Superheating in coated niobium

Junginger, T. and Wasserman, W. and Laxdal, R. E. (2017) Superheating in coated niobium. Superconductor Science and Technology, 30 (12). ISSN 0953-2048

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Using muon spin rotation it is shown that the field of first flux penetration Hentry in Nb is enhanced by about 30% if coated with an overlayer of Nb3Sn or MgB2. This is consistent with an increase from the lower critical magnetic field Hc1 up to the superheating field Hsh of the Nb substrate. In the experiments presented here coatings of Nb3Sn and MgB2 with a thickness between 50 and 2000 nm have been tested. Hentry does not depend on material or thickness. This suggests that the energy barrier at the boundary between the two materials prevents flux entry up to Hsh of the substrate. A mechanism consistent with these findings is that the proximity effect recovers the stability of the energy barrier for flux penetration, which is suppressed by defects for uncoated samples. Additionally, a low temperature baked Nb sample has been tested. Here a 6% increase of Hentry was found, also pushing Hentry beyond Hc1.

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Journal Article
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Superconductor Science and Technology
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This is an author-created, un-copyedited version of an article accepted for publication/published in Superconductor Science and Technology. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at doi: 10.1088/1361-6668/aa8e3a
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27 Mar 2018 15:46
Last Modified:
12 Mar 2023 01:12