High frequency magnetization rotation induced by a dc spin-polarized current in magnetic nanostructures

While most recent studies of the spin-transfer torque effect in nanoscale magnetic structures mainly concern with spin-wave excitation and the magnetization hysteretic switching induced by spin-polarized current, we theoretically investigate the large angle magnetization precessions triggered and sustained by the spin current in great detail using the Landau-Lifshitz-Gilbert equation. The study is conducted particularly on the nanostructures comprising square magnets with an easy-plane anisotropy. A simple nanoscale magnetoelectronic device is proposed based on the structure without mechanical components to function as a motor to convert a dc current into an ac voltage of microwave frequency. The device is unique because the output amplitude and frequency can be continuously tuned by the electrical current in a wide range. Quantitative analysis of the device structure, function, and realization is provided. (C) 2004 American Institute of Physics.