Edge effect pinning in mesoscopic superconducting strips with non-uniform distribution of defects
Edge effect pinning in mesoscopic superconducting strips with non-uniform distribution of defects
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DOI：
10.1038/s41598-018-36285-4
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发表时间：
2019-01-18
影响因子：
4.6
通讯作者：
Sadovskyy, Ivan A.
中科院分区：
文献类型：
--
作者：
Kimmel, Gregory J.;Glatz, Andreas;Sadovskyy, Ivan A.
纳米尺寸的超导带和超导桥的输运特性是由表面和体钉扎的复杂相互作用决定的。在非常窄的桥的极限情况下，临界电流主要由其表面势垒定义，而在非常宽的带的相反情况下，它主要由其体钉扎特性决定。在这里，我们提出了一个详细的研究的中间制度，临界电流的确定，无论是随机放置的钉扎中心，并在外部磁场中的超导带的边缘的豆利文斯顿障碍。我们使用含时的Ginzburg-Landau方程来描述临界区的涡旋动力学和电流分布。我们的研究表明，虽然散装缺陷逮捕旋涡运动远离边缘，在其附近的缺陷促进旋涡渗透，从而抑制临界电流。我们确定的空间分布的缺陷优化的临界电流，并发现它是在一般的不均匀和不对称的：在涡流出口边缘的障碍影响的临界电流比涡流入口边缘强得多。此外，这种优化的缺陷分布比均匀无序超导膜的临界电流密度高30%以上。
Transport characteristics of nano-sized superconducting strips and bridges are determined by an intricate interplay of surface and bulk pinning. In the limiting case of a very narrow bridge, the critical current is mostly defined by its surface barrier, while in the opposite case of very wide strips it is dominated by its bulk pinning properties. Here we present a detailed study of the intermediate regime, where the critical current is determined, both, by randomly placed pinning centres and by the Bean-Livingston barrier at the edge of the superconducting strip in an external magnetic field. We use the time-dependent Ginzburg-Landau equations to describe the vortex dynamics and current distribution in the critical regime. Our studies reveal that while the bulk defects arrest vortex motion away from the edges, defects in their close vicinity promote vortex penetration, thus suppressing the critical current. We determine the spatial distribution of the defects optimizing the critical current and find that it is in general non-uniform and asymmetric: the barrier at the vortex-exit edge influence the critical current much stronger than the vortex-entrance edge. Furthermore, this optimized defect distribution has a more than 30% higher critical current density than a homogeneously disorder superconducting film.