Evidence for Nonlocal Electrodynamics in Planar Josephson Junctions
Evidence for Nonlocal Electrodynamics in Planar Josephson Junctions
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DOI：
10.1103/physrevlett.111.117002
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发表时间：
2013-09-13
影响因子：
8.6
通讯作者：
Krasnov, V. M.
中科院分区：
文献类型：
--
作者：
Boris, A. A.;Rydh, A.;Krasnov, V. M.
我们研究了两种平面Josephson结的临界电流调制I-c(H)的温度依赖性：低t -c Nb/CuNi/Nb和高t -c YBa2Cu3O7-delta双晶晶界结。在低温度下，两个结点都表现出常规的行为，用局部正弦戈登方程来描述。然而，在升高的温度下，行为变得质的不同：I-c(H)调制场Delta H几乎与温度无关，并且Delta H和约瑟夫森涡穿透的临界场在T-c时都没有消失。这种不寻常的行为很好地符合非局部电动力学结的理论预测。我们从数据中提取了伦敦穿透深度λ的绝对值，并表明当λ (T)大于电极厚度时，随着T的增加，从局部到非局部电动力学会发生交叉。
We study the temperature dependence of the critical current modulation I-c(H) for two types of planar Josephson junctions: a low-T-c Nb/CuNi/Nb and a high-T-c YBa2Cu3O7-delta bicrystal grain-boundary junction. At low T both junctions exhibit a conventional behavior, described by the local sine-Gordon equation. However, at elevated T the behavior becomes qualitatively different: the I-c(H) modulation field Delta H becomes almost T independent and neither Delta H nor the critical field for the penetration of Josephson vortices vanish at T-c. Such an unusual behavior is in good agreement with theoretical predictions for junctions with nonlocal electrodynamics. We extract absolute values of the London penetration depth lambda from our data and show that a crossover from local to nonlocal electrodynamics occurs with increasing T when lambda(T) becomes larger than the electrode thickness.