Dynamic spin-Hall effect and driven spin helix for linear spin-orbit interactions
Dynamic spin-Hall effect and driven spin helix for linear spin-orbit interactions
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用于线性自旋轨道相互作用的动态自旋霍尔效应和驱动自旋螺旋
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
D. Loss
中科院分区：
文献类型：
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作者：
M. Duckheim;D. Maslov;D. Loss
我们推导了有限、无序二维半导体通道中电致自旋积累的边界条件。虽然对于直流电场，这些边界条件选择相当于消失的自旋霍尔效应的空间恒定自旋剖面，但我们表明，面内交流电场会导致非零交流自旋霍尔效应，即，即使对于线性本征自旋轨道相互作用，它也会产生空间不均匀的面外极化。分析[001]和[110]生长的量子阱中的不同几何形状，我们发现虽然这种面外极化通常限制在距离通道边缘几个自旋轨道长度内，但也有可能产生延伸到整个通道的空间振荡自旋剖面。后者是由于通道横向上驱动的自旋螺旋模式的激发所致。我们表明，虽然有限的频率抑制了这种模式，但它可以通过调谐到与电场频率共振的磁场来放大。在这种情况下，Rashba 和 Dresselhaus SOI 相同强度下的有限尺寸效应导致这种螺旋模式的幅度增强。我们评论了自旋电流和边界条件之间的关系。
We derive boundary conditions for the electrically induced spin accumulation in a finite, disordered two-dimensional semiconductor channel. While for dc electric fields these boundary conditions select spatially constant spin profiles equivalent to a vanishing spin-Hall effect, we show that an in-plane ac electric field results in a nonzero ac spin-Hall effect, i.e., it generates a spatially nonuniform out-of-plane polarization even for linear intrinsic spin-orbit interactions. Analyzing different geometries in [001]- and [110]-grown quantum wells, we find that although this out-of-plane polarization is typically confined to within a few spin-orbit lengths from the channel edges, it is also possible to generate spatially oscillating spin profiles which extend over the whole channel. The latter is due to the excitation of a driven spin-helix mode in the transverse direction of the channel. We show that while finite frequencies suppress this mode, it can be amplified by a magnetic field tuned to resonance with the frequency of the electric field. In this case, finite-size effects at equal strengths of Rashba and Dresselhaus SOI lead to an enhancement of the magnitude of this helix mode. We comment on the relation between spin currents and boundary conditions.