Ray optics in flux avalanche propagation in superconducting films

Abstract

Experimental evidence of wave properties of dendritic flux avalanches in superconducting films is reported. Using magneto-optical imaging the propagation of dendrites across boundaries between a bare NbN film and areas coated by a Cu-layer was visualized, and it was found that the propagation is refracted in full quantitative agreement with Snell's law. For the studied film of 170 nm thickness and a 0.9 mkm thick metal layer, the refractive index was close to n=1.4. The origin of the refraction is believed to be caused by the dendrites propagating as an electromagnetic shock wave, similar to damped modes considered previously for normal metals. The analogy is justified by the large dissipation during the avalanches raising the local temperature significantly. Additional time-resolved measurements of voltage pulses generated by segments of the dendrites traversing an electrode confirm the consistency of the adapted physical picture.

arXiv comment4 pages, 4 figures

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Cited by in corpus (5)

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• Nucleation and propagation of thermomagnetic avalanches in thin-film superconductors
• Cascade dynamics of thermomagnetic avalanches in superconducting films with holes
• The importance of thermal gradients on the vortex dynamics and magnetic behavior of mesoscopic superconducting samples
• Spin texture on top of vortex avalanches in Nb/Al_2O_3/Co thin film heterostructures