The Superfluidity and Experimental Properties of Odd-Energy-Gap Superconductors

We consider superconductors with a gap which is an odd function of energy k = ek - μ, i.e. vanishing everywhere on the Fermi surface; this is done within a BCS framework. Apart from the standard phenomenology (density of states, penetration depth, NMR, Cv (T)), we also look at the stability of the superconducting state. It is stable to finite supercurrents (although with a normal fluid density which increases with the supercurrent density), and a low concentration of non-magnetic impurities affects the low-temperature transport properties very weakly. We find two classes of odd-gap superconductors, which strongly differ in their low-energy properties. For a certain parameter range, most of the results resemble those for d-wave superconductors (except for the effect of impurities).