Spin-Orbit-Torque Switching in 20-nm Perpendicular Magnetic Tunnel Junctions

Magnetization switching utilizing the spin-orbit torque of heavy metals is a promising alternative to spin-transfer torque for a faster and more energy-efficient write mechanism for magnetic random-access memory. We report spin-orbit-torque switching in 20-nm-diameter Co20Fe60B20-MgO-based perpendicular magnetic tunnel junctions with a thermal stability factor of ∼47. Conductive atomic force microscopy was used to measure the tunnel magnetoresistance before and after current pulses through the heavy metal underlayer, and magnetostatic shifts in the minor loops provided evidence of spin-orbit-torque switching. Comparison of estimated critical current densities and write energies suggests that spin-orbit torque can be used as an effective switching mechanism for small and thermally stable perpendicular magnetic tunnel junctions.