Anomalous dispersion of longitudinal optical phonons in Nd1.86Ce0.14CuO4+δ determined by inelastic x-ray scattering -: art. no. 167002

The phonon dispersions of Nd1.86Ce0.14CuO (4+delta) along the [xi, 0, 0] direction have been determined by inelastic x-ray scattering. Compared to the undoped parent compound, the two highest longitudinal phonon branches, associated with the Cu-O bond stretching and out-of-plane oxygen vibration, are shifted to lower energies. Moreover, an anomalous softening of the bond-stretching band is observed at about q=(0.2, 0, 0). These signatures provide evidence for strong electron-phonon coupling in this electron-doped high-temperature superconductor.