The Research Of Magnetization Dynamics Under A Spin Polarization Current

In this paper, we have theoretically studied the magnetization dynamics in the magnetic multilayer system by stability analysis. There are three parts to describe the main content.First of all, we introduce the application of spintronics, and spin Hall effect. Secondly, we describe the model of spin transfer torque where the current is perpendicular to plane. Then, we introduce the stability of spin wave and the magnetization dynamics with a field like spin torque. At last, we consider a magnetic multilayers, which consist of a heavy metal layer and a ferromagnetic metal. The dynamics of magnetization in the ferromagnetic layer can be described by Landau-Liftshitz-Gilbert equation. By stability analysis, we solve the solution for the magnetic equilibrium states. In terms of perturbation method we discuss the stability of magnetization equilibrium state. We discuss the magnetic equilibrium states under no external magnetic field or the external magnetic field in the y direction. In the case of no external magnetic field, we have three sets of equilibrium states, and the minimal energy state is the stable state. The maximum energy state is not stable. Under the control of the spin Hall angle and current value, we can obtain the phase diagrams of the stable region. In the case of the external magnetic field in the y direction, we have three sets of equilibrium states. By adjusting jc and the external magnetic filed, we can obtain the phase diagrams of the stable region.