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

本课题将利用拉曼散射的方法研究二维电子系统中自旋轨道相互作用中的集体效应。为此，需要对具有不同生长方向的调制掺杂GaAs-AlGaAs量子阱进行实验，从而获得不同的自旋轨道场对称性。在实验中，为了打破时间反转对称性，可以将波矢量传递到电子激励中，也可以应用不同构型的外磁场。将研究子带内和子带间的自旋密度激发。目的是定量确定共相干自旋激发所固有的集体自旋-轨道场。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，探讨集体效应的作用。此外，还研究了自旋库仑阻力对相干自旋激发的影响。我们期望从这个项目中对集体现象在自旋轨道相互作用中的作用有宝贵的见解。

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.