Paramagnetic Effect in Superconducting Tin, Indium, and Thallium

Abstract

Measurements have been carried out on the longitudinal magnetization of pure rods in the intermediate state between normal and superconduction. The observed "paramagnetic" flux increase is dependent on the externally sustained current, external magnetic field, and temperature only. The dependence is much the same for the metals studied. There is a threshold current to be exceeded before the flux increase is observed. The threshold is linearly dependent on the external magnetic field; the slope of the threshold curve is the same for the metals studied. The results compare favorably with existing theory, except for the threshold. An upper limit has been placed on the relaxation time for the currents responsible for the flux increase. The effect of the physical purity of the sample has been observed.