Strain-Controlled Superconductivity in Few-Layer NbSe2
Strain-Controlled Superconductivity in Few-Layer NbSe2
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DOI：
10.1021/acsami.0c08804
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发表时间：
2020-08-26
影响因子：
9.5
通讯作者：
Wei, Peng
中科院分区：
文献类型：
--
作者：
Chen, Cliff;Das, Protik;Wei, Peng
低维材料中超导性的可控可调性可能使新的量子器件成为可能。特别是在三重态或拓扑超导体中，隧道器件如约瑟夫森结等可以展示奇异的功能。隧道势垒，一种隔离两个超导体的绝缘或正常材料层，是连接的关键组成部分。薄层的NbSe2表现为具有强自旋轨道耦合的超导体，在大磁场的驱动下可以产生拓扑超导性。在这里，我们展示了外延生长的具有晶圆尺度均匀性的少层NbSe2在绝缘衬底上的超导体-绝缘体转变。我们提供了绝缘相的电输运、拉曼光谱、横截面透射电子显微镜和x射线衍射表征。我们发现超导体-绝缘体的转变是由应变驱动的，应变也会导致拉曼模式的特征能量转移。我们的观察为高质量的异质结隧道屏障无缝地嵌入到外延NbSe2本身铺平了道路，从而为基于超导体的量子电子学提供了高度可扩展的隧道器件。
The controlled tunability of superconductivity in low-dimensional materials may enable new quantum devices. Particularly in triplet or topological superconductors, tunneling devices such as Josephson junctions, etc., can demonstrate exotic functionalities. The tunnel barrier, an insulating or normal material layer separating two superconductors, is a key component for the junctions. Thin layers of NbSe2 have been shown as a superconductor with strong spin orbit coupling, which can give rise to topological superconductivity if driven by a large magnetic exchange field. Here we demonstrate the superconductor- insulator transitions in epitaxially grown few-layer NbSe2 with wafer-scale uniformity on insulating substrates. We provide the electrical transport, Raman spectroscopy, cross-sectional transmission electron microscopy, and X-ray diffraction characterizations of the insulating phase. We show that the superconductor-insulator transition is driven by strain, which also causes characteristic energy shifts of the Raman modes. Our observation paves the way for high-quality heterojunction tunnel barriers to be seamlessly built into epitaxial NbSe2 itself, thereby enabling highly scalable tunneling devices for superconductor-based quantum electronics.