THE DIFFICULTY IN IDENTIFYING EXOTIC SUPERCONDUCTORS

Conventional s-wave superconductors have order parameters with no inte rnal degrees of freedom - they are characterized by an amplitude and a phase. All unconventional superconductors share the property of a non trivial internal symmetry which makes their behavior more interesting and their identification more difficult. The determination of the orde r parameter of the longest-studied exotic superconductor, superfluid H e-3, remains inconclusive despite the existence of a Standard Model. U sing superfluid He-3 as a cautionary tale, the experimental evidence f or the identification of order parameters of other exotic superconduct ors is also examined.