Optical Spin Injection and Carrier Transport in Hybrid Nanostructures of Semiconductors and Magnetic Metals

半导体和磁性金属混合纳米结构中的光学自旋注入和载流子传输

• 批准号: 13450002
• 负责人: OKA Yasuo
• 金额: $ 8.83万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13450002/
• 关键词: spin injection; semiconductors; magnetic semiconductors; magnetic materials; spin electronics; nanostructures; lithography; photoluminescence

The objective of the research is following:1.Fabrication of hybrid nanostrctures of quantum wires, quantum dots and quantum wells, which are composed of II-VI compound diluted magnetic semiconductors and magnetic metals.2.Study of optical spin injection and spin transport in the hybrid nanostructures and application for spin electronic devices. For the above objective, we have fabricated the quantum nanostructures and hybrid nanostructures with CdTe, CdSe, ZnTe, ZuSe and magnetic materials of Mn and Co by using molecular expitaxy and electron beam lithography methods. Fabricated quantum and hybrid nanostructures are studied by femtosecond laser spectroscopy in high magnetic fields. Spin injection processes are investigated in CdTe-CdMnTe double quantum wells, where the transient photoluminescence of quantum-well excitons shows that spin injection and spin relaxation processes. Spin switching processes are clarified in ZnTe-ZnMnTe spin superlattices, where the distribution of up-and dow … More n-spin states of excitons is spatially separated in Zute and ZnMnTe layers by the external magnetic fields. The lowest spin state of excitons is modified from that of the ZnTe layer to that of the ZuMnTe due to the large Zeeman splitting of the exciton spins in the ZnMnTe layer. From the transient characteristics of the exciton photoluminescence, the reverse spin injection process (spin switching) is confirmed and the spin injection times are determined. Ultrafast spin dynamics of excitons is investigated in these diluted magnetic nanostructures by transient pump-probe spectroscopy. The spin dynamics in the high density electron-hole plasma, excitons, and Mn ions are clarified in the femotsecond to nanosecond time region. Fabrication of hybrid nanostructures is made by using electron beam lithography technique. The diluted magnetic quantum wells in the hybrid structures are affected by the magnetic field, which is induced by the ferromagnetic Co wires neighboring to the quantum wells. These phenomena have high possibilities for spin electronic applications. Less

研究目的如下：1.制备由II-VI化合物稀磁半导体和磁性金属组成的量子线、量子点和量子阱混合纳米结构。2.混合纳米结构中的光学自旋注入和自旋输运及其在自旋电子器件中的应用研究。为此，我们采用分子外延和电子束光刻方法，以CdTe、CdSe、ZnTe、ZuSe以及Mn、Co磁性材料制备了量子纳米结构和杂化纳米结构。通过高磁场中的飞秒激光光谱研究了制造的量子和混合纳米结构。在 CdTe-CdMnTe 双量子阱中研究了自旋注入过程，其中量子阱激子的瞬态光致发光显示了自旋注入和自旋弛豫过程。自旋转换过程在 ZnTe-ZnMnTe 自旋超晶格中得到阐明，其中激子的上自旋态和道自旋态分布在 Zute 和 ZnMnTe 层中通过外部磁场在空间上分离。由于ZnMnTe层中激子自旋的大塞曼分裂，激子的最低自旋态从ZnTe层的最低自旋态修改为ZuMnTe层的最低自旋态。根据激子光致发光的瞬态特性，确定了反向自旋注入过程（自旋切换）并确定了自旋注入时间。通过瞬态泵浦探针光谱研究了这些稀释的磁性纳米结构中激子的超快自旋动力学。高密度电子空穴等离子体、激子和锰离子中的自旋动力学在飞秒到纳秒时间范围内得到阐明。混合纳米结构的制造是通过使用电子束光刻技术来制造的。混合结构中的稀释磁量子阱受到磁场的影响，该磁场是由与量子阱相邻的铁磁Co线感应的。这些现象对于自旋电子应用具有很大的可能性。较少的

项目成果

S.Shirotori: "Magnetic-field-induced level crossing and the spin dynamics of excitons in Zn_<1-x>Mn_xTe/ZnTe quantum wells"J.Superconductivity, incorporating Novel Magnetism. 16. 457-460 (2003)

S.Shirotori：“磁场诱导的能级交叉和 Zn_<1-x>Mn_xTe/ZnTe 量子阱中激子的自旋动力学”J.超导，结合了新磁性。

H.Sakurai, K.Seo, Z.H.Chen, K.Kayanuma, T.Tomita, A.Murayama, Y.Oka: "Ultrafast exciton spin dynamics in Cd_<1-x>Mn_xTe quantum wells studied by transient pump-probe spectroscopy"Phys.Stat.Sol.(c). 241. 981-984 (2004)

H.Sakurai、K.Seo、Z.H.Chen、K.Kayanuma、T.Tomita、A.Murayama、Y.Oka：“通过瞬态泵浦探针光谱研究 Cd_<1-x>Mn_xTe 量子阱中的超快激子自旋动力学”

M.Nogaku, J.X.Shen, R.Pittini, T.Sato, Y.Oka: "transient-Level Crossing of Free and Bound Excitonic Magnetic Polarons in Cd_<1-x>Mn_xTe Single Crystals"Physical Review B. 63. 153314-1-153314-4 (2001)

M.Nogaku、J.X.Shen、R.Pittini、T.Sato、Y.Oka：“Cd_<1-x>Mn_xTe 单晶中自由和束缚激子磁极化子的瞬态能级交叉”物理评论 B.63.153314-

S.Shirotori: "Magnetic-field-induced level crossing end the spin dynamics of excitons in Zn_<1-x>Mn_xTe/ZnTe quantum wells"J. Superconductivity, incorporating Novel Magnetism. 16. 457-460 (2003)

S.Shirotori：“磁场诱导的能级交叉终止了 Zn_<1-x>Mn_xTe/ZnTe 量子阱中激子的自旋动力学”J。

Y.Oka, K.Kayanuma, S.Shirotori, A.Murayama, I.Souma, Z.H.Chen: "Excitonic Properties and Dynamics in Diluted Magnetic Semiconductor Quantum Nanostructures"Nonlinear Optics. 29. 491-499 (2002)

Y.Oka、K.Kayanuma、S.Shirotori、A.Murayama、I.Souma、Z.H.Chen：“稀磁半导体量子纳米结构中的激子性质和动力学”非线性光学。