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Volume 35, Issue 6, June 2009
- SUPERCONDUCTIVITY, INCLUDING HIGH-TEMPERATURE SUPERCONDUCTIVITY
35(2009); http://dx.doi.org/10.1063/1.3151990View Description Hide Description
The mixed-state superconducting properties of bulk and , prepared by in situ solid state reaction, are investigated. Analysis of the mixed-state parameters, such as the upper critical field, the coherence length, and the Ginzburg-Landau parameter, proves that is a high- type-II superconductor in the dirty limit, while corresponds to that in the moderately clean limit. It is shown that the grain-boundary pinning realized in fine-grained doped polycrystals is of the anisotropic rather than the electron-scattering type. The field-cooled temperature dependences of the magnetic moment reveal a transition of the samples to the paramagnetic state at certain applied magnetic fields, which is treated as manifestation of the paramagnetic Meissner effect. The experimental results are discussed on the base of modern theoretical approaches.