Controlling superconducting spin flow with spin-flip immunity using a single homogeneous ferromagnet.
Controlling superconducting spin flow with spin-flip immunity using a single homogeneous ferromagnet.
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DOI：
10.1038/srep23926
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发表时间：
2016-04-05
影响因子：
4.6
通讯作者：
Linder J
中科院分区：
文献类型：
--
作者：
Jacobsen SH;Kulagina I;Linder J
通过电子的自旋输运通常受到焦耳加热和由于自旋翻转散射而导致的短衰变长度的困扰。众所周知，当使用传统的超导接触时，可以产生无耗散的自旋电流，但这仅在使用复杂的磁不均匀多层膜时，或在极端情况下，如具有界面磁无序的半金属时，才被实验证明。此外，在自旋翻转散射的存在下，这种自旋超电流如何衰减也是未知的。在这里，我们提出了一种方法，用于产生一个自旋超电流，只用一个单一的均匀的磁性元件。值得注意的是，以这种方式产生的自旋超电流不会在空间上衰减，与仅在自旋弛豫长度内保持极化的正常自旋电流形成鲜明对比。我们还暴露了超导介导的扭矩的存在，即使没有磁不均匀性，表明自旋超电流极化的不同组件从根本上不同的超导相位差的变化。这建立了一种分别调节无耗散自旋和电荷流的机制，并证实了超导体在自旋电子学中的优势。
Spin transport via electrons is typically plagued by Joule heating and short decay lengths due to spin-flip scattering. It is known that dissipationless spin currents can arise when using conventional superconducting contacts, yet this has only been experimentally demonstrated when using intricate magnetically inhomogeneous multilayers, or in extreme cases such as half-metals with interfacial magnetic disorder. Moreover, it is unknown how such spin supercurrents decay in the presence of spin-flip scattering. Here, we present a method for generating a spin supercurrent by using only a single homogeneous magnetic element. Remarkably, the spin supercurrent generated in this way does not decay spatially, in stark contrast to normal spin currents that remain polarized only up to the spin relaxation length. We also expose the existence of a superconductivity-mediated torque even without magnetic inhomogeneities, showing that the different components of the spin supercurrent polarization respond fundamentally differently to a change in the superconducting phase difference. This establishes a mechanism for tuning dissipationless spin and charge flow separately, and confirms the advantage that superconductors can offer in spintronics.