STUDY OF CU-O AND CU-LA PAIR CORRELATIONS IN SUPERCONDUCTING LA2CUO4.1 SYSTEM BY CU K-EDGE EXAFS

We report Cu K-edge extended X-ray absorption fine structure (EXAFS) s pectra up to high momentum transfer measured on a superconducting La2C uO4.1 single crystal using in-plane polarization of synchrotron light. The EXAFS data with a high signal to noise ratio has enabled the prec ise determination of the Debye-Waller factors and the pair correlation s of Cu-O (planar) and Cu-La pairs of the structurally complex superco nducting system. We have observed an anomalous behaviour of the pair c orrelations at similar to 170 K and attributed it to an interplay betw een temperature-dependent structural modulation of the perovskite and rock-salt layers in the title compound.