Stability analysis of magnetization in a perpendicular magnetic layer driven by spin Hall effect

Abstract

We investigate the stability of magnetization in free layer where the spin torque is induced by the spin Hall effect. In terms of the Landau–Liftshitz–Gilbert equation, we find the low-energy and high-energy equilibrium states, as well as the saddle points. The stability region is defined in the phase diagram spanned by the current density and the spin Hall angle. The spin Hall effect makes the previous saddle point into a stable state above a critical current. However, in the presence of magnetic field, the spin Hall effect leads to the opposite changes in the stable regions of the two low-energy states.