Dynamics of magnetization switching of exchange-coupled trilayers by using a micromagnetic simulation

A micromagnetic simulation of the dynamics of magnetization switching is performed in exchangecoupled trilayers consisting of two ferromagnetic layers separated by a very thin non-magnetic spacer. The elliptical magnetic thin films with lateral dimensions of 200 nm (long axis) × 100 nm (short axis) and with a total magnetic layer thickness of 4 nm are considered. The spin-flop field and the saturation field obtained under static conditions are found to vary significantly with the thickness asymmetry, but a much smaller dependence is observed in the direct write field. The dynamics of magnetization switching is characterized by an abrupt coherent rotation, followed by oscillations that eventually die out at a pulse duration time of 10 ∼ 20 ns, depending on the magnetization component and the final magnetic state. The coherent rotation occurs at a short pulse duration time of 1 ∼ 2 ns. The oscillations in the two magnetic layers are completely in phase and the frequency estimated from a Fourier analysis is 1.0 GHz. A large difference in the dynamic switching behavior is also observed to exist, depending on the final magnetic state.