Optically induced non-equilibrium spin transport in mesoscopic semiconductor circuits

应系统地表征和探索介观半导体电路，以便能够基于此类电路中的电子自旋自由度进行有效的信息处理。为此，一种空间分辨的、自旋极化的光电流映射技术将被应用于定义在二维GaAs基异质结电子储库中的介观电路。利用量子点接触(QPC)的自旋分裂一维子带的光电自旋探测器将对自旋极化的光电流进行局部分析。因此，应在弹道和扩散区探索非平衡自旋布居的介观自旋输运现象。特别强调在从二维自旋系统到一维自旋系统的转变过程中的自旋散射过程。此外，我们还期待着对自旋-轨道耦合项引起的自旋弛豫机制的深入了解，即由于结构和体反转不对称。拟议的实验将为介观光电自旋装置奠定基础。在SPP中，我们进一步计划将我们的共焦光电表征方案转移到InAs基和ZnO基电路上，以探索这些材料中的自旋极化光电流特性。

Mesoscopic semiconductor circuits shall be systematically characterized and explored to enable an efficient information processing based upon the electronic spin degree of freedom in such circuits. To this end, a spatially resolved, spin-polarized photocurrent mapping technique shall be applied to mesoscopic circuits defined in two-dimensional electron reservoirs of GaAs-based heterostructures. The spin-polarized photocurrents will be locally analyzed by an optoelectronic spin detector exploiting spin-split one-dimensional subbands of a quantum point contact (QPC). Hereby, mesoscopic spin-transport phenomena of a non-equilibrium spin population shall be explored in the ballistic and diffusive regime. Particular emphasize will be placed on spin scattering processes at the transition from a two-dimensional to a one-dimensional spin system. We furthermore expect insights into spin relaxation mechanisms induced by spin-orbit coupling terms, i.e. due to structural and bulk inversion asymmetry. The proposed experiments shall prepare ground for mesoscopic optoelectronic spin devices. Within the SPP, we further plan to transfer our confocal optoelectronic characterization scheme towards InAs-based and ZnO-based circuits in order to explore the spin-polarized photocurrent properties in these materials as well.