Metal frame as local protection of superconducting films from thermomagnetic avalanches
Mikheenko, P., Vestgården, J. I., Chaudhuri, S., Maasilta, I., Galperin, M., & Johansen, T. H. (2016). Metal frame as local protection of superconducting films from thermomagnetic avalanches. AIP Advances, 6, 035304. doi:10.1063/1.4943549 Retrieved from http://arxiv.org/abs/1601.00425
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Thermomagnetic avalanches in superconducting films propagating extremely fast
while forming unpredictable patterns, represent a serious threat for the performance
of devices based on such materials. It is shown here that a normal-metal frame
surrounding a selected region inside the film area can provide efficient protection
from the avalanches during their propagation stage. Protective behavior is
confirmed by magneto-optical imaging experiments on NbN films equipped with
Cu and Al frames, and also by performing numerical simulations. Experimentally,
it is found that while conventional flux creep is not affected by the frames,
the dendritic avalanches are partially or fully screened by them. The level of
screening depends on the ratio of the sheet conductance of the metal and the
superconductor in the resistive state, and for ratios much larger than unity the
screening is very efficient.