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arXiv 1209.5355cond-mat.supr-con
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螺旋磁/铁磁约瑟夫森结中依赖于磁耦合的自旋三重态超电流

Magnetic-coupling-dependent spin-triplet supercurrents in helimagnet/ferromagnet Josephson junctions

Gábor B. Halász, M. G. Blamire, J. W. A. Robinson

摘要:

在过去的一年里,在证明与单线态超导体耦合的铁磁体中存在长程自旋三重态超电流方面的实验成就为新的有趣的物理学和应用开辟了可能性。Today 64(1),43(2011)]。本课题组报道了将三重态超电流注入磁性均匀的铁磁体(Co)中,并将其夹在两个氦磁体/超导体(Ho/Nb)双层膜之间,形成Nb/Ho/Co/Ho/Nb型约瑟夫森器件。在Ho层厚度的函数中,发现超电流以复杂的方式调制,该方式似乎取决于Ho的磁结构。为了理解这种不寻常的行为,我们利用Eilenberger方程从理论上研究了具有Helimagnet/Ferromagnet/Helimagnet(HM/F/HM)势垒的理想Josephson器件在清洁极限下的特性;我们特别指出,可以穿过势垒的最大三重态超电流将取决于非如果HM层和F层在它们的界面处磁交换耦合,则在HM层的厚度上单调。

英文摘要:

The experimental achievements during the past year in demonstrating the existence of long-ranged spin-triplet supercurrents in ferromagnets proximity coupled to singlet superconductors open up the possibility for new interesting physics and applications [for a review, see M. Eschrig, Phys. Today 64(1), 43 (2011)]. Our group reported the injection of triplet supercurrents into a magnetically uniform ferromagnet (Co) by sandwiching it between two helimagnet/superconductor (Ho/Nb) bilayers to form a Nb/Ho/Co/Ho/Nb-type Josephson device. In the function of the Ho layer thicknesses, the supercurrent was found to modulate in a complex way that seemed to depend on the magnetic structure of Ho. To understand this unusual behavior, we have theoretically studied the properties of an ideal Josephson device with a helimagnet/ferromagnet/helimagnet (HM/F/HM) barrier in the clean limit using the Eilenberger equation; we show, in particular, that the maximum triplet supercurrent that can pass across the barrier will depend non-monotonically on the thicknesses of the HM layers if the HM and F layers are magnetically exchange coupled at their interface.

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