Measurements on the Temperature, Current, Magnetic Field Phase Diagram of Superconductivity

Experiments have been carried out to investigate the existence of a paramagnetic effect, reported by other workers, at the transition to superconductivity. While, in the other experiments, the induction in the sample was measured during changes of the magnetic field, the work described in the present paper deals with induction measurements at constant values of magnetic field, current, and temperature. The transition region of tin was investigated by separately varying, stepwise, each of these three parameters. With the current of 10 amperes used in our experiments, no paramagnetic effect was observed anywhere in the transition region.