A spin triplet supercurrent through the half-metallic ferromagnet CrO2
A spin triplet supercurrent through the half-metallic ferromagnet CrO2
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DOI：
10.1038/nature04499
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发表时间：
2006-02-16
期刊：
影响因子：
64.8
通讯作者：
Gupta, A
中科院分区：
文献类型：
--
作者：
Keizer, RS;Goennenwein, STB;Gupta, A
一般来说，传统的超导性不应该发生在铁磁体中，尽管它已经在压力下的铁中被发现(1)。此外，理论预测电流总是由处于自旋单线态的电子对携带(2)，因此传统的超导性在与铁磁体接触时衰减得非常快，而铁磁体通常禁止单线态电子对的存在。据预测，如果在铁磁体中可以诱导自旋三重态超导性，则不会发生这种快速的空间衰减（3,4）。在这里，我们报道了通过强铁磁体CrO2的约瑟夫森超电流，由此我们推断它是一个自旋三重态超电流。我们的实验设置不同于先前预测的设想，但我们得出结论，我们结果的潜在物理解释是界面上自旋单重态对到自旋三重态的转换。超电流可以随磁化方向切换，类似于自旋阀晶体管，因此可以实现磁化控制的约瑟夫森结。
In general, conventional superconductivity should not occur in a ferromagnet, though it has been seen in iron under pressure(1). Moreover, theory predicts that the current is always carried by pairs of electrons in a spin singlet state(2), so conventional superconductivity decays very rapidly when in contact with a ferromagnet, which normally prohibits the existence of singlet pairs. It has been predicted that this rapid spatial decay would not occur if spin triplet superconductivity could be induced in the ferromagnet(3,4). Here we report a Josephson supercurrent through the strong ferromagnet CrO2, from which we infer that it is a spin triplet supercurrent. Our experimental set-up is different from those envisaged in the earlier predictions, but we conclude that the underlying physical explanation for our result is a conversion from spin singlet pairs to spin triplets at the interface. The supercurrent can be switched with the direction of the magnetization, analogous to spin valve transistors, and therefore could enable magnetization-controlled Josephson junctions.