Current-induced dendritic magnetic instability in superconducting MgB2 films

Abstract

Magneto-optical imaging reveals that in superconducting films of MgB2 a transport current creates avalanche-like flux dynamics where highly branching dendritic penetration patterns are formed. The instability is triggered when the current exceeds a threshold value, and the superconductor, shaped as a long strip, is initially in the critical state. The instability exists up to 19 K, which is a much wider temperature range than in previous experiments, where dendrites were formed by applying a magnetic field. The instability is believed to be of thermo-magnetic origin indicating that thermal stabilization may become crucial in applications of MgB2.

3 pages, 3 figures, resubmitted to Appl.Phys.Lett

References in corpus (6)

• High current-carrying capability in c-axis-oriented superconducting MgB2 thin films
• Suppression of Superconducting Critical Current Density by Small Flux Jumps in $Mg{B}_2$ Thin Films
• Dendritic flux patterns in MgB2 films
• Vortex avalanches and magnetic flux fragmentation in superconductors
• Flux Jumping and a Bulk-to-Granular Transition in the Magnetization of a Compacted and Sintered MgB2 Superconductor
• Superconductor strip with transport current: Magneto-optical study of current distribution and its relaxation

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• Avalanche-driven fractal flux distributions in NbN superconducting films
• Local threshold field for dendritic instability in superconducting MgB2 films
• Evidence of rf-driven branching of dendritic vortex avalanches in MgB2 microwave resonators
• Thermally driven inhibition of superconducting vortex avalanches
• Oscillatory regimes of the thermomagnetic instability in superconducting films
• Flux Dendrites of Opposite Polarity in Superconducting MgB${}_2$ rings observed with magneto-optical imaging
• Interplay of dendritic avalanches and gradual flux penetration in superconducting MgB2 films
• Active control of thermomagnetic avalanches in superconducting Nb films with tunable anisotropy