Charge Fluctuation in A₃C₆₀ (A=K and Rb): Competition Between Electron-Electron and Electron-Phonon Interactions

抄録

We show that charge fluctuation occurs in A₃C₆₀ due to the competition between electron-electron and electron-phonon interactions and consequently the material remains metallic although both interactions are considerably strong. We calculate the spectral density for A₃C₆₀ based on the dynamical mean-field theory by using the exact diagonalization method. We find a satellite, which is a direct consequence of the charge fluctuation, at about 1.3 eV below the Fermi level. We point out that high-resolution photoemission experiments have shown the existence of this satellite.