Current-induced dendritic magnetic instability in superconducting MgB2 films

Bobyl, A. V.; Shantsev, D. V.; Johansen, T. H.; Kang, W. N.; Kim, H. J.; Choi, Eun Mi; Lee, S. I.

doi:10.1063/1.1485304

Cited by 55 publications

(44 citation statements)

References 19 publications

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“…[9][10][11][18][19][20][21][22][23][24][25] Such behavior is intimately correlated to thermomagnetic instabilities experienced by the material when heat generated by a sudden displacement of vortices cannot be dissipated, creating thus an increase in the local temperature. This warmer region, in turn, has its pinning capability reduced, being thus likely to host even more vortex motion, reinforcing the process.…”

Section: Resultsmentioning

confidence: 99%

Visualizing the ac magnetic susceptibility of superconducting films via magneto-optical imaging

et al. 2011

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We have established a link between the global ac response and the local flux distribution of superconducting films by combining magnetic ac susceptibility, dc magnetization, and magneto-optical measurements. The investigated samples are three Nb films: a plain specimen, used as a reference sample, and other two films patterned with square arrays of antidots. At low temperatures and small ac amplitudes of the excitation field, the Meissner screening prevents penetration of flux into the sample. Above a certain ac drive threshold, flux avalanches are triggered during the first cycle of the ac excitation. The subsequent periodic removal, inversion, and rise of flux occurs essentially through the already-created dendrites, giving rise to an ac susceptibility signal weakly dependent on the applied field. The intradendrite flux oscillation is followed, at higher values of the excitation field, by a more drastic process consisting of creation of new dendrites and antidendrites. In this more invasive regime, the ac susceptibility shows a clear field dependence. At higher temperatures a smooth penetration occurs, and the flux profile is characteristic of a critical state. We have also shown that the regime dominated by vortex avalanches can be reliably identified by ac susceptibility measurements.

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Section: Resultsmentioning

confidence: 99%

Visualizing the ac magnetic susceptibility of superconducting films via magneto-optical imaging

et al. 2011

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“…The critical current density determined from such m(H) curve appears significantly reduced compared to its "true" value that it would take in the absence of instabilities. The reduction can be as high as 50% as demonstrated for MgB 2 films, 16 where similar noisy magnetization curves have been measured in a wide range of T and H. 19 The dendritic avalanches can also be induced by pulses of transport current, 17 which threatens highcurrent applications. The thermo-magnetic origin of the dendritic instability is supported both by experiments 18 and computer simulations.…”

Section: -3mentioning

confidence: 95%

Dendritic flux avalanches in superconducting Nb3Sn films

et al. 2003

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The penetration of magnetic flux into a thin superconducting film of Nb3Sn with critical temperature 17.8K and critical current density 6MA/cm^2 was visualized using magneto-optical imaging. Below 8 K an avalanche-like flux penetration in form of big and branching dendritic structures was observed in response to increasing perpendicular applied field. When a growing dendritic branch meets a linear defect in the film, several scenarios were observed: the branch can turn and propagate along the defect, continue propagation right through it, or "tunnel" along a flux-filled defect and continue growth from its other end. The avalanches manifest themselves in numerous small and random jumps found in the magnetization curve.Comment: 3 pages, 4 figures, submitted to Cryogenics. Revision: M(H) data adde

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“…It is important to mention that the flux exit during the lowering of the field may be strongly inhomogeneous as well, leading to "antiavalanche" behavior, when the flux remains trapped inside despite lowering of the external field, and then leaves suddenly from the large area. Such instabilities of magnetic flux can result in the noisy behavior of magnetization [5,6] and they may lead to the suppression of the apparent critical current density j c [7], affecting adversely the devices build on the base of the superconducting films. Therefore, the understanding of the avalanche phenomenon is very important for practical applications of films.…”

Section: Introductionmentioning

confidence: 99%

Inhomogeneous Magnetic Field Penetration in Superconducting Niobium Films

Abal’osheva¹,

Abal’oshev²,

Cieplak³

et al. 2010

Acta Phys. Pol. A

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The peculiarities of magnetic field penetration in the form of fingering or dendritic instabilities are studied by magneto-optical technique in the niobium films of different thickness. It is observed that the reduction of Nb film thickness reduces the threshold field for instabilities, in agreement with the theoretical predictions. In addition, it is shown that the silver overlayer deposited on the top of Nb film leads also to the enhancement of instabilities, in marked contrast to the effect of gold or aluminum overlayers, which are known to suppress instabilities.

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Current-induced dendritic magnetic instability in superconducting MgB2 films

Cited by 55 publications

References 19 publications

Visualizing the ac magnetic susceptibility of superconducting films via magneto-optical imaging

Visualizing the ac magnetic susceptibility of superconducting films via magneto-optical imaging

Dendritic flux avalanches in superconducting Nb3Sn films

Inhomogeneous Magnetic Field Penetration in Superconducting Niobium Films

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