Publication Details

Colauto, F., Carmo, D., De Andrade, A. M. H., Oliveira, A. A. M., Ortiz, W. A. & Johansen, T. H. (2017). Anisotropic thermomagnetic avalanche activity in field-cooled superconducting films. Physical Review B: Condensed Matter and Materials Physics, 96 (6), 060506-1-060506-5.


The electrodynamic behavior of isotropic superconducting Nb films cooled below their critical temperature in the presence of in-plane applied magnetic fields is investigated using magneto-optical imaging. A specially designed local flux injector is used to show that the frozen-in in-plane vortices strongly guide and enhance the penetration of perpendicular vortices, whereas their penetration across the array of in-plane vortices is essentially unchanged. This result provides the key to understanding why field-cooled square superconducting films show anisotropic nucleation of flux avalanches (jumps) along the four edges. The explanation is based on an analytical model for thermomagnetic avalanche nucleation in type-II superconducting films, and allows one to understand the entire scenario of different flux dynamics observed experimentally.



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