In this letter, the electromagnetic response of the NdFeAsO1-0.14F0.14 (T (c) =49 K) superconductor system, characterized by FeAs and NdO alternating layers, has been compared with that of FeSe0.88. We have studied the flux dynamics of these two systems by means of ac multi-harmonic magnetic susceptibility. The analysis shows that although characterized by larger thermal fluctuations due to its higher T (c) , NdFeAsO1-0.14F0.14 exhibits a stronger pinning force relative to FeSe0.88. The further Irreversibility Line (IL) analysis also points out that both superconductors have a 3D flux pinning behavior. We associate the stronger pinning force in the NdFeAsO1-0.14F0.14 structure to the presence of the extra NdO layer. Different pinning contributions can be associated to the structural stress associated to FeAs superconducting layers and/or to the Nd3+ ions magnetic moment (mu similar to 3.6 mu(B)) contribution on the flux cores. We will also show that these pinning are over imposed to a weak collective contribution due to the dopant F atoms.
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|Titolo:||Influence of the extra layer on the transport properties of NdFeAsO1-0.14F0.14 and FeSe0.88 superconductors from magneto dynamic analysis|
|Data di pubblicazione:||2012|
|Appartiene alla tipologia:||01a Articolo in rivista|