Micromagnetic simulations of persistent oscillatory modes excited by spin-polarized current in nanoscale exchange-biased spin valves

Three-dimensional micromagnetic simulations of current-driven magnetization dynamics are performed in nanoscale exchange biased spin vales by considering back action of spin-transfer torque on the pinned layer, nonlinear damping and random thermal torques. The studies have shown that at a nonzero temperature and a subcritical current, the magnetization dynamics has displayed nonstationary behavior in which two independent persistent oscillatory modes are excited.