Artificial vortex pinning arrays in superconducting films deposited on highly ordered anodic alumina templates
Artificial vortex pinning arrays in superconducting films deposited on highly ordered anodic alumina templates
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沉积在高度有序阳极氧化铝模板上的超导薄膜中的人工涡旋钉扎阵列
作者：
L. Piraux;X. Hallet
描述了在超导 NbN 薄膜中创建周期性涡旋钉扎中心的简单过程。我们报告了三种不同的策略，其中涉及使用高度有序的氧化铝模板。在这种方法中，NbN薄膜沉积在由纳米孔三角形阵列组成的模板的多孔面上，或者沉积在由阻挡层形成的三角形凸块阵列上，甚至沉积在通过电化学沉积获得的垂直取向的铁磁纳米线阵列的顶部上，从而形成超导体-铁磁体混合体。在所有情况下，有序模板允许 NbN 薄膜在其生长过程中形成周期性钉扎阵列。孔间（或凸块间）距离范围在50和100 nm之间，可调节孔（或线）直径在30和60 nm之间变化。在高达 2.5 T 的温度下已观察到许多匹配效应，并且在低温下仍能保持。这些场明显高于通过光刻技术制造的周期性钉扎阵列的典型场，这反映了纳米结构超导体通过使用自组织生长来增强大场和温度范围内的涡旋钉扎的优势。
A simple procedure is described for creating periodic vortex pinning centers in thin superconducting NbN films. We report on three different strategies which involve the use of highly ordered alumina templates. In this approach, NbN thin films are deposited either on the porous face of the template made of a triangular array of nanoholes or on the triangular array of bumps formed by the barrier layer or even on the top of perpendicularly oriented ferromagnetic nanowire arrays obtained by electrochemical deposition, thus forming superconductor–ferromagnet hybrids. In all cases, the ordered template allows NbN films to form a periodic pinning array during its growth. The interpore (or inter-bump) distance ranged between 50 and 100 nm and adjustable pore (or wire) diameter was varied between 30 and 60 nm. Numerous matching effects have been observed up to 2.5 T and are maintained at low temperature. These fields are considerably higher than those typical for periodic pinning arrays made by lithographic techniques, which reflects the benefits of nanostructuring superconductors by using self-organized growth to enhance vortex pinning in a large field and temperature range.