Oersted Field-Guided Electric Field Switching in Perpendicular Magnetic Free Layer

We study the electric field (EF)-assisted magnetization switching in perpendicular magnetic free layer guided by an Oersted field using micromagnetic simulations. The EF is used to reduce the perpendicular magnetic anisotropy (PMA), and thus change the easy axis from the perpendicular to the in-plane. The Oersted field is used to guide the magnetization to the desired switching directions. The effects of various physical parameters, such as the damping constant, the PMA change, the PMA after EF, the saturation magnetization, and the Oersted field, on the switching times are examined. The simulation results indicate that the switching time decreases with the increase in the damping constant and the Oersted field. The EF efficiency has a significant effect on the switching performance. In order to make a fast and energy-saving switching, the PMA of the free layer needs to be properly controlled. Simulation results also show that a material with higher M-s needs a lower EF efficiency for fast switching. For the merit of a fast switching, large damping constant (alpha > 0.1) should be used. In addition, large damping constant requires a small Oersted field for a reliable switching, which reduces the energy during writing. For alpha = 0.3, a fast total switching time within 3 ns can be achieved with an Oersted field as small as 1 mT.