Meissner Effect in Au of Au Clad Nb Wire

Abstract

The Meissner effect of Au clad Nb wire has been measured using an ac Hartshorn bridge and a SQUID detector down to 15 mK. The thickness ρ of the Meissner region in Au induced by the proximity effect of Nb becomes larger as the temperature is decreased and almost the whole of the Au sheath shows the Meissner effect at lower temperatures. This effect is drastically suppressed by annealing the sample at about 600°C for a few minutes. The magnetic field dependence of ρ is also investigated. ρ is very sensitive to the magnetic field especially for the annealed sample.