Unanticipated proximity behavior in ferromagnet-superconductor heterostructures with controlled magnetic noncollinearity.
Unanticipated proximity behavior in ferromagnet-superconductor heterostructures with controlled magnetic noncollinearity.
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DOI：
10.1103/physrevlett.110.177001
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发表时间：
2013-04
影响因子：
8.6
通讯作者：
L. Zhu;Yaohua Liu;F. Bergeret;J. Pearson;S. Velthuis;S. Bader;J. Jiang
中科院分区：
文献类型：
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作者：
L. Zhu;Yaohua Liu;F. Bergeret;J. Pearson;S. Velthuis;S. Bader;J. Jiang
根据畴壁超导理论，铁磁-超导体（F/S）异质结构中的磁化非共线性可以提高超导转变温度（T(c)），或者当明确考虑自旋三重态库珀对时，可以抑制T(c)。我们研究了F/S结构中的邻近效应，其中F层是Sm-Co/Py交换弹簧双层层，S层是Nb。交换弹簧在Py层中包含一个单一的、可控的和可量化的畴壁。我们观察到，随着Py畴壁通过旋转磁场而日益扭曲，超导性的增强是非单调的，这与理论预测不同。我们已经排除了磁场和涡旋运动作为非单调行为的来源。这种意想不到的接近行为表明，在包含非共线磁化的F/S系统的理论处理中，尚未捕获新的物理。
Magnetization noncollinearity in ferromagnet-superconductor (F/S) heterostructures is expected to enhance the superconducting transition temperature (T(c)) according to the domain-wall superconductivity theory, or to suppress T(c) when spin-triplet Cooper pairs are explicitly considered. We study the proximity effect in F/S structures where the F layer is a Sm-Co/Py exchange-spring bilayer and the S layer is Nb. The exchange-spring contains a single, controllable and quantifiable domain wall in the Py layer. We observe an enhancement of superconductivity that is nonmonotonic as the Py domain wall is increasingly twisted via rotating a magnetic field, different from theoretical predictions. We have excluded magnetic fields and vortex motion as the source of the nonmonotonic behavior. This unanticipated proximity behavior suggests that new physics is yet to be captured in the theoretical treatments of F/S systems containing noncollinear magnetization.