Phonon raman linewidth in correlated metals

Abstract

We calculate the phonon linewidth of a Raman-active zone centre phonon in a correlated metal. The correlated metal is described by the half-filled single-band Hubbard model on a hypercubic lattice in d=∞ . The electronic self-energy and Green function are determined within the dynamical mean field theory (DMFT) for various values of U in the metallic regime and then used to calculate the phonon linewidth. We consider only the lowest order contribution corresponding to a process in which the phonon decays into a particle-hole pair. At weak correlation we find that the electronic contribution to the phonon linewidth is negligibly small but it grows with increasing correlation strength and then reaches a maximum before showing a decrease.