碱金属掺杂富勒烯超导体的临界温度和约化能隙研究

碱金属掺杂富勒烯与传统的超导体情况不同，它有一个很宽区域的声子谱，其最高频率和最低频率分别与费密能Ｅ_F和零温超导能隙△₀为同一数量级，这必将导致对原来强耦合超导电性理论的修正。本文在此情况下求解Ｅｌｉａｓｈｂｅｒｇ方程，得到Ｔ_c和△₀的表达式。结果表明，分子间的低频振动模和分子上的高频振动模同样参与电声耦合，Ｔ_c主要取决于声子谱中高频成份的贡献，而△₀的增加主要取决于声子谱中 关键词：

THEORY OF SUPERCONDUCTIVITY IN ALKALI-METAL-DOPED FULLERENES

It is different from the case of conventional superconductors that the alkali-metal-doped fullerenes have wide-frequency-range phonon spectra whose high-and low-frequency phonon modes are, respectively, comparable to the Fermi energy E_F and the zero-temperature gap △₀. This property will lead to a modification to the theory of conventional strong coupling superconductivity. In this paper, by solving the Eliash-berg equations, the expressions of T_c and △₀ are obtained. The results show that both the intermolecular low-frequency modes and the intramolecular highfrequency modes participate the electron-phonon interactions; T_c mainly arise from the high-frequency modes while △₀'s enhancement mainly arise from the low-frequency modes. So, the experimental results can be explained, especially, the large ratio of ２△₀／ｋ_BＴ_c.