URANIUM-BASED HEAVY-FERMION SUPERCONDUCTORS - AN EXPERIMENTAL SURVEY

The uranium-based heavy-fermion superconductors were discovered almost one decade ago. Here, we present an experimental survey of their interesting normal and superconducting state properties. It appears that most of the unusual normal-state properties can be attributed to the proximity of an antiferromagnetic instability and the presence of competing electronic interactions. The discovery of a superconducting instability in these strongly-correlated electron systems came totally unexpected. The parameters describing the superconducting state yield strong deviations from the standard BCS behaviour. Accumulating evidence has been gathered for a nontrivial superconducting pair function (L not-equal 0). We illustrate recent developments by a number of prime studies, like high-field measurements and alloying experiments, and give special attention to multicomponent superconductivity in UPt3 and (U, Th)Be13.