Relaxation Effects Connected with the Transition Between the Superconducting and Normal States

Several authors have suggested that the relaxation effects frequently observed in experiments on the magnetic properties associated with superconductivity may be due to the slow decay, caused by a very small resistance, of eddy currents in the specimen. Similar relaxation effects have recently been observed by the authors and Wilhelm in experiments on persistent currents in a closed superconducting circuit. Viewed in the light of a marked parallelism in behavior of all time effects, these experiments definitely confirm the above suggestion. Further, a simple thermodynamic argument shows that the same cause will produce relaxation in the thermal equilibrium, and so will account also for the time effects in the calorimeter experiments of Keesom and van Laer.