Conducting and superconducting properties of alkali-metal C₆₀ fullerides

Conductivity and superconductivity in alkali-metal C₆₀ fullerides (A_xC₆₀, where A=Li, Na, K, Rb, Cs or their mixtures) are reviewed and discussed in terms of the behaviour of conduction electrons in the systems, focusing in particular on electron paramagnetic resonance (EPR) studies. The influence of the modified intermolecular contacts (staggered C-C pentagon-hexagon fusions in the face-centred cubic structure, C-C hexagon fusions nested over pentagons or hexagons in the primitive cubic structure) on the electronic states of A₃C₆₀ is described. The variation in dimensionality and its effect on the change in electronic properties of A₁C₆₀ are also described. The question of further elevating the superconducting transition temperature is addressed on the basis of the evolution of the spin-lattice relaxation times of conduction electrons.