Hysteresis in Superconductors. I. Flux Trapping in Low- and High-κMaterials

Flux-trapping properties of type-II superconductors are described. A linear relationship between the remnant magnetization and the internal field is observed in the low-$\kappa$ superconductors but not in ${\mathrm{Nb}}_3$Sn and ${\mathrm{Nb}}_3$Zr. It was found that the linear relationship and the associated slopes are to a large extent independent of much of the bulk and are related to surface currents. In addition, the linear relationships are observed only in low-$\kappa$ superconductors that exhibit appreciable diamagnetic behavior.