In-plane copper-oxygen bond-stretching mode anomaly in underdoped La2−xSrxCuO4+delta measured with high-resolution inelastic x-ray scattering

International audience; We have measured the lattice dynamics of underdoped La2-xSrxCuO4+ x=0.08 using high resolution inelastic x-ray scattering spectroscopy. The very good intrinsic Q resolution of this experiment allows us to differentiate between the two proposed scenarios for the Cu-O bond stretching phonon broadening reported at q=0.25,0,0. The results suggest that this phonon broadening is due to intrinsic damping rather than to a steep dispersion, having important implications on the interpretation of phonon anomalies in cuprates.