Comparative study of type-II superconducting properties in polycrystalline NdFeAsO sub(0.88)F sub(0.12) prepared by different methods

Polycrystalline NdFeAsO sub(0.88)F sub(0.12) superconductors prepared by high pressure (HP) and ambient pressure (AP) methods were comparatively studied by magnetization and transport measurements. Upper critical field H sub(c2), irreversibility field H sub(irr) and the anisotropy parameter were est...

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Bibliographic Details
Published in:Physica. C, Superconductivity Superconductivity, 2010-12, Vol.470 (22), p.2051-2056
Main Authors: Ding, Y, Sun, Y, Wang, X D, Wang, H C, Shi, Z X, Ren, Z A, Yang, J, Lu, W
Format: Article
Language:English
Subjects:
Anisotropy
Critical current density
Hysteresis
Hysteresis loops
Inhomogeneity
Magnetization
Superconductivity
Transport
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Summary:Polycrystalline NdFeAsO sub(0.88)F sub(0.12) superconductors prepared by high pressure (HP) and ambient pressure (AP) methods were comparatively studied by magnetization and transport measurements. Upper critical field H sub(c2), irreversibility field H sub(irr) and the anisotropy parameter were estimated from resistance transition curves. The broadening of transition width was observed, and was ascribed to both H sub(c2) anisotropy and superconductivity inhomogeneity of samples. Magnetic hysteresis loops (MHLs) in low fields were measured to detect the trace of weak-link behavior. The reclosed hysteresis loops in low fields indicate that there are weak links in both samples. Magnetization critical current density J sub(cm) were derived from MHLs. Sample HP shows higher J sub(cm) than sample AP. Direct transport I-V measurements show that the transport critical current density J sub(ct) are very low but persist up to 9 T, suggesting intrinsic strong-link existing in both samples.
ISSN:0921-4534
DOI:10.1016/j.physc.2010.09.012