Optical Spectra in the Ferromagnetic States near the Charge Ordering

The optical conductivity is studied numerically for the ferromagnetic metallic state close to the charge ordering observed in perovskite manganites. We focus on roles of the charge fluctuation on the incoherent component in the optical spectra, and consider the Coulomb interaction in the one- and two-dimensional spinless fermion models. The numerical results show that the incoherent part is not noticeable, and near the quarter-filling, most of the spectral weights are transferred to the Drude component. The discrepancy between our calculations and the experiments suggests that the orbital degrees of freedom play important roles.