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Response of fractal penetration of magnetic flux to disorder landscape in superconducting films

Zuxin Ye·Qiang Li·W. D. Si·M. Suenaga·V. F. Solovyov·P. D. Johnson
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Abstract

Magnetic flux front and induction contours in superconducting YBa2Cu3O7-d films with defect size s ~ l (superconducting coherence length) and s > l are studied by magneto-optical imaging. Robust self-affine spatial correlation was observed using scaling analysis in the small pinning-dominated (s ~ l) disorderd films. The roughness exponent was determined to be ~ 0.66, independent of numbers of defects (or the film thickness). When the disorder landscape also included a distribution of large defects (s >> l), the flux front and induction contours exhibited self-similarity, with a fractal dimension to be ~ 1.33 using the box-counting method. The remarkably different flux penetration patterns were shown to be the manifestation of self-organized criticality at different length scales.

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Zuxin Ye, Qiang Li, W. D. Si, M. Suenaga, V. F. Solovyov, P. D. Johnson. 2005-08-20. Response of fractal penetration of magnetic flux to disorder landscape in superconducting films. https://doi.org/10.1103/physrevb.72.134514

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