Transition from Type-I to Type-II Superconducting Behaviour with Temperature observed by $μ$SR and SANS

Aegerter, C. M.; Keller, H.; Lee, S. L.; Ager, C.; Ogrin, F. Y.; Cubitt, R.; Forgan, E. M.; Nutall, W. J.; Kealey, P. G.; Lloyd, S. H.; Johnson, S. T.; Riseman, T. M.; Nutley, M. P.

Transition from Type-I to Type-II Superconducting Behaviour with Temperature observed by $μ$SR and SANS

Authors

Description

We investigate the superconducting behaviour of Bi doped Pb. Pure lead shows type-I behaviour entering an intermediate state in a magnetic field. High dopings of Bi ($>$3%) lead to type-II behaviour showing a mixed state, where the magnetic field penetrates the superconductor in the form of a flux lattice. At intermediate doping, the sample shows both type-I and type-II behaviour depending on the temperature. This arises because the Ginzburg-Landau parameter $κ$ passes through its critical value of $1/\sqrt{2}$ with temperature.
8 pages, 7 figures