Thermoelectric power of superconducting fullerenes

The temperature dependence of the thermoelectric power S(T) of single crystals of alkali-metal-doped fullerenes is linear from 300 to 100 K, but exhibits a shoulder above the superconducting transition temperature. This behavior is discussed in terms of the electron-phonon interaction. While the possibility of phonon drag is not excluded, it is shown that the low-temperature behavior is consistent with electron-phonon mass-enhancement effects if it is assumed that the electrons are coupled strongly to low-frequency interball or ball--alkali-metal-atom phonons.