Topological spin transport by Brownian diffusion of domain walls
Topological spin transport by Brownian diffusion of domain walls
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畴壁布朗扩散的拓扑自旋输运
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
Y. Tserkovnyak
中科院分区：
文献类型：
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作者：
Se Kwon Kim;S. Takei;Y. Tserkovnyak
我们提出了在简单平面铁磁绝缘体中的热填充磁区壁(DWS)作为两个金属之间的强健的自旋载流子。DW的手性作为拓扑电荷，通过自旋转移扭矩与金属自旋积累耦合，导致DW在界面上的热成核速率与手性有关。在特定(净)手性的超额布居DW扩散并离开另一界面的铁磁体后，它们通过自旋泵浦重新发射自旋电流。拓扑荷的守恒支持自旋输运随着铁磁体长度的增加而代数衰减；这类似于超流体自旋输运的衰减行为，但与磁振子自旋输运的指数衰减相反。我们设想，在具有奇异自旋相的材料中，通过利用拓扑特征及其相关的激发守恒量，可以实现具有代数衰变的类似的自旋输运。
We propose thermally-populated domain walls (DWs) in an easy-plane ferromagnetic insulator as robust spin carriers between two metals. The chirality of a DW, which serves as a topological charge, couples to the metal spin accumulation via spin-transfer torque and results in the chirality-dependent thermal nucleation rates of DWs at the interface. After overpopulated DWs of a particular (net) chirality diffuse and leave the ferromagnet at the other interface, they reemit the spin current by spin pumping. The conservation of the topological charge supports an algebraic decay of spin transport as the length of the ferromagnet increases; this is analogous to the decaying behavior of superfluid spin transport but contrasts with the exponential decay of magnon spin transport. We envision that similar spin transport with algebraic decay may be implemented in materials with exotic spin phases by exploiting topological characteristics and the associated conserved quantities of their excitations.