Evidence for critical lattice fluctuations in the high Tc cuprates

Here we provide a direct experimental evidence for critical local lattice fluctuations in the high T(c) superconductors. Cu K-edge extended X-ray absorption fine structure (EXAFS) has been used to measure the distribution of Cu-O bond lengths and the amplitude of local lattice distortions in different materials with increasing chemical pressure on the CuO(2) layers. The stripe formation temperature T(infinity). is determined by the upturn of the Debye Waller factor due to the onset of local lattice distortions. A decrease of the amplitude of lattice fluctuations at the superconducting transition reveals their role in the pairing mechanism. The dynamical lattice fluctuations in the normal phase for T > T(infinity). show diverging lattice fluctuations at the critical chen-deal pressure epsilon (c).