Switching-probability distribution of spin-torque switching in MgO-based magnetic tunnel junctions

The time-evolution of the switching characteristics of spin-torque switching in MgO-based magnetic tunnel junctions (MTJs) during more than 10 9 write/read cycles was measured experimentally. In the measurements, the magnetic field and current conditions were chosen to give a switching probability ( P sw ) of about 0.5, where P sw is most sensitive to changes in the magnetic properties of an MTJ cell. Interestingly, some MTJ cells showed small jumps of P sw , which can be attributed to random transitions between states with slightly different magnetic configurations. Such time-evolution measurement can be used to evaluate the stability of the switching characteristics of memory cells.