Publications in Scientific Journals:

M. Eisterer, M. Zehetmayer, H. W. Weber, J. Jiang, J.D. Weiss, A. Yamamoto, E.E. Hellstrom, D.C. Larbalestier, N.D. Zhigadlo, J. Karpinski:
"Disorder effects and current percolation in FeAs-based superconductors";
Superconductor Science and Technology, 23 (2010), 054006 - 054012.

English abstract:
We report the influence of atomic disorder introduced by sequential neutron irradiation on the
basic superconducting properties, flux pinning and grain connectivity. Two different
polycrystalline Sm-1111 samples (SmFeAsO1−xFx) and two Ba-122 single crystals
(BaFe1.8Co0.2As2) were investigated. The monotonic decrease of the transition temperature
with neutron fluence degrades the upper critical field, at least in the investigated temperature
region. Pinning, on the other hand, is largely improved, with a different optimal defect
concentration (fluence) in the two materials. The analysis of the current flow in the
polycrystalline samples reveals weak link behavior in the majority of grain connections and the
existence of stronger grain connections. The density of the latter seems to be close to the
percolation threshold (i.e. the minimum fraction for a continuous current path). Both types of
connections are sensitive to disorder and degrade upon neutron irradiation.

"Official" electronic version of the publication (accessed through its Digital Object Identifier - DOI)

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