Field‐Free Perpendicular Magnetic Memory Driven by Out‐of‐Plane Spin‐Orbit Torques
Shixuan Liang, Aitian Chen, Lei Han, Hua Bai, Chong Chen, Lin Huang, Mingyuan Ma, Feng Pan, Xixiang Zhang, Cheng Song
Abstract
Abstract 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 Mn 2 Au, 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 × 10 6 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.