Paramagnetic Effect in Superconductors. III. Measurements on Hollow Cylinders of Mercury and Tin

Abstract

The circular flux which is set up by a longitudinal current passing through a hollow cylinder has been measured in the intermediate state by ballistic and fluxmetric methods. The flux has a maximum in the transition region and drops to zero in the pure superconducting state, which is in qualitative agreement with theoretical predictions. The dependance of the maximum of the flux increase on the current and on the ratio of the inner to the outer diameter of the sample was found to be different from the the theory. It was found, in particular that the ratio ${\tilde{K}}_{m\varphi }$ of the maximum flux, ${\Phi }_{max}$, to the flux in the normal conducting state ${\Phi }_n$ is not independent of the current. It is not possible to correct the theory from these measurements alone. However, it seems very likely that the correction which has to be applied here is intimately connected with the correction term $1-\frac{I_g}{I}$ which has to be applied to the theory of the paramagnetic effect.