Raman study of the electron–phonon interaction in light alkali metal intercalated metallicfullerides

Abstract

By laser-irradiating polymeric Li4C60 and Na4C60, we have obtained pure monomeric metallic phases stable at ambient conditions.Based on a systemic Raman analysis, we have determined the electron–phononcoupling constant for both metallic phases. The e–p coupling constants of Li- andNa-intercalated metallic fullerides are smaller than those of superconductiveK3C60 andRb3C60 and comparable to or slightly higher than that of ambient-pressure non-superconductiveCs3C60. We predict that Na-doped fulleride could exhibit superconductivity withTc ∼ 10 K. Muchlower Tc or even no superconductivity can be expected for the Li-doped fulleride which exhibits a strongLi + –C interaction. These results contribute to the understanding of superconductivity in lightalkali metal intercalated fullerides.