Magnetization oscillation in a nanomagnet driven by a self-controlled spin-polarized current: Nonlinear stability analysis

The magnetization dynamics of a nanomagnet is investigated by performing macromagnetic simulation and nonlinear stability analysis on the spin precession trajectory. We propose a scheme in which a self-controlled spin-polarized current plus a magnetic field is employed to excite the self-oscillation of the magnetization through spin precession. It is revealed that the negative feedback mechanism of the spin torque is responsible for the self-oscillation excitation. The periodic solutions and the limit cycle stability for two specific configurations in terms of the directions of the spin-polarized current and magnetic field are analyzed, implying that the self-oscillation of magnetization essentially depends on the demagnetization field.