Investigation of the paramagnetic Meissner effect on Nb disks

The superconducting transition region in a Nb disk showing the paramagnetic Meissner effect (PME) has been investigated in detail. From the field-cool ed magnetization behavior, two well-defined temperatures can be associated with the appearance (disappearance) of the PME: T-1 indicates the character istic temperature where the paramagnetic moment first appears (vanishes) an d a lower temperature T-p defines the temperature where the positive moment no longer increases (begins to decrease). This indicates that the nature o f the PME is reversible and not associated with flux motion. (C) 2000 Elsev ier Science B.V. All rights reserved.