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Interplay of dendritic avalanches and gradual flux penetration in superconducting MgB2 films

D. V. Shantsev·P. E. Goa·F. L. Barkov·T. H. Johansen·W. N. Kang·S. I. Lee
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Abstract

Magneto-optical imaging was used to study a zero-field-cooled MgB2 film at 9.6K where in a slowly increasing field the flux penetrates by abrupt formation of large dendritic structures. Simultaneously, a gradual flux penetration takes place, eventually covering the dendrites, and a detailed analysis of this process is reported. We find an anomalously high gradient of the flux density across a dendrite branch, and a peak value that decreases as the applied field goes up. This unexpected behaviour is reproduced by flux creep simulations based on the non-local field-current relation in the perpendicular geometry. The simulations also provide indirect evidence that flux dendrites are formed at an elevated local temperature, consistent with a thermo-magnetic mechanism of the instability

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D. V. Shantsev, P. E. Goa, F. L. Barkov, T. H. Johansen, W. N. Kang, S. I. Lee. 2002-12-17. Interplay of dendritic avalanches and gradual flux penetration in superconducting MgB2 films. https://doi.org/10.1088/0953-2048%2F16%2F5%2F304

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