Micromagnetic model of magnetization reversal driven by spin-polarized current in MgO-based magnetic tunnel junctions

This paper describes the theoretical approach to model the magnetization reversal in magnetic tunnel junction with elliptical cross sectional area based on MgO tunnel barrier. The effects of the defects in the shape sample (computed directly by SEM images) and the presence of a pinhole in the tunnel barrier have been studied. The main results are: (i) the presence of the defects changes the coercive field of the free layer and the average value of the magnetostatic coupling with the pinned layer by less than 10%; (ii) the reversal mechanism driven by the magnetic field can be well described by macrospin approximation for all the non-ideal shape simulated; (iii) the reversal driven by spin-polarized current occurs via a nucleation process which is different with respect to the ideal ellipse in existence of a pinhole or defects.