PrBa2Cu3O7-y: Superconducting or anomalously magnetic?

In PrBa2Cu3O7-y (Pr123) single crystals grown by the flux method the kink in the magnetic susceptibility χab(T), connected with antiferromagnetic ordering of Pr, disappears after field cooling (FC) in a field H parallel ab-plane whereas the kink in χc(T) remains unchanged after FC in H parallel c-axis. This seems to be connected with the coupling between the Pr and Cu(2) sublattices. The Curie constant C determined from the data reported for superconducting Pr123 crystals grown by the traveling-solvent floating zone (TSFZ) method (Zou et al, Phys. Rev. Lett., 80, 1074 (1998)) is about one half of that for the flux-grown non-superconducting crystals. Thus, they propose that concentration of Pr in TSFZ crystals seems to be about one half of the nominal concentration for Pr123. Therefore, they propose that superconductivity in TSFZ samples is connected most probably with the partial substitution of Pr by nonmagnetic Ba