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-cooled magnetization behavior, two well-defined temperatures can be associated with the appearance (disappearance) of the PME: T₁ indicates the characteristic temperature where the paramagnetic moment first appears (vanishes) and a lower temperature T_p defines the temperature where the positive moment no longer increases (begins to decrease). This indicates that the nature of the PME is reversible and not associated with flux motion.