Cracks and critical current
Cracks and critical current
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DOI：
10.1063/1.349298
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发表时间：
1991-09
影响因子：
3.2
通讯作者：
Seong-Gon Kim;P. Duxbury
中科院分区：
文献类型：
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作者：
Seong-Gon Kim;P. Duxbury
在超导体中，裂缝（宽度为w￣ξ）能有效地增强局部超电流，我们利用二维伦敦理论计算了这些超电流热点的大小作为裂缝长度a和伦敦穿透深度λ的函数。在λ→∞极限和恒定注入电流密度下，我们证明了该二维解对于含有贯通裂纹的薄膜中的电流流动也是精确的。我们认为，大的局部超流附近的表面裂纹成核涡的产生。如果通量固定足够弱，这些涡旋就会在较大的局部洛伦兹力的影响下流动。这样产生的耗散会导致观测到的临界电流的减小。如果钉钉是适度的，在裂纹尖端附近形成核的第一个附加涡被钉住，在一个我们标记为ρ的区域，钉钉区。在薄膜中存在穿透裂纹的情况下，我们认为jc(a)减小为jc(a)/jc(0) ~ (ρ/a)x（对于a/L≪1），其中L是薄膜宽度，x =1/2对于简单的…
In superconductors, cracks (of width w ≳ ξs) are effective in enhancing local supercurrent, and we calculate the size of these supercurrent hot spots as a function of the crack length a and the London penetration depth λ using the two‐dimensional (2D) London theory. In the λ→∞ limit and constant injected current density, we show that this 2D solution is also exact for the current flow in a thin film containing a through crack. We argue that large local supercurrents near a surface crack nucleate vortex creation. If flux pinning is weak enough these vortices flow under the influence of the large local Lorentz force. The dissipation so produced can lead to a reduction in observed critical current. If flux pinning is moderate, the first additional vortices nucleated near the crack tip are pinned, in a region we label ρ, the flux pinning zone. In the case of a through crack in a thin film, we then argue that jc(a) reduces as jc(a)/jc(0) ∼ (ρ/a)x (for a/L≪1), where L is the film width and x =1/2 for the simple...