CAREER: Ultrafast Magnetism in Complex Materials: Coherent and Cooperative Phenomena

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*** Non-technical ***One major challenge now being posed for fundamental science and technology is to detect, understand and control spins-an ensemble of nanomagnets-in complex systems within one hundred quadrillionth of a second. On one hand, the complex structures made of inter-connected, individual nano-magnetic building blocks can exhibit valuable characteristics and improved functionalities, which are fundamentally different from the sum of their components. On the other hand, such dynamic magnetic processes are at least 1000 times faster than those of the traditional thermal-magnetic processes used thus far, and thereby carry great promise to exceed the upper limit of the magnetic switching speed (0.1-10 GHz) in modern magneto-optical recording industry and enable extremely high-speed magnetic storage/logic devices. This proposal has identified some major opportunities to address these problems via exploiting ultrashort flashes of mid-infrared and far-infrared (trillion cycles per second) electromagnetic radiation. Success in this "ultrafast spin challenge" will reveal as-yet-undiscovered dynamic processes in advanced magnetic systems, and offer ultimate solution towards the problems indentified. The proposal consists of interconnected, specific plans for education and outreach that span high school teachers and their students, undergraduate and graduate level student training; seeks to attract and keep talented students in careers in sciences, and mentor them along their journey to success; develop new courses with complementary hands-on laboratory modules emphasizing ultrafast laser technology, coupled to undergraduate and graduate curriculum.*** Technical ***This proposal explores ultrafast magnetic phenomena in nanoscale and complex magnetic systems using dynamic magneto-optical spectroscopic methods exploiting femtosecond laser excitations. One of the most challenging questions in condensed matter physics and materials science today is whether one can detect, understand and control macroscopic magnetic orders in their highly non-equilibrium, non-thermal states at femtosecond time scales. Such processes are at least 1000 times faster than those of the traditional thermal-magnetic processes used thus far, and thereby carry great promise to exceed the upper limit of the magnetic switching speed (0.1-10 GHz) in modern magneto-optical recording industry and enable extremely high-speed magnetic storage/logic devices. However, thus far how photoexcited coherence and/or non-thermal carriers can substantially modify the macroscopic ordering at such time scales has been poorly addressed to date and most of the predicted exotic properties of photo-driven magnetic systems have yet to be observed. This proposal will explore photoinduced non-thermal, fs magnetic phase transition and significantly advance our knowledge of quantum spin systems driven far from the equilibrium. The proposal consists of interconnected, specific plans for education and outreach that span high school teachers and their students, undergraduate and graduate level student training; develop new courses with complementary hands-on laboratory modules emphasizing ultrafast laser technology.