Self-Consistent Model of Spin Transfer Switching of Magnetic Multilayers

The magnetization dynamics in a magnetic memory device has been analyzed self-consistently which takes into consideration the effects of the spin transfer torque. The coupled dynamics of the magnetic moment M and electron spins S are obtained by solving self-consistently the modified Landau-Lifshitz-Gilbert (LLG) equation governing M, and the dynamical equation of S, respectively. These equations incorporate the spin momentum transfer between M and S. The macrospin model is used, which assumes uniform magnetization in the free layer. We performed numerical simulations of the magnetization switching mechanism of M and the accompanying spin dynamics of S. The results indicate that besides the efficiency of the spin transfer torque, other factors such as the anisotropy field and the relaxation speed have a significant effect on the switching mechanism of the M. Our self-consistent model of the coupled magnetization and spin dynamics yields a more refined description of the current-induced switching process, which would be useful in achieving the optimal magnetization switching conditions in device applications.