Revelations of the fullerenes

Abstract

The discovery that the face-centred cubic form of the fullerene Cs3C60 is a superconductor, just as its body-centred cubic counterpart is, sheds light on the origin of superconductivity in organic materials. Superconductivity and magnetic order are well known in C60 compounds of the form A3C60 (where A is an alkali metal). The spherical C60 molecular ions in these superconducting crystals are almost exclusively arranged in a face-centred cubic lattice; the one exception is Cs3C60, where the known superconducting phase has a body-centred cubic packing. Now Ganin et al. have isolated the face-centred cubic polymorph of Cs3C60, and show that it too is superconducting, although its magnetic properties are very different from its body-centred cubic counterpart. The identification of these two distinct superconducting crystal structures in the same material should help to elucidate the nature of the subtle interplay between structure, magnetism and superconductivity in this and other high-temperature superconducting systems.