A novel theoretical approach to magnetization dynamics driven by spin-polarized currents is presented. Complete stability diagrams are obtained for the case where spin torques and external magnetic fields are simultaneously present. Quantitative predictions are made for the critical currents and fields inducing magnetization switching, for the amplitude and frequency of magnetization self-oscillations, and for the conditions leading to hysteretic transitions between self-oscillations and stationary states.

Methods of nonlinear-dynamical-system theory are applied to the study of magnetization dynamics under the action of microwave magnetic fields. In the case of a system with uniaxial anisotropy subject to a circularly-polarized microwave field, the conditions are derived under which the magnetization reversal field is substantially reduced by the application of the microwave field. The dependence of magnetization switching on microwave-field-pulse duration is discussed and analytical expressions are derived for the minimum pulse duration leading to switching. (c) 2009 American Institute of Physic

We present a quantitative, systematic study of the effect of magnetostriction on the dynamical properties in NiFe alloys. Both the ferromagnetic resonance frequency and the damping times are correlated to the magnetostriction. In addition, we find that the Gilbert damping parameter varies by more than 100% over the range of Ni percentage tested (61.9%–86.7%).