Unified theory of spin dynamics in a two-dimensional electron gas with arbitrary spin-orbit coupling strength at finite temperature
Unified theory of spin dynamics in a two-dimensional electron gas with arbitrary spin-orbit coupling strength at finite temperature
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有限温度下任意自旋轨道耦合强度二维电子气自旋动力学统一理论
DOI：
10.1103/physrevb.86.174301
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发表时间：
2012
影响因子：
3.7
通讯作者：
J. Sinova
中科院分区：
文献类型：
--
作者：
Xin Liu;J. Sinova
我们研究了有限温度下具有任意自旋轨道耦合 (SOC) 强度和对称性的 III-V 族半导体量子阱中存在杂质和电子-电子 (e-e) 散射的情况下的自旋动力学。我们推导了非弹性散射存在下的耦合自旋电荷动力学方程，并提供了一种新的形式，以统一的方式描述弱和强 SOC 状态下的自旋弛豫和动力学。正如预期的那样，在弱 SOC 状态下，我们的理论再现了之前所有的零温度结果，其中大部分都集中在杂质散射引起的自旋电荷动力学上。在 Rashba 和线性 Dresselhaus SOC 的强度匹配的区域（称为 SU(2) 对称点）中，实验观察到具有较长自旋寿命的自旋螺旋模式，其无法解释的非单调温度依赖性在 75 K 左右达到峰值。作为我们理论的关键测试，我们能够自然地定量解释这种非单调依赖性，并表明它是作为 Dyakonov-Perel 机制之间的竞争而出现的，在 SU(2) 处受到抑制点和 Elliott-Yafet 机制。在强 SOC 体系中，我们证明我们的理论直接再现了弹道体系中 SU(2) 对称点处唯一已知的分析结果。正如我们之前所展示的，它还解释了当电子散射时间大于自旋进动时间的一半时，由于 SOC，阻尼振荡动力学会增加。因此，我们在实验上可获得的完整相图中提供了二维电子气自旋动力学的统一理论。
We study the spin dynamics in the presence of impurity and electron-electron (e-e) scattering in a III-V semiconductor quantum well with arbitrary spin-orbit coupling (SOC) strength and symmetry at finite temperature. We derive the coupled spin-charge dynamic equations in the presence of inelastic scattering and provide a new formalism that describes the spin relaxation and dynamics in both the weak and the strong SOC regimes in a unified way. In the weak SOC regime, as expected, our theory reproduces all previous zero-temperature results, most of which have focused on impurity-scattering induced spin-charge dynamics. In the regime where the strength of the Rashba and linear Dresselhaus SOC match, known as the SU(2) symmetry point, experiments have observed the spin-helix mode with a large spin-lifetime whose unexplained nonmonotonic temperature dependence peaks at around 75 K. As a key test of our theory, we are able to naturally explain quantitatively this nonmonotonic dependence and show that it arises as a competition between the Dyakonov-Perel mechanism, suppressed at the SU(2) point, and the Elliott-Yafet mechanism. In the strong SOC regime, we show that our theory directly reproduces the only previous known analytical result at the SU(2) symmetry point in the ballistic regime. It also explains, as we have shown previously, the rise of damped oscillating dynamics when the electron scattering time is larger than half of the spin precession time due to the SOC. Hence we provide a unified theory of the spin dynamics in two-dimensional electron gases in the full phase diagram experimentally accessible.