Conventional mechanisms for exotic superconductivity

We consider the pairing state due to the usual BCS mechanism in substances of cubic and hexagonal symmetry where the Fermi surface forms pockets aroun d several points of high symmetry. We find that the symmetry imposed on the multiple pocket positions could give rise to a multidimensional nontrivial superconducting order parameter. The time-reversal symmetry in the pairing state is broken. We suggest several candidate substances where such orderi ng may appear, and discuss means by which such a phase may be identified. [ S0163-1829(99)00942-X].