Reentrant stability of superconducting films and the vanishing of dendritic flux instability

Yurchenko, V. V.; Shantsev, D. V.; Johansen, T. H.; Nevala, M. R.; Maasilta, I. J.; Senapati, Kartik; Budhani, R. C.

doi:10.1103/physrevb.76.092504

Cited by 32 publications

(34 citation statements)

References 25 publications

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“…1 for a review. This dramatic avalanche phenomenon has been observed in films of many materials, such as Nb23, YBa 2 Cu 3 O x 4567, Pb8, MgB 2 9101112131415, Nb 3 Sn16, YNi 2 B 2 C17, NbN1819, and very recently also in α -MoGe20. It is today widely accepted that such events originate from a thermoelectromagnetic instability21, where an initial fluctuation sets some flux in motion and the dissipative displacement increases the local temperature.…”

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confidence: 83%

Lightning in superconductors

Vestgården

Shantsev

Galperin

et al. 2012

Sci Rep

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Crucially important for application of type-II superconductor films is the stability of the vortex matter – magnetic flux lines penetrating the material. If some vortices get detached from pinning centres, the energy dissipated by their motion will facilitate further depinning, and may trigger a massive electromagnetic breakdown. Up to now, the time-resolved behaviour of these ultra-fast events was essentially unknown. We report numerical simulation results revealing the detailed dynamics during breakdown as within nanoseconds it develops branching structures in the electromagnetic fields and temperature, with striking resemblance of atmospheric lightning. During a dendritic avalanche the superconductor is locally heated above its critical temperature, while electrical fields rise to several kV/m as the front propagates at instant speeds near up to 100 km/s. The numerical approach provides an efficient framework for understanding the ultra-fast coupled non-local dynamics of electromagnetic fields and dissipation in superconductor films.

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confidence: 83%

Lightning in superconductors

Vestgården

Shantsev

Galperin

et al. 2012

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“…The well-known dendritic flux avalanches caused by thermomagnetic instability have the characteristics of being irreproducible [15,24,25]. When a field sweep is repeated under the same experimental conditions, the flux patterns show essentially no overlap, suggesting that stochastic fluctuations play a main role.…”

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Quasi-One-Dimensional Intermittent Flux Behavior in Superconducting Films

et al. 2012

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Intermittent filamentary dynamics of the vortex matter in superconductors is found in films of YBa 2 Cu 3 O 7-deposited on tilted substrates. Deposition of this material on such substrates creates parallel channels of easy flux penetration when a magnetic field is applied perpendicular to the film. As the applied field is gradually increased, magneto-optical imaging reveals that flux penetrates via numerous quasi-one-dimensional jumps. The distribution of flux avalanche sizes follows a power law, and data collapse is obtained by finite-size scaling, with the depth of the flux front used as crossover length. The intermittent behavior shows no threshold value in the applied field, in contrast to conventional flux jumping. The results strongly suggest that the quasi-one-dimensional flux jumps are of a different nature than the thermomagnetic dendritic (branching) avalanches that are commonly found in superconducting films. Since the prediction of a regular vortex lattice in type-II superconductors [1], a wide variety of vortex systems has been thoroughly investigated [2,3]. The pronounced dependencies of the range and strength of the vortex-vortex interaction on temperature and magnetic field make the vortex matter a unique, tunable model system for probing the statistical properties of interacting systems. The behavior of the vortex matter is to a large extent also determined by its interaction with quenched disorder in the material, i.e., with microscopic defects that pin the vortices and therefore serve as pinning centers in the superconductor. The interplay between the pinning forces and the driving Lorentz force leads to formation of a metastable critical state [4], where the current density has a critical magnitude, j c , which corresponds to the maximal nondissipative current density.In films of YBa 2 Cu 3 O 7-(YBCO) grown epitaxially, i.e., with proper matching of crystal lattice parameters, on a substrate slightly tilted from a major crystal plane (vicinal films), self-organized arrays of planar defects (antiphase boundaries) are formed with a typical period of 2-5 nm [5]. The terrace structure of the surface is characterized by steps that are a few Å ngströms in height, and the steps provide well-oriented seeding sites for growth along the main axis (c axis) of the overlying YBCO film. Films grown on substrates with a tilt angle of close to 10 have better grain alignment and improved current-carrying ability [5,6]. There has been considerable interest in such films due to their potential application in Josephsonjunction design [7][8][9], in particular for highly sensitive detectors of electromagnetic radiation.The growth of YBCO films on tilted substrates is also known to produce planar defects, which become channels for easy vortex motion [5,6,10]. These channels are separated by 5-10 m and run parallel to the terrace structure, causing considerable anisotropy in both the flux penetration and the effective critical current. At low temperatures, where the anisotropy is most pronounced, the vortices are es...

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“…Recently we managed to put the existence of an upper threshold into the framework of the model described in the previous Section. 24 As follows from Eqs. ͑10͒ and ͑11͒, the threshold field depends nonmonotonically on the critical current density, as shown in Fig.…”

Section: Reentrant Stability Of Superconducting Filmsmentioning

confidence: 99%

Dendritic flux avalanches in superconducting films

Yurchenko

Johansen

Galperin

2009

Low Temperature Physics

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Thermomagnetic instability in general, and dendritic flux avalanches in particular, have attracted considerable attention of both scientists and engineers working on superconductor applications. Though being harmful for the performance of many superconducting devices, the avalanches provide a fruitful playground for experimental and theoretical studies of complex dynamics of the vortex matter. In this paper we report on the progress in understanding the mechanisms responsible for the development of the giant magnetic avalanches. We review recent results on magneto-optical imaging of the fingering instability in superconducting films and analyze them on the basis of recent theoretical model that establishes criteria for onset of the dendritic avalanches.

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Reentrant stability of superconducting films and the vanishing of dendritic flux instability

Cited by 32 publications

References 25 publications

Lightning in superconductors

Lightning in superconductors

Quasi-One-Dimensional Intermittent Flux Behavior in Superconducting Films

Dendritic flux avalanches in superconducting films

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