We have studied the spin dynamics of a high-mobility two-dimensional electron system in a GaAs/Al_{0.3}Ga_{0.7}As single quantum well by time-resolved Faraday rotation and time-resolved Kerr rotation in dependence on the initial degree of spin polarization, P, of the electrons. By increasing the initial spin polarization from the low-P regime to a significant P of several percent, we find that the spin dephasing time, $T_2^\ast$, increases from about 20 ps to 200 ps; Moreover, $T_2^\ast$ increases with temperature at small spin polarization but decreases with temperature at large spin polarization. All these features are in good agreement with theoretical predictions by Weng and Wu [Phys. Rev. B {\bf 68}, 075312 (2003)]. Measurements as a function of spin polarization at fixed electron density are performed to further confirm the theory. A fully microscopic calculation is performed by setting up and numerically solving the kinetic spin Bloch equations, including the D'yakonov-Perel' and the Bir-Aronov-Pikus mechanisms, with {\em all} the scattering explicitly included. We reproduce all principal features of the experiments, i.e., a dramatic decrease of spin dephasing with increasing $P$ and the temperature dependences at different spin polarizations.
Detection of large magneto-anisotropy of electron spin dephasing in a high-mobility two-dimensional electron system in a $[001]$ GaAs/AlGaAs quantum well
Linear polarization dependence of microwave-induced magnetoresistance oscillations in high-mobility two-dimensional systems
我们研究了改变入射微波的线性偏振角$θ$相对于直流电流辐射诱导的磁阻振荡在一个二维（2D）系统内的平衡方程制定的光子辅助磁输运模型，考虑辐射衰减作为唯一的阻尼机制的效果。在极值处，振荡磁阻$R_{xx}$的幅度随着极化角$θ$的旋转而呈现高达5倍的正弦幅度变化。最大振幅通常出现在非零$θ$处，这取决于所讨论的极值、2D电子设置、辐射频率和磁场方向。这些结果为Mani { \it et al.}的实验观察提供了一个自然的解释。[Phys. Rev. B { \bf 84}，085308（2011）]和Ramanayaka { \it et al.} [Phys. Rev. B { \bf 85}，205315（2012）]。
Disorder Enhanced Spin Polarization in Diluted Magnetic Semiconductors
我们提出了一个稀磁半导体的理论研究，其中包括一个现实的主机能带结构内的自旋轨道耦合，并明确治疗由于随机取代Mn离子的无序的影响。自旋-轨道耦合通过混合价带中不同的自旋态降低了自旋极化，而Mn离子的无序增强了自旋极化，这是由于铁磁杂质团簇和杂质束缚态的形成。无序导致对形成杂质带以及与价带杂化的空穴载流子的大的影响。对于Mn掺杂0.01 < x < 0.04，系统是具有大有效质量和低迁移率的金属。
Electrostatic gate-controlled quantum interference in a high-mobility two-dimensional electron gas at the (La$_{0.3}$Sr$_{0.7}$)(Al$_{0.65}$Ta$_{0.35}$)O$_3$/SrTiO$_3$ interface
National High Magnetic Field Laboratory, Los Alamos National Laboratory（美国国家强磁场实验室）；Department of Physics, National University of Singapore（新加坡国立大学物理系）；Laboratoire National des Champs Magnétiques Intenses (LNCMI-EMFL), Université de Toulouse, CNRS, INSA, UPS（法国图卢兹大学国家强磁场实验室）
Anisotropic magnetotransport of electron gases at SrTiO3 (111) and (110) surfaces with high mobility
用Ar+辐照在SrTiO_3（001）、（110）和（111）取向的表面上产生了电子气，（001）、（110）和（111）取向的表面具有完全的金属行为，低温迁移率分别高达5500 cm ~ 2 V ~（-1）s ~（-1）、1300 cm ~ 2 V ~（-1）s ~（-1）和8600 cm ~ 2 V ~（-1）s ~（-1）。研究了电流沿不同晶轴方向施加时样品的面内各向异性磁电阻（AMR），以消除洛伦兹力效应。AMR显示出与晶轴的固定取向一致的特征，对于（001）-、（110）和（111）-表面分别具有4倍、2倍和近6倍对称性，与电流方向无关。这些特征可能是由二维费米面的自旋轨道织构极化引起的。此外，还观察到了（111）面的6- 2重对称破缺.我们的结果表明二维电子结构的对称性对电子气在STO表面的输运行为的影响。
