Electronic Properties of Metal Doped Fullerides

Metal doped C60 compounds comprise a class of materials, which includes insulators, conductors and superconductors which exhibit record superconducting transition temperatures Tc for a molecularly based solid. The moderately high values of Tc originate from the interaction of the conduction electrons with high frequency intramolecular phonons, and from the high density of states at the Fermi level. The high density of states and narrow band width arise from the small orbital overlap between the C60 molecules. Hence, both electron-phonon and electron-electron interactions are expected to be important features of the electronic structure of metal doped fullerides. Whereas superconductivity is mediated by electron-phonon interactions in the A3C60 phases, we show that electron-electron interactions determine the low temperature transport properties. We compare the electronic properties of these materials with other classes of superconductors.