Bound-state formation on a spherical shell: A model for superconductivity of alkali-metal-doped C60

We show that an attractive interaction between two electrons confined to the surface of a sphere gives rise to a bound state, no matter how weak the interaction is. We explore the similarity between a sphere and a (two-dimensional) plane as far as pairing properties are concerned. We also discuss the relevance of the model to a recently discovered superconductor, alkali-metal-doped C60. © 1992 The American Physical Society.