We investigate the dependence of the switching process on the perpendicular magnetic anisotropy (PMA) constant in perpendicular spin transfer torque magnetic tunnel junctions (P-MTJs) using micromagnetic simulations. It is found that the final stable states of the magnetization distribution of the free layer after switching can be divided into three different states based on different PMA constants: vortex, uniform, and steady. Different magnetic states can be attributed to a trade-off among demagnetization, exchange, and PMA energies. The generation of the vortex state is also related to the non-uniform stray field from the polarizer, and the final stable magnetization is sensitive to the PMA constant. The vortex and uniform states have different switching processes, and the switching time of the vortex state is longer than that of the uniform state due to hindrance by the vortex.

We investigate the dependence of the vortex formation process on the perpendicular magnetic anisotropy (PMA) constant in a perpendicular magnetic tunnel junction using micromagnetic simulations. Based on the different precession trajectories of magnetic moments, the formation process of a vortex can be divided into two different models: the first includes horizontal precession and damped oscillation, and the second includes damped oscillation only. The time of vortex formation has a nonmonotonic relationship with the PMA constant. By analyzing the variation trend of energies within the system, the underlying physical mechanism of the dependence of the vortex formation process on PMA constant is revealed.