Rare-region onset of superconductivity in niobium nanoislands
Rare-region onset of superconductivity in niobium nanoislands
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DOI：
10.1103/physrevb.101.035409
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发表时间：
2020-01
影响因子：
3.7
通讯作者：
M. Durkin;Rita Garrido-Menacho;S. Gopalakrishnan;N. Jaggi;J. Kwon;J. Zuo;N. Mason
中科院分区：
文献类型：
--
作者：
M. Durkin;Rita Garrido-Menacho;S. Gopalakrishnan;N. Jaggi;J. Kwon;J. Zuo;N. Mason
我们报告了孤立的Nb纳米岛（直径600-2500 nm）的超导特性的测量结果，并解释了它们在稀有区域开始效应方面的不寻常行为，预测随机金属超导体颗粒系统[B。Spivak、P. Oreto和S. A. Kivelson，Phys. Rev. B 77，214523（2008）10.1103/PhysRevB.77.214523]。我们发现，即使在大的岛直径，超过1μm的岛强烈抑制。这种行为是出乎意料的，因为传统的小晶粒超导理论预测只有在小两个数量级的长度尺度上才能抑制。此外，对于名义上相同的岛屿，我们观察到大的岛屿之间的变化。这两个实验观察，再加上直接测量的晶粒分布，使用透射电子显微镜，导电原子力显微镜和计算机模拟，为我们的图片中，超导性的开始在一个岛上与其最大的组成颗粒的转变温度相一致，然后蔓延到其他晶粒由于邻近耦合的证据。
We report measurements of the superconducting properties of isolated Nb nanoislands (600–2500 nm diameters) and explain their unusual behavior in terms of rare-region onset effects, predicted for random metal-superconductor granular systems [B. Spivak, P. Oreto, and S. A. Kivelson, Phys. Rev. B 77, 214523 (2008)10.1103/PhysRevB.77.214523]. We find that the islandis strongly suppressed even at large island diameters, exceeding 1μm. This behavior is unexpected given that conventional theories of superconductivity in small grains predict suppression ofonly at a length scale that is two orders of magnitude smaller. In addition, we observe large island-to-island variations infor nominally identical islands. These two experimental observations, coupled with direct measurement of grain distribution using transmission electron microscopy, conductive atomic force microscopy, and computer simulations, provide evidence for our picture in which the onset of superconductivity on an island coincides with the transition temperature of its largest constituent grain, and then spreads to other grains due to proximity coupling.