Behavior of superconductivity in a Pb/Ag heterostructure
Behavior of superconductivity in a Pb/Ag heterostructure
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DOI：
10.1103/physrevb.100.094512
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发表时间：
2019-09
影响因子：
3.7
通讯作者：
H. Nam;Chendong Zhang;Woojoo Lee;Siyuan Zhu;Hongjun Gao;Q. Niu;G. Fiete;C. Shih
中科院分区：
文献类型：
--
作者：
H. Nam;Chendong Zhang;Woojoo Lee;Siyuan Zhu;Hongjun Gao;Q. Niu;G. Fiete;C. Shih
超导邻近效应是凝聚态物理中一个长期存在的重要课题。一个关键但尚未解决的问题是，界面和材料的细节决定的邻近效应的效率。在本文中，我们研究了外延生长的超导体/正常金属（SC-NM）异质结（Pb/Ag），并发现一个空间恒定的超导间隙确定的本地隧道光谱和磁响应测量，尽管个别铅和银外延层之间的高度失配的费米面和晶格常数和电子态密度的单独组件的巨大差异。均匀的超导间隙是相反的空间变化的对电位与不连续的接口理论预测为一个理想的SC-NM结和实验观察到以前在几个横向SC-NM结。我们的实验验证，在垂直的Pb/Ag异质结的界面上的电子的传输是足够高的，一个新的能带结构出现，即使在单粒子水平。我们的实验结果需要进一步的理论工作，以发展预测能力的邻近效应从现实的，材料相关的微观模型。
The superconducting proximity effect is a long-standing topic of great importance in condensed matter physics. A crucial but unresolved issue is which interfacial and material details determine the efficiency of the proximity effect. In this paper, we study an epitaxially grown superconductor/normal metal (SC-NM) heterostructure (Pb/Ag) and find a spatially constant superconducting gap determined by local tunneling spectroscopy and magnetoresponse measurements, despite the highly mismatched Fermi surfaces between individual Pb and Ag epitaxial layers and the large differences in the lattice constants and electronic densities of states in the separate components. The uniform superconducting gap is in contrast to the spatially varying pair potential with a discontinuity at the interface theoretically predicted for an ideal SC-NM junction and experimentally observed previously in several lateral SC-NM junctions. We experimentally verify that the transmission of electrons across the interface in the vertical Pb/Ag heterostructure is high enough that a new band structure emerges even at the single-particle level. Our experimental results call for further theoretical work in order to develop predictive power for the proximity effect starting from realistic, materially relevant microscopic models.