Proximity effect and Josephson current in clean strong/weak/strong superconducting trilayers
Proximity effect and Josephson current in clean strong/weak/strong superconducting trilayers
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DOI：
10.1103/physrevb.73.014503
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发表时间：
2006-01-01
影响因子：
3.7
通讯作者：
Marsiglio, F
中科院分区：
文献类型：
--
作者：
Covaci, L;Marsiglio, F
最近通过LSCO/LCO/LSCO薄膜测量的约瑟夫森临界电流显示出异常大的接近效应。使用紧密结合哈密顿量的Bogoliubov-de Gennes方程，我们描述了临界温度为T-c的超导体和临界温度为T-c（‘）的超导体之间的弱链接中的邻近效应，其中T-c > T-c（’）。弱链（N-'）因此是高于其自身临界温度的超导体，超导区域被认为具有s波或d波对称。我们注意到，由于弱环节中超导相关的存在，邻近效应得到了增强。计算了直流约瑟夫森电流，我们得到了温度大于T-c（'）的非零值，弱链路的大小几乎可以比传统相干长度大一个数量级。考虑到N '层中的超导口袋，我们表明这可以通过有效缩短弱链接而导致对约瑟夫森临界电流的更大影响。
Recent measurements of the Josephson critical current through LSCO/LCO/LSCO thin films showed an unusually large proximity effect. Using the Bogoliubov-de Gennes equations for a tight-binding Hamiltonian we describe the proximity effect in weak links between a superconductor with critical temperature T-c and one with critical temperature T-c('), where T-c > T-c('). The weak link (N-') is therefore a superconductor above its own critical temperature and the superconducting regions are considered to have either s-wave or d-wave symmetry. We note that the proximity effect is enhanced due to the presence of superconducting correlations in the weak link. The dc Josephson current is calculated, and we obtain a nonzero value for temperatures greater than T-c(') for sizes of the weak links that can be almost an order of magnitude greater than the conventional coherence length. Considering pockets of superconductivity in the N-' layer, we show that this can lead to an even larger effect on the Josephson critical current by effectively shortening the weak link.