Optically Triggered Chaotic Vortex Avalanches in Superconducting YBa2Cu3O7−x Films

Abstract

Flux avalanche is commonly found in type II superconductors, and this event is always featured as being unpredictable and having ultrafast development with time. It is difficult to capture dynamically by any experimental method available today. Here, we propose a hypervelocity magnetic-optical system with two optical branches; one branch can trigger a dendritic flux avalanche in a superconducting film, and the other is capable of producing continuous multiexposure to record the lightning avalanche process. In contrast with some traditional trigger models, the present method realizes control of the position where the flux avalanche takes place. Second, we study the sensitive dependence on initial conditions of the present flux avalanche and find a series of positive Lyapunov exponents between two adjacent trajectories, which can be considered direct evidence for the chaotic dynamics in this kind of avalanche. Moreover, we reveal that, whether the laser spot is in the Meissner state or the mixed state, avalanches always penetrate from the edge of the superconducting film to the Meissner region, instead of occurring around the laser spot. This behavior clearly demonstrates that the presented avalanche is driven by the magnetic pressure force, which suggests that the optically triggered vortex avalanche possesses a different mechanism from that of the thermomagnetic avalanches commonly found in superconducting films.

Source-reported materials — not catalogue approval

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