Spin-Transport and Dynamics of Excitons in Magnetic Quantum Heterostructures

w：\awards\awards96\num.doc 9705443 Smith：这是一个更新项目，旨在研究稀释磁性半导体中自旋系统的动力学和输运。 这项研究的主要目标是： （一） 测量激子磁极化子的自旋输运 使用 空间上- 和 时间分辨光致发光光谱学。 （二） 使用时间分辨 近场 光学显微镜以测量ZnMnSe合金内Mn杂质的局部波动和簇。 （三） 测量自旋极化激子布居的动力学以及声子、磁性离子交换、电子空穴交换和能带混合对热化时间的影响。 这项研究将使用特别适合于半导体的全光学技术直接探测自旋相互作用的物理学。 在这些系统中获得的自旋动力学信息也将应用于其他自旋系统，特别是金属系统。 这是一个更新项目，旨在了解掺杂磁性杂质的新型半导体中磁相互作用的基本物理。 对这些相互作用的研究直接适用于磁技术的重要技术领域，如磁存储器（例如，硬盘），超灵敏的磁探测器和磁光调制器。这些新的磁性半导体可以用飞秒激光超快光学方法探测。 这使得人们能够在时间尺度上探测这些磁相互作用的动力学，这在金属系统中是不可能做到的。 这些信息对于改进现有的磁性技术和开发新的磁性技术至关重要。 ***

w:\awards\awards96\num.doc 9705443 Smith : This is a renewal project directed to the study of the dynamics and transport of spin systems in diluted magnetic semiconductors. The main goals of this research are: (1) To measure the spin transport of exciton magnetic polarons using spatially- and temporally-resolved photoluminescence spectroscopy. (2) Use time-resolved near-field optical microscopy to measure local fluctuations and clusters of Mn-impurities within the ZnMnSe alloy. (3) Measure the dynamics of spin-polarized exciton populations and the effect of phonons, magnetic ion exchange, electron-hole exchange and band mixing on the thermalization times. This research will probe directly the physics of spin interactions using all-optical techniques which are particularly suitable for use in semiconductors. The information gained on spin dynamics in these systems will have application to other spin systems as well, particularly in metallic systems. %%% This is a renewal project targeted towards understanding the fundamental physics of magnetic interactions in novel semiconductors which have been doped with magnetic impurities. Study of these interactions has direct applicability to the technologically important area of magnetic technologies such as magnetic memories (eg. Hard disks), super- sensitive magnetic detectors, and magneto-optical modulators. These novel magnetic semiconductors can be probed with ultrafast optical methods using femtosecond lasers. This allows one to probe the dynamics of these magnetic interactions on a time scale which is impossible to do in the metallic systems. Such information is crucial to the improvement of existing and the development of new magnetic technologies. ***