Spin drift and diffusion in one-and two-subband helical systems
Spin drift and diffusion in one-and two-subband helical systems
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DOI：
10.1103/physrevb.95.125119
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发表时间：
2017-03-14
影响因子：
3.7
通讯作者：
Salis, Gian
中科院分区：
文献类型：
--
作者：
Ferreira, Gerson J.;Hernandez, Felix G. G.;Salis, Gian
本文采用Rashba模型、线性Dresselhaus模型和立方Dresselhaus模型以及子带间自旋-轨道耦合模型，发展了二维电子气中自旋漂移和扩散的理论。额外的子带自由度引入了新的特性的持续自旋螺旋（PSH）动力学。如前所述，对于可忽略的子带间散射率，独立子带的磁化强度之和导致具有长自旋寿命的交叉PSH的棋盘图案。对于强子带间散射，我们的快速子带动力学模型作为一个新的随机变量，产生一个动力学集的两个子带的平均自旋轨道耦合。在这种情况下，交叉PSH变成各向同性，呈现具有短自旋寿命的圆形（贝塞尔）图案。此外，有限的漂移速度打破了平行和横向方向之间的对称性，扭曲和拖动图案。我们发现，最大自旋寿命移离PSH政权的漂移速度增加。我们提出了这些情况下的近似解析解，并定义其有效域。磁场和初始包展宽的影响进行了讨论。
The theory of spin drift and diffusion in two-dimensional electron gases is developed in terms of a random walk model incorporating Rashba, linear and cubic Dresselhaus, and intersubband spin-orbit couplings. The additional subband degree of freedom introduces new characteristics to the persistent spin helix (PSH) dynamics. As has been described before, for negligible intersubband scattering rates, the sum of the magnetization of independent subbands leads to a checkerboard pattern of crossed PSHs with long spin lifetime. For strong intersubband scattering we model the fast subband dynamics as a new random variable, yielding a dynamics set by averaged spin-orbit couplings of both subbands. In this case the crossed PSH becomes isotropic, rendering circular (Bessel) patterns with short spin lifetime. Additionally, a finite drift velocity breaks the symmetry between parallel and transverse directions, distorting and dragging the patterns. We find that the maximum spin lifetime shifts away from the PSH regime with increasing drift velocity. We present approximate analytical solutions for these cases and define their domain of validity. Effects of magnetic fields and initial package broadening are also discussed.