Collective electronic excitations in two-dimensional systems with spin-orbit interaction

本计画将利用拉曼散射研究二维电子系统中自旋-轨道相互作用的集体效应。为此，将对具有不同生长方向并因此具有不同自旋轨道场对称性的调制掺杂GaAs-AlGaAs量子威尔斯阱进行实验。在实验中，为了打破时间反演对称性，将波矢量转移到电子激发，以及在不同配置中应用外部磁场。子带内以及子带间的自旋密度激发将进行调查。其目的是定量确定集体自旋轨道场，这是固有的相干自旋激发。通过将实验确定的自旋轨道场与单粒子图像中的考虑进行比较，将探索集体效应的作用。此外，自旋库仑阻力对相干自旋激发的影响将被研究。我们期望从该项目中获得对自旋轨道相互作用中集体现象的作用的有价值的见解。

In this project, the role of collective effects concerning spin-orbit interaction in two-dimensional electron systems shall be investigated by means of Raman scattering. To this end, experiments on modulation-doped GaAs-AlGaAs quantum wells with different growth directions and, hence, different symmetries of the spin-orbit fields, shall be performed. In the experiments, a wave-vector transfer to the electronic excitations in order to breaking time-reversal symmetry, shall be possible as well as the application of external magnetic fields in different configurations. Intrasubband as well as intersubband spin-density excitations shall be investigated. The aim is the quantitative determination of the collective spin-orbit fields, which are inherent to coherent spin excitations. Via the comparison of the experimentally determined spin-orbit fields with considerations in a single-particle picture, the role of collective effects shall be explored. Furthermore, the influence of spin Coulomb drag on coherent spin excitations shall be investigated. We expect from the project valuable insights into the role of collective phenomena in spin-orbit interaction.