Softening of Cu-O bond stretching phonons in tetragonal HgBa2CuO4+δ -: art. no. 197005

Phonons in nearly optimally doped HgBa2CuO4+delta were studied by inelastic x-ray scattering. The dispersion of the low-energy modes is well described by a shell model, while the Cu-O bond stretching mode at high energy shows strong softening towards the zone boundary, which deviates strongly from the model. This seems to be common in the hole-doped high-T-c superconducting cuprates, and, based on this work, not related to a lattice distortion specific to each material.