Temperature dependent local structure of the CuO2 plane in the 18 doped La1.875Ba0.125CuO4 system

Local structure of the Cu site in the 18 doped insulating La1.875Ba0.125CuO4 system has been studied by Cu K-edge extended x-ray absorption spectra (EXAFS). The correlated Debye-Waller factor of the CuO(planar) pairs shows an anomalous increase below ∼ 70K indicating structural fluctuations in the CuO2 lattice. The results are in agreement with the recent diffraction studies showing 70K as an onset temperature for a superstructure peak due to charge modulation in the system, below the transition from average low temperature orthorhombic (LTO) to average low temperature tetragonal (LTT) structure.