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

点击翻译按钮获取中文摘要

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.