IMPURITY EFFECT ON THE TRANSITION TEMPERATURE OF THE SUPERCONDUCTING FULLERIDES

We study the alkali-metal-doped fulleride systems based on an impurity model. The bound states are induced by the impurity potential, and the local density of states of the neighboring molecules at the Fermi level is remarkably reduced. We point out that the superconductivity of the whole system will be destroyed when the average distance between the impurities reaches the order of the coherence length. It gives a reasonable explanation to the strange behavior of the transition temperature of the superconducting fuller ides.