Heavy fermion superconductors are largely studied for the rich variety of their unconventional ground states. But the discovery of new Pr and Ce based systems which are superconducting at zero pressure, revealed multigap effects with a remarkably low "critical" field scale Hc2 S for the small gap band (of order Hc2/100). We present results on the skutterudite heavy-fermion compound PrOs4Sb 12 (Tc ≈ 1.8K), where both the low field and the low temperature behavior of its thermal conductivity yield evidence for multigap superconductivity as well as new ongoing results on CeCoIn5 (T c ≈ 2.3K). Although the proximity of this last system to a quantum critical point prevents quantitative analysis of the values of the gaps as in PrOs4Sb12, it shows even stronger multigap effects (H c2S ≈ Hc2/1000...), backing the ideas that the multiband behavior is intimately related to the role of the f electrons in the pairing mechanism.
ASJC Scopus subject areas
- Physics and Astronomy(all)