Phase-Sensitive Evidence for the Sign-Reversal s± Symmetry of the Order Parameter in an Iron-Pnictide Superconductor Using Nb/Ba1-xNaxFe2As2 Josephson Junctions
Phase-Sensitive Evidence for the Sign-Reversal s± Symmetry of the Order Parameter in an Iron-Pnictide Superconductor Using Nb/Ba1-xNaxFe2As2 Josephson Junctions
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DOI：
10.1103/physrevlett.120.067001
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发表时间：
2018-02-06
影响因子：
8.6
通讯作者：
Krasnov, V. M.
中科院分区：
文献类型：
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作者：
Kalenyuk, A. A.;Pagliero, A.;Krasnov, V. M.
约瑟夫森电流为探测对对称性提供了一种相敏工具。在这里，我们提出了一个实验研究高质量的约瑟夫森结之间的传统s波超导体Nb和多波段铁镍酸盐Ba1-xNaxFe2As2。结表现出足够大的临界电流密度，以排除pnictide中顺序参数的d波对称性。然而，IcRn产品非常小。类似或等于3 mu V，这也不符合保符号s（++）对称性。我们认为，较小的IcRn值，以及它不寻常的温度依赖性，为Ba1-xNaxFe2As2中序参量的符号反转s（+/-）对称性提供了证据。我们得出的结论是，正是我们的连接的相敏性导致了信号反转带的超电流几乎完全（低于百分之一）消除。
Josephson current provides a phase-sensitive tool for probing the pairing symmetry. Here we present an experimental study of high-quality Josephson junctions between a conventional s-wave superconductor Nb and a multiband iron-pnictide Ba1-xNaxFe2As2. Junctions exhibit a large enough critical current density to preclude the d-wave symmetry of the order parameter in the pnictide. However, the IcRn product is very small. similar or equal to 3 mu V, which is not consistent with the sign-preserving s(++) symmetry either. We argue that the small IcRn value, along with its unusual temperature dependence, provides evidence for the sign-reversal s(+/-) symmetry of the order parameter in Ba1-xNaxFe2As2. We conclude that it is the phase sensitivity of our junctions that leads to an almost complete (below a subpercent) cancellation of supercurrents from sign-reversal bands in the pnictide.