Study of Cu--O and Cu--La Pair Correlations in Superconducting La₂CuO_4.1 System by Cu K-Edge EXAFS

抄録

We report Cu K-edge extended X-ray absorption fine structure (EXAFS) spectra up to high momentum transfer measured on a superconducting La₂CuO_4.1 single crystal using in-plane polarization of synchrotron light. The EXAFS data with a high signal to noise ratio has enabled the precise determination of the Debye-Waller factors and the pair correlations of Cu--O (planar) and Cu--La pairs of the structurally complex superconducting system. We have observed an anomalous behaviour of the pair correlations at -- 170, K and attributed it to an interplay between temperature-dependent structural modulation of the perovskite and rock-salt layers in the title compound.