X-Ray Absorption Spectra of High T_c Superconducting Sr_xLa_2-xCuO_4-y

Abstract

Cu K-edge extended X-ray absorption fine structure (EXAFS) and near-edge structure have been measured in high T c superconducting Sr x La 2- x CuO 4- y . The Fourir transform analysis shows the axial elongation of CuO 6 octahedron along the c-axis with four short (1.89 Å) and two long (2.41 Å) Cu-O bonds, which are slightly shorter than those in CuO and La 2 CuO 4 indicating the presence of enhanced Cu(3d)-O(2p) interaction. The near-edge spectrum of Sr x La 2- x CuO 4- y is similar to that of Cu 2 O rather than CuO, which is interpreted as an evidence for the monovalent character of Cu ions.