Micromagnetic computations of spin polarized current-driven magnetization processes

Magnetization reversal by spin polarized current flowing perpendicular to a 10 nm Co/6 nm Cu/2.5 nm Co circular nanopillar of 130 nm diameter is studied by means of a micromagnetic model. The spin transfer torque is included as an additional term in the Gilbert equation following the theoretical calculations of Slonczewski. The Ampere field due to the current and the dipolar antiferromagnetic coupling between the Co layers are also taken into account. The simulations reveal a complex switching behavior that involves highly inhomogeneous magnetization configurations with multiple domains. It is also found that the Ampere field plays a crucial role in promoting the switching. In fact, switching would not occur unless this contribution is taken into account.