Raman study of the electron-phonon interaction in light alkali metal intercalated metallic fullerides

摘要

By laser-irradiating polymeric Li_4C_(60) and Na _4C_(60), we have obtained pure monomeric metallic phases stable at ambient conditions. Based on a systemic Raman analysis, we have determined the electron-phonon coupling constant for both metallic phases. The e-p coupling constants of Li-and Na-intercalated metallic fullerides are smaller than those of superconductive K_3C_(60) and Rb _3C_(60) and comparable to or slightly higher than that of ambient-pressure non-superconductive Cs_3C_(60). We predict that Na-doped fulleride could exhibit superconductivity with T_c ～ 10K. Much lower T_c or even no superconductivity can be expected for the Li-doped fulleride which exhibits a strong Li~+-C interaction. These results contribute to the understanding of superconductivity in light alkali metal intercalated fullerides.