We show that the near degeneracy of the low-lying vector (${\mathit{T}}_{1\mathit{u}}$) and axial-vector (${\mathit{T}}_{1\mathit{g}}$) levels in an isolated ${\mathrm{C}}_{60}^{\mathrm{-}}$ can provide a simple pairing mechanism in ${\mathrm{C}}_{60}^{2\mathrm{-}}$, ${\mathrm{C}}_{60}^{3\mathrm{-}}$, and the ${\mathrm{K}}_{\mathit{n}}$${\mathrm{C}}_{60}$ crystal. This gives rise to the possibility of a ‘‘boson’’ band in ${\mathrm{K}}_{\mathit{n}}$${\mathrm{C}}_{60}$, in addition to the usual fermion bands. The implications for superconductivity are discussed.

• Received 23 June 1992

DOI:https://doi.org/10.1103/PhysRevB.46.14150