Numerical study of spin-torque oscillators with perpendicular-to-plane polarizer by using a Heuristic method

We searched solutions of the Landau-Lifshitz-Gilbert-Slonczewski equation of micromagnetism by using the Simulated Annealing algorithm. The solutions were expressed as a composition of perpendicular harmonic oscillations. For a spin-torque oscillator with perpendicular-to-plane polarizer and in-plane magnetization free layer, both stable states and steady state oscillations of the free layer magnetization were obtained. A linear variation of the frequency oscillation with the current density was obtained. The approach presented is useful in exploring the behaviour of a spin-torque oscillator without imposing initial conditions for the free layer magnetization.