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Influence of the upper critical field anisotropy on the transport properties of polycrystalline MgB$_{2}$

M. Eisterer·C. Krutzler·H. W. Weber
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Abstract

The intrinsic properties of MgB$_2$ form the basis for all applications of this superconductor. We wish to emphasize that the application range of polycrystalline MgB$_2$ is limited by the upper critical field H$_{c2}$ and its anisotropy. In wires or tapes, the MgB$_2$ grains are randomly oriented or only slightly textured and the anisotropy of the upper critical field leads to different transport properties in different grains, if a magnetic field is applied and the current transport becomes percolative. The irreversibility line is caused by the disappearance of a continuous superconducting current path and not by depinning as in high temperature superconductors. Based on a percolation model, we demonstrate how changes of the upper critical field and its anisotropy and how changes of flux pinning will influence the critical currents of a wire or a tape. These predictions are compared to results of neutron irradiation experiments, where these parameters were changed systematically.

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M. Eisterer, C. Krutzler, H. W. Weber. 2005-06-22. Influence of the upper critical field anisotropy on the transport properties of polycrystalline MgB$_{2}$. https://doi.org/10.1063/1.1997288

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