Role of the perovskite-like lattice in the high-temperature superconductor mechanism: EXAFS data analysis

Abstract

The temperature-dependent extended X-ray absorption fine structure (EXAFS) spectra of hole- and electron-doped high-temperature superconductors (La2 − xSrxCuO4 and Nd2 − xCexCuO4 − δ, respectively) are investigated above the CuK absorption edge. It is demonstrated that, for superconducting compounds (x = 0.15), the part of the oxygen ions in the CuO2 plane oscillates in the double-well potential, and their oscillations are correlated with the charge-carrier transport. The presented data indicate the direct relation between the experimentally observed local dynamic structural inhomogeneity and the local dynamic charge ordering. A phenomenological description of the correlation between the local electronic and local crystalline structures, which enables us to reveal the role of collective oxygen-ion oscillations inherent to the perovskite-like lattice in the establishment of the superconducting state in doped La2CuO4 and Nd2CuO4, is proposed to explain the experimental results.