Symmetry-dependent field-free switching of perpendicular magnetization

Modern magnetic-memory technology requires all-electric control of perpendicular magnetization with low energy consumption. While spin-orbit torque (SOT) in heavy metal/ferromagnet (HM/FM) heterostructures 1-5 holds promise for applications in magnetic random access memory, till today, it is limited to the in-plane direction. Such in-plane torque can switch perpendicular magnetization only deterministically with the help of additional symmetry breaking, e.g., through the application of an external magnetic field 2,4 , an interlayer coupling 6-9 or an asymmetric design 10-14. Instead, an outof-plane spin-orbit torque 15 could directly switch perpendicular magnetization.