Optical Control of Electron Spins in Hybrid Quantum Structures of Diluted Magnetic Semiconductors

该研究项目的目标如下：1.设计和制备由II-VI化合物稀磁半导体和磁性金属组成的新型混合纳米结构。2.研究量子点和量子阱混合纳米结构中的光自旋注入和自旋弛豫，用于自旋电子器件。针对上述目标，我们利用分子外延和电子束技术制备了CdTe、CdSe、ZnTe、ZnSe和Mn、Co磁性材料的量子结构和混合纳米结构。光刻。通过施加高磁场，通过飞秒激光光谱研究制造的量子纳米结构。研究了ZnMnSe-ZnSe、CdMnSe-CdSe和CdMnTe-CdTe体系的量子阱和量子点中电子、空穴和激子的自旋注入过程。激子的瞬态光致发光显示了磁场引起的量子结构中的快速自旋注入和自旋弛豫过程。通过瞬态泵浦探针光谱研究了稀磁双量子阱中载流子的超快自旋动力学。电子和空穴的自旋注入动力学在飞秒时域中得到阐明。通过电子束光刻技术制备了稀释磁性半导体和磁性金属的混合纳米结构。混合结构中的稀释磁性量子盘在不施加外部磁场的情况下表现出塞曼分裂，这验证了与量子盘相邻的铁磁纳米级磁体的影响。本研究取得的成果对于自旋电子学应用具有很大的可能性。

The objective of the research program is following:1.Designing and fabrication of new hybrid nanostructures composed of II-VI compound diluted magnetic semiconductors and magnetic metals.2.Study of optical spin injection and spin relaxation in the hybrid nanostructures of quantum dots and quantum wells for the application on spin electronic devices.We have fabricated, for the above objectives, the quantum structures and hybrid nanostructures with CdTe,CdSe,ZnTe,ZnSe and magnetic materials of Mn and Co by using molecular expitaxy and electron beam lithography. Fabricated quantum nanostructures are studied by femtosecond laser spectroscopy by applying high magnetic fields. Spin injection processes of electrons, holes and excitons are investigated in the quantum wells and quantum dots of ZnMnSe-ZnSe,CdMnSe-CdSe and CdMnTe-CdTe systems. Transient photoluminescence of excitons shows fast spin injection and spin relaxation processes in the quantum structures induced by the magnetic field. Ultrafast spin dynamics of carriers is investigated in the diluted magnetic double quantum wells by transient pump-probe spectroscopy. The spin injection dynamics of electrons and holes are clarified in femtosecond time domain. Hybrid nanostructures with the diluted magnetic semiconductors and the magnetic metals were fabricated by electron beam lithography technique. The diluted magnetic quantum disks in the hybrid structures show the Zeeman splitting without applying external magnetic field, which verifies the affection the ferromagnetic nano-scale magnets neighboring to the quantum disks. The obtained results in the present research have high possibilities for spin electronic applications.