Surface Pinning Phenomena in Superconducting Chevrel-Phase PbMo6S8

Abstract
Surface pinning was investigated by using an ac measuring method for superconducting PbMo6S8 tapes and wire prepared by electroplating and diffusion methods. A strong surface pinning was observed only for specimens with shorter heating-up times. The highest obtained value of the surface critical current density was 1.40×1010 Am-2 at B=5 T, which is comparable to the bulk critical current density of Nb3Sn. Such a strong pinning seems to be mainly caused by fine grains in the surface region.