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Ultrafast Magnetoelectronic Devices

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Final rept. 1 Oct 2007-30 Sep 2011

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This research project explored new methods to coherently control magnetization dynamics in nanostructures based on a recently discovered strong and short-range quantum mechanical interaction between a spin-current and background magnetization- known as spin-transfer. This was accomplished through the fabrication and study of prototype spin-transfer devices. Specifically, we pursued the following approaches 1 Fabrication of magnetic devices in which the magnetic anisotropy is controlled through oriented, layered or epitaxial film growth 2 Realization of magnetic devices that combine low moment and high moment materials and 3 High speed electrical measurements of magnetization switching and precession. We had a number of significant experimental results that have become benchmarks in the field 1. We demonstrated spin-transfer switching with current pulses shorter than 300 psec. We also studied how the switching threshold depends on current pulse amplitude and duration for pulses between 100 ps and 1 s in duration. 2. We developed an all electrical method to study magnetization relaxation in a nanomagnet with 50 ps time relaxation and used this method to determine the relaxation time of a nanomagnet in a prototype spin-transfer device. 3. We explored highly non-linear magnetization dynamics excited by microwave spin-currents. 4. We also characterized transition metal multilayer and alloy thin films of interest in spin-transfer torque devices using broadband 1-50 GHz ferromagnetic resonance spectroscopy.

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  • Electricity and Magnetism

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