Investigating Two-Dimensional Systems and Surface States Under the Influence of an Internal Exchange Field and Spin-Filtering

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****Technical ABstract****This experimental project aims at investigating two-dimensional systems and surface states such as in topological insulators (TI) and graphene under the influence of an internal exchange field and spin filtering. This investigation is about ferromagnetic order in these Dirac electron systems utilizing the proximity-induced ferromagnetism by magnetic insulator thin film and multilayer stacks, with tailored interfaces. It is theoretically predicted that the spin sub-bands are split and would dramatically alter the spin transport that can be controlled by an electric field. The charge and spin transport behavior in such systems will be studied. This project will also seek Majorana fermions, theoretically predicted to exist in exchange split surface state of p + ip superconducting layer with a strong spin-orbit coupling: nanoscale structures of these, needed, will be investigated. In addition to the rich physics, it is believed that these studies could serve as building blocks towards important future quantum information technologies. Students at all levels (including HS students) and postdocs will participate in this cutting-edge fundamental physics research. They will learn state-of-the-art interfacial characterization techniques at the nanoscale including at the national labs, as well as nanotechnology.****Non-Technical Abstract****This project investigates two dimensional novel quantum systems to bring about not only scientific advancement, but also for their potential in future quantum information technologies. The two newly discovered materials systems (graphene and topological insulators) obeying relativistic quantum mechanics have extraordinary properties, and even more so when magnetism is introduced in them. This project will investigate the electrical and magnetic behavior in the latter case, theoretically predicted to show profound change of properties opening up new quantum areas of physics to explore. When this is verified experimentally, as planned in this project, it is expected to serve as building blocks towards important future energy efficient and economically viable quantum devices such as nonvolatile spin based memory and logic devices. Materials characterization tools, including those at the national facilities will be advancing their capabilities. There will be scientific collaboration both within USA and abroad. Students (including high school students) and postdocs participate in this experimental project. They will be trained in the state-of-the-art science at nanoscale including at the national labs, building the future scientific base for advanced science and technology in USA.