Application of self-organization methods to current-induced magnetization dynamics of a single-domain ferromagnet

Magnetization dynamics of a single-domain ferromagnet is studied theoretically using the methods developed for self-organization phenomena. Time evolution of the magnetization is described by the Landau-Lifshitz-Gilbert equation with the spin-transfer torque included. The equilibrium and stationary states are investigated as a function of spin current and external magnetic field. The presented bifurcation diagram allows the margins of a neutral stability mode of the equilibrium and stationary states to be determined. An envelope equation for the magnetization switching is derived. The switching time Delta tau between different states is found to be comparable to the half-width of the time derivative of the system energy, which allows the energy flow due to spin current and the magnetization switching velocity to be related. Dynamics of the phase states in external magnetic field and in the presence of spin current is analyzed using different methods of numerical analysis. (c) 2007 American Institute of Physics.