No abstract

No abstract

A sharp transition from reversible behaviour to irreversible behaviour in the superconducting mixed slate of single-crystal samples of CeRuz is described. Magnetization, AC susceptibility, resistivity and specific heal measuremenLs under an applied field are reported. The results are discussed in relation to conventional models and those of more novel superconductivity. such as the Fulde-Ferrel stake.

Dilatometric and magnetic experiments on high-quality single crystals of the superconducting compounds UPd2Al3 and CeRu2, which have enhanced spin susceptibilities, demonstrate a first-order transition between weak and strong pinning at T < 0.9T(c) (H > 10 kOe). This is compatible with a staggered order parameter due to the formation of a ''Fulde-Ferrell-Larkin-Ovchinnikov'' state

Recently Siegrist et al. proposed a structure for a high-T, superconductor * * * We would like to thank colleagues who made preprints, referenced here, available to us before publication.