Hikino S, Yunoki S
Computational Condensed Matter Physics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan and CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan.
Computational Condensed Matter Physics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan and CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan and Computational Materials Science Research Team, RIKEN AICS, Kobe, Hyogo 650-0047, Japan and Computational Quantum Matter Research Team, RIKEN CEMS, Wako, Saitama 351-0198, Japan.
Phys Rev Lett. 2013 Jun 7;110(23):237003. doi: 10.1103/PhysRevLett.110.237003.
We theoretically study spin current through ferromagnet (F) in a Josephson junction composed of s-wave superconductors and two layers of ferromagnets. Using quasiclassical theory, we show that the long-range spin current can be driven by the superconducting phase difference without a voltage drop. The origin of this spin current is due to spin-triplet Cooper pairs (STCs) formed by electrons of equal spin, which are induced by the proximity effect inside the F. We find that the spin current carried by the STCs exhibits long-range propagation in the F even where the Josephson charge current is practically zero. We also show that this spin current persists over a remarkably longer distance than the ordinary spin current carried by spin polarized conduction electrons in the F. Our results thus indicate the promising potential of Josephson junctions based on multilayer ferromagnets for spintronics applications with long-range propagating spin current.
我们从理论上研究了由s波超导体和两层铁磁体组成的约瑟夫森结中通过铁磁体（F）的自旋电流。利用准经典理论，我们表明长程自旋电流可以由超导相位差驱动而无电压降。这种自旋电流的起源是由于等自旋电子形成的自旋三重态库珀对（STCs），它们是由F内部的近邻效应诱导产生的。我们发现，即使约瑟夫森电荷电流实际上为零，STCs携带的自旋电流在F中仍表现出长程传播。我们还表明，这种自旋电流比F中自旋极化传导电子携带的普通自旋电流持续传播的距离长得多。因此，我们的结果表明基于多层铁磁体的约瑟夫森结在具有长程传播自旋电流的自旋电子学应用中具有广阔的前景。
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