论文标题
GAA中光学取向的实时建模：自旋极化程度的产生和衰减
Real-time modelling of Optical orientation in GaAs: generation and decay of the degree of spin polarization
论文作者
论文摘要
由于与超短圆极化激光源的耦合，我们提供了散装GAA的光学取向的实时ABINITIO描述。正确再现了传统带中自旋极化电子的注入，并平行于激光（$ \ Mathbf {p} $）与激光传播方向平行。讨论了$ \ Mathbf {p}（t）$的生成和演变的详细分析。单个$ \ mathbf {k} $ - 点动力学是围绕固定轴的动作，该轴具有常数$ | \ Mathbf {p} | $和固定频率。取而代之的是，$ \ mathbf {k} $ - 集成信号仅显示一个依赖时间的$ p_z（t）$，并且由于变质而导致激光泵结束后几秒钟衰减几秒钟。由于泵激活的个体贡献会导致破坏性干扰，因此会发生变色。我们根据几年前提出的\ emph {自由归纳衰减}机制来解释结果。我们第一次能够以完整的Abinitio方式复制这种效果，从而定量估计相关的衰减时间。我们的结果还显示了在许多实时Abinitio模拟中观察到的自旋磁化时间衰减的可能解释。
We present a real-time abinitio description of optical orientation in bulk GaAs due to the coupling with an ultrashort circular polarized laser source. The injection of spin polarized electrons in the conduction band is correctly reproduced, and a non vanishing spin polarization ($\mathbf{P}$) parallel to the direction of propagation of the laser ($z$) emerges. A detailed analysis of the generation and the evolution of $\mathbf{P}(t)$ is discussed. The single $\mathbf{k}$-point dynamics is a motion of precession around a fixed axis with constant $|\mathbf{P}|$ and fixed frequency. Instead, the $\mathbf{k}$-integrated signal shows only a time dependent $P_z(t)$ and decays few pico seconds after the end of the laser pump due to decoherence. Decoherence emerges since the individual contributions activated by the pump give rise to destructive interference. We interpret the results in terms of the \emph{free induction decay} mechanism proposed some years ago. For the first time we are able to reproduce such effect in a full abinitio fashion, giving a quantitative estimate of the associated decay time. Our result also shows a possible explanation to the time decay of spin magnetization observed in many real-time abinitio simulations.
