Modeling of the spin-transfer torque switching in FePt/MgO-based perpendicular magnetic tunnel junctions: A combined ab initio and micromagnetic simulation study

Combined ab initio and micromagnetic simulations are carried out to build up a direct relationship between critical switching current J_c and geometric structure (in-plane lattice constant a and film thickness) of FePt in magnetic tunnel junctions. Ab initio calculations predict that the strain effect can significantly influence the uniaxial magnetic anisotropy constant K _u, whereas the thickness has less significant impact on K _u. Micromagnetic simulations show that J_c linearly increases with the increasing K_u (the decreasing a) and the switching time decreases with the increasing current at a fixed K_u and is sensitive to the perpendicular spin-torque factor at negative current.