Enhancing z Spin Generation in Trivial Spin Hall Materials for Scalable, Energy-Efficient, Field-Free, Complete Spin-Orbit Torque Switching Applications.

Despite the remarkable efforts in the past two decades, it has remained a major challenge to achieve switching of perpendicularly magnetized spin-orbit torque devices in a scalable, energy-efficient, field-free, integration-friendly, and complete manner. Here, a giant enhancement of z spin generation in low-resistivity spin Hall metal/FeCoB devices is reported by alloying the spin Hall metal Pt with Ti and by electric asymmetry engineering. The damping-like spin torques of z spins and y spins are enhanced by 6 and 3 times relative to those of conventional Pt/FeCoB and enable complete, record-low-power, deterministic switching of FeCoB devices with strong perpendicular magnetic anisotropy and high coercivity. The PtTi/FeCoB heterostructure also exhibits relatively low resistivity, wafer-scale uniform sputterdeposition on silicon oxide, good compatibility with magnetic tunnel junctions, and excellent thermal stability of exceeding 400 °C. These results unambiguously establish the PtTi/FeCoB as the most compelling candidate for solving the bottleneck of scalable, energy-efficient, field-free, integration-friendly, and complete spin-orbit torque switching technologies. This work also provides a universal strategy for developing high-performance generators of z-spin current and will stimulate the exploration of exotic spin currents by alloying "trivial" spin Hall materials.