Phonons and superconductivity in Bi2Sr2CaCu2O8

Abstract

Detailed neutron scattering measurements have been made for selected phonons for ${\mathrm{Bi}}_2$ ${\mathrm{Sr}}_2$ ${\mathrm{CaCu}}_2$ ${\mathrm{O}}_8$. The temperature dependence of the linewidths indicates large anharmonic effects particularly for the oxygen modes. The superconductivity induced change in width below ${\mathit{T}}_{\mathit{c}}$ of the two highest energy oxygen modes is found to be nearly 2% of the phonon energy suggesting a large electron phonon coupling.