Reduction Of Switching Current Distribution In Spin Transfer Magnetic Random Access Memories

In this paper, the switching current distribution by spin transfer torque is investigated for CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs). The distribution of the spin transfer switching current for a MTJ with junction size of 85x110 nm(2) is 16% when the duration of applied pulse current is 5 ms. In the case of magnetization reversal with magnetic field induced by current with 5 ms pulse duration, the distribution of the switching field is 8.3%. According to our micromagnetic simulation, it is found that the spin transfer current switching seems to exhibit a nonuniform magnetization reversal process, whereas the magnetization switching by the magnetic field exhibits a uniform magnetization reversal process. This leads to the broader distribution related to the repeatability.