Superconductivity in one-atomic-layer metal films grown on Si(111)
Superconductivity in one-atomic-layer metal films grown on Si(111)
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DOI：
10.1038/nphys1499
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发表时间：
2010-02-01
期刊：
影响因子：
19.6
通讯作者：
Xue, Qi-Kun
中科院分区：
文献类型：
--
作者：
Zhang, Tong;Cheng, Peng;Xue, Qi-Kun
二维超导态是一种易受量子相位波动影响的物质脆弱态。虽然超导性已经在几层（1-10层）的超薄金属薄膜中被观察到，但仍然不知道单层有序金属原子是否可以超导，这代表了晶体薄膜的最终二维极限。在这里，我们报告了扫描隧道显微镜对在Si（111）衬底上外延生长的Pb和In单原子层的测量，并明确地证明了超导性确实存在于这样的二维极端。当原子面密度n = 10.44 Pb原子nm（-2）时，薄膜的超导转变温度分别为1.83 K、1.52 K和3.18 K，分别为n = 9.40 Pb原子nm（-2）和n = 9.40 In原子nm（-2）。我们通过磁场下超导涡旋的存在证实了超导性的存在。原位角分辨光发射光谱测量表明，观察到的超导性是由于Pb-Pb （In-In）金属和Pb-Si （In- si）共价键之间的相互作用。
The two-dimensional (2D) superconducting state is a fragile state of matter susceptible to quantum phase fluctuations. Although superconductivity has been observed in ultrathin metal films down to a few layers(1-10), it is still not known whether a single layer of ordered metal atoms, which represents the ultimate 2D limit of a crystalline film, could be superconducting. Here we report scanning tunnelling microscopy measurements on single atomic layers of Pb and In grown epitaxially on Si(111) substrate, and demonstrate unambiguously that superconductivity does exist at such a 2D extreme. The film shows a superconducting transition temperature of 1.83 K for an atom areal density n = 10.44 Pb atoms nm(-2), 1.52 K for n = 9.40 Pb atoms nm(-2) and 3.18 K for n = 9.40 In atoms nm(-2), respectively. We confirm the occurrence of superconductivity by the presence of superconducting vortices under magnetic field. In situ angle-resolved photoemission spectroscopy measurements reveal that the observed superconductivity is due to the interplay between the Pb-Pb (In-In) metallic and the Pb-Si (In-Si) covalent bondings.