Doping dependence of density response and bond-stretching phonons in cuprates

Abstract

We explain the anomalous doping dependence of zone boundary $(π,0)$ and $(π,π)$ bond-stretching phonons in the high-temperature superconductor La$_{2-δ}$Sr$_δ$CuO$_4$ in the doping range $0<δ<0.35$. Our calculations are based on a theory for the density response of doped Mott-Hubbard insulators.