RF-assisted spin torque switching of perpendicular magnetic tunnel junctions

Spin transfer torque switching in nanoscale magnetic tunnel junctions (MTJs) is the basis of spin transfer torque magnetic random access memory (STT-MRAM) technology. However, high write current densities in conventional STT-MRAM devices limit their energy efficiency and durability. Alternative approaches capable of reducing the write current density are needed for the next generation of STT-MRAM. Here, we study current-induced switching of nanoscale MTJs with perpendicular magnetic anisotropy assisted by radio frequency (RF) current. In this STT-MRAM writing protocol, a direct current (DC) pulse is preceded by an RF current pulse. Our measurements reveal that the addition of the RF pulse increases the MTJ switching probability, and that the efficiency of this process increases with decreasing RF frequency. We demonstrate that the RF+DC protocol allows us to decrease the maximum writing current density without sacrificing energy efficiency, which improves device durability. To understand the origin of the observed RF-assisted switching, we compare our experimental results to macrospin and micromagnetic simulations.