Evaluation of Spin-Transfer Switching in CoFeB/MgO/CoFeB Magnetic Tunnel Junctions

Current-induced magnetization switching was demonstrated on Co–Fe–B/MgO/Co–Fe–B magnetic tunnel junctions (MTJs), which exhibited giant tunnel magnetoresistance ratios of about 100%. Switching current density at a pulse duration of 100 ms was about 6×10 6 A/cm 2 at room temperature. The switching current density was reduced to one-third of the smallest value for the MgO-based MTJs reported to date. Dependence of the switching current on pulse duration and on the external magnetic field was discussed based on a theoretical model incorporating thermally activated spin-transfer switching. The spin-transfer switching in the MgO-based MTJs realizes low writing power consumption and a high read-out signal in high-density magnetoresistive random access memory.