External‐Field‐Free Spin Hall Switching of Perpendicular Magnetic Nanopillar with a Dipole‐Coupled Composite Structure

Abstract

Abstract Spin Hall effect (SHE)‐induced reversal of perpendicular magnetization has attracted significant interest, due to its potential for low‐power memory and logic devices. However, the switching requires an assisted in‐plane magnetic field, which hampers its practical applications. Here, a new approach for external‐field‐free spin Hall switching of a perpendicular nanomagnet is introduced. This approach utilizes a local dipolar field arising from an in‐plane biasing layer to assist the switching. Robust switching of a 285 × 95 nm 2 perpendicular CoFeB nanomagnet is demonstrated in the absence of any external magnetic field. Micromagnetic simulation is performed to illustrate the magnetic dynamics of the switching process. Large in‐plane compensation field of 135 Oe is obtained in the composite nanodevices, reflecting a strong symmetry‐breaking behavior. Compared with other proposed methods for external‐field‐free spin Hall switching, the dipole‐coupled composite structure is compatible with a wide range of spin Hall systems and perpendicular magnetic tunnel junctions, paving a way towards practical spin–orbit torque‐based memory and logic applications.