Field-Free Perpendicular Magnetic Memory Driven by Out-of-Plane Spin-Orbit Torques

Magnetic memory based on spin-orbit torque (SOT) is a promising candidate for the next-generation storage devices. Materials that generate out-of-plane spin polarization (σ_z) are highly desired and actively pursued as the SOT generator, due to its ability to achieve field-free SOT switching of perpendicular magnetization. However, integrating σ_z into perpendicular magnetic tunnel junction for efficient data writing is not realized. Here, utilizing σ_z from antiferromagnetic spin Hall effect in Mn₂Au, σ_z-enabled field-free SOT switching of perpendicular magnetic tunnel junctions is realized demonstrating a magnetic memory with both writing and reading electrically. The tunnel magnetoresistance ratio achieves 66% with a critical current density of 5.6 × 10⁶ A cm⁻² at room temperature. Such field-free fully SOT switching is further directly confirmed by domain imaging via magneto-optical Kerr effect microscopy. In addition to enabling field-free switching, σ_z is proposed to assist ultrafast and more efficient switching of perpendicular magnetization compared with conventional in-planes ones, based on simulations. This research advances the application of out-of-plane SOTs and paves the way for high-density, high-speed, and low-power magnetic memory.