Field‐Free Spin‐Orbit Torque Switching of Perpendicular Magnetization by Making Full Use of Spin Hall Effect

Abstract Field‐free switching is a critical issue for spin‐orbit torque‐induced magnetic random‐access memory (SOT‐MRAM) with perpendicular magnetic anisotropic (PMA) towards application. If only the spin‐polarized electrons along the y‐direction (σ_y) are used, deterministic switching cannot be achieved, as the electron polarization direction and easy magnetization direction are orthogonal. In this work, z‐direction polarized electrons (σ_z) produced by the spin Hall effect are utilized to provide the switching direction and σ_y provides the propulsion of magnetic reorientation. With the cooperation of σ_y and σ_z by the spin Hall effect, field‐free switching is achieved. To combine with magnetic tunnel junction (MTJ), a model is proposed, in which heavy metals providing σ_z are deposited on MTJ with asymmetric writing line widths. This model retains the characteristics of read‐write separation and realizes deterministic switching based on SOT.