Optical conductivity in normal-state fullerene superconductors

Abstract

We calculate the optical conductivity sigma(omega) in the normal-state fullerene superconductors by self-consistently including the impurity scatterings, the electron-phonon, and electron-electron Coulomb interactions. The finite bandwidth of the fullerenes and the vertex corrections are explicitly considered in calculating the renormalized Green's function, sigma(omega) is obtained by calculating the current-current correlation function with the renormalized Green's function in the Matsubara frequency and then performing analytic continuation to the real frequency at finite temperature. The Drude weight in sigma(omega) is strongly suppressed due to the interactions and transfered to the mid-infrared region around and above 0.06 eV, which is somewhat less pronounced and much broader compared with the experimental observation by DeGiorgi et al.