| We studied current-induced magnetization dynamics in Co/Cu/Co nanopillar with in-plane magnetization traversed by a perpendicular-to-plane spin-polarized current and magnetic fields through simulation. The Landau-Lifshitz-Gilbert (LLG) equation incorporating the spin transfer torque ( STT ) effect was employed to model the magnetization dynamics for a nanoscale pillar structure under the influence of spin-polarized current and magnetic field perpendicular to the sample plane. We investigate the dynamics of magnetization by solving modified LLG equation numerically using Gauss-Seidel projection method.The magnetization dynamics can be grouped into six types. They are unchanging state, precessional state,sub-precessional state,instability state,multi-domain state,bistable state respectively.In unchanging state,the magnetizations were kept at their initial stable alignment.In the steady precessional state,the magnetizations precession frequency is constant and can be altered by the perpendicular-field.In sub-precessional state,the magnetizations precession frequency remains a constant, but we find a staggering stack of primary and secondary wave.And we studied the magnetic field changes in the value of the steady precessional and sub-precessional state.In instability state, the free layer remain in signal-domain but the magnetizations precession frequency becomes variables.In multi-domain state,the free layer becomes multi-domain and each domain magnetization precession around effective field.When the current is large enough,the magnetization can be switched back and forth between stable parallel and antiparallel alignment. In this state there are two types of magnetization switching mode:At relatively lower dc current density, the magnetizations were switched step by step through domain wall migration.At relatively higher dc current density,the magnetizations were kept almost as a signal domain during the switching time .
|
PDF Full Text Request