Dispersion of the high-energy phonon modes in Nd1.85Ce0.15CuO4 -: art. no. 184517

The dispersion of the high-energy phonon modes in the electron-doped high-temperature superconductor Nd1.85Ce0.15CuO4 has been studied by inelastic neutron scattering. The frequencies of phonon modes with Cu-O bond-stretching character drop abruptly when going from the Brillouin zone center along the [100] direction; this dispersion is qualitatively similar to observations in the hole-doped cuprates. We also find a softening of the bond-stretching modes along the [110] direction but which is weaker and exhibits a sinusoidal dispersion. The phonon anomalies are discussed in comparison to hole-doped cuprate superconductors and other metallic perovskites.