du CNRS, Laboratoire de Chimie des Solides, 2 rue de la Houssinière, 44072 Nantes cedex 03, France
2 INFN, Laboratori Nazionali di Frascati, P.O. Box 13, 00044 Frascati, Italy
We have found a genaral rule that links the presence of a particular feature at about 20 eV from the rising edge in the X-ray absorption near edge structure (XANES) spectra at the La, Nd, Gd, Y, and Sr L3-edge in T- and T'-phase materials with the geometrical arrangement around the absorbing site. The absorption spectra of La2-xSrxCuO4, Nd2CuO4, Gd2CuO4, and YBa2Cu3O7 compounds are analysed by full multiple-scattering theory with complex potential of Hedin-Lundqvist type obtaining very good agreement between theory and experiments. As a result of this analysis we show that this feature appears everytime the photoabsorber has an eightfold hexahedron-type coordination with its nearest neighbors. This finding can be used to determine the rare-earth ordering in T*-phase superconductors.
© EDP Sciences 1997