Abstract
Substitution of Pr for Y in the system depresses , with superconductivity disappearing for x≥0.5. The origin of this depression is still controversial, as is the valence state of the Pr ion. In order to study these problems, single-phase materials were prepared with x=0.0, 0.1, 0.2, 0.3, 0.35, 0.4 0.45, 0.5, 0.6, 0.7, 0.9, and 1.0. Under certain annealing conditions, these types of samples will phase separate into and , showing two transitions in the magnetization, but will still appear single phase from x-ray diffraction. We have overcome this problem through specific annealing conditions of time, temperature, and atmosphere. We find that the superconductivity is strongly suppressed as a function of Pr concentration, with a behavior which is consistent with the classical Abrikosov-Gor’kov pair-breaking theory. The critical fields versus T show a ‘‘bell’’-shaped behavior, which is consistent with the presence of magnetic pair-breaking interactions. The measured temperature dependence of the critical field, near , and the Pauli susceptibility, are used to estimate the physical parameters , , and γ.
- Received 10 April 1989
DOI:https://doi.org/10.1103/PhysRevB.40.4517
©1989 American Physical Society