Giant Enhancement of Multi‐Directional Spin Generation in Heavy Metals by Alloying

Spin currents of both out‐of‐plane and transverse spins ( z and y spins) have great potential for energy‐efficient all‐electrical switching of perpendicular magnetization. Here, we demonstrate that alloying Pt with Cu considerably enhances the spin‐orbit torques of both z and y spins in magnetic devices with broken electric symmetry. The damping‐like spin‐orbit torque efficiency of the Pt 1‐ x Cu x /FeCoB alloys varies non‐monotonically with the Pt 1‐ x Cu x composition, with an enhancement of up to 5 times for both the z and y spins relative to that of the conventional Pt/FeCoB. The giant spin‐orbit torque enhancement is attributed to the increased electron scattering induced by alloying and a robust spin Hall conductivity of the Pt 1‐ x Cu x in the Pt‐rich regime. We also demonstrate that Pt 1‐ x Cu x enables 100% magnetic‐field‐free switching of a perpendicularly magnetized FeCoB layer at a current density of 1.8 × 10 7 A/cm 2 , which is the lowest among those for the complete field‐free switching of CMOS integration‐friendly spin‐orbit torque devices. This work has established Pt 1‐ x Cu x as a compelling, efficient multidirectional polarization spin current generator for spintronic memory and computing chip applications.