Physical Properties of Metal-Doped Fullerene Superconductors

This chapter discusses the physical properties of metal-doped fullerene superconductors. The key component of the fullerene superconductors is the molecular cluster C60, or Buckminsterfullerene. The chapter provides an overview of the experimental status of the fullerene superconductors emphasizing on (1) the normal state and superconducting state phenomenology and (2) experimental probes of the microscopic mechanism of superconductivity in two new molecular superconductors (K3C60 and Rb3C60). The chapter also presents a few models to explain fullerene superconductivity. Theoretical models put forth to explain superconductivity in the fullerenes range from the conventional electron-phonon-mediated pairing model of Bardeen, Copper, and Schreiffer (BCS) to models in which pairing is mediated by electron correlation effects. Finally, within the context of these models, the chapter provides an overview of (1) the dependence of critical transition temperatures on lattice constant of C60, (2) the energy gap, (3) phonons, and (4) the isotope effect.