Optical and Electrical Control of Magnetism and Magneto-Optical Response in Semiconductor Nanoparticles and Nanoparticle Devices

应用科学和工程中的一个关键挑战是在室温下实现具有电、磁和光功能的材料和器件。该项目的中心目标是对胶体、磁性掺杂半导体(量子点、纳米团簇、纳米带)的磁光性质有一个基本的了解，并最终开发出实现磁和磁光功能的电气和光学控制的方案。因此，我们从我们的主要合作伙伴，首尔大学的Hyeon教授和华盛顿大学的Gamelin教授制备的全球独特的纳米材料中受益。主要的科学目标可以分为两个密切相关的子目标。第一个子目标是通过载流子诱导的过渡金属掺杂的自旋排列修饰来展示电控磁光功能。为此，磁性掺杂纳米晶体将被纳入器件方案，允许电子或空穴，或两者兼而有之。例如，这使得能够分别识别电子和空穴与磁性掺杂剂之间的相互作用。第二个子目标是从我们最近关于数字掺杂纳米团簇和量子点的结果发展而来的。因此，半导体掺杂的终极极限将通过研究掺杂原子数量受控到一个水平的单一纳米晶体来解决。这指向了新发展的孤子学研究领域，在这个领域中，单掺杂原子控制着功能。与我们的项目合作伙伴一起，我们打算通过替代结构(核壳设计、魔术大小的团簇)和新型掺杂剂(除锰之外的钴、铜)来扩展稀磁半导体纳米材料家族，包括与例如银的共掺杂，以故意增加额外的电荷载流子。我们预计，与外延生长的纳米材料相比，这些形状和尺寸的工程纳米材料中强烈的量子和介电限制将大大增加交换效应的能量尺度(大约一个到两个数量级)，为实现室温功能铺平道路。

One key challenge in applied science and engineering is the realization of materials and devices with combined electrical, magnetic and optical functionality at room temperature. The central goal of the project is to work out a fundamental understanding of the magnetooptical properties in colloidal, magnetically doped semiconductors (quantum dots, nanocluster, nano ribbons) and finally to develop schemes for achieving electrical and optical control of magnetism and magnetooptical functionality. Hereby, we profit from the worldwide unique nanomaterials prepared by our key partners, Prof. Hyeon, U Seoul, and Prof. Gamelin, U Washington. The main scientific objectives can be divided into two closely connected subgoals. The first sub-goal is to demonstrate electrically controlled magneto-optical functionality via carrier-induced modification of the spin alignment of transition metal dopants. For that purpose, magnetically doped nanocrystals will be incorporated into device schemes allowing electrical injection of either electrons or holes, or both. This, e.g., enables a separate identification of the interaction between electrons and holes, respectively, with magnetic dopants. The second sub-goal developed from our recent results on digitally doped nanoclusters and quantum dots. Hereby, the ultimate limit of semiconductor doping will be addressed by investigating single nanocrystals doped with a controlled number of doping atoms down to the level of one. This points towards the newly developed research field of solotronics, where single doping atoms control functionality. Together with our project partners we intend to extend the dilute magnetic semiconductor nanomaterial family by alternative architectures (core-shell design, magic-sized cluster) and novel dopants (Co, Cu, in addition to Mn), including co-doping with, e.g. Ag, for adding additional charge carriers on purpose. We expect that the strong quantum and dielectric confinement in these shape and size engineered nanomaterials increase the energy scale of exchange effects largely (about one to two orders of magnitude) with respect to their epitaxially grown counterparts, paving the way to room temperature functionality.