US Patent 9929210 Spin-orbit torque magnetic random access memory

A spin-orbit torque magnetic random access memory includes a substrate, and an SOT memory cell disposed on the substrate and including a magnetic free layer including a ferromagnetic first metal layer, an anti-ferromagnetic second metal layer, and a third metal layer for generating spin-Hall effect. The first metal layer has a thickness ranging from 0.5 nm to 1.5 nm and exhibits perpendicular magnetic anisotropy (PMA). The second metal layer has a thickness greater than 6 nm for providing an exchange bias field. The second metal layer is an IrMn layer not undergone out-of-plane magnetic annealing or coating and exhibiting no PMA. The magnetic free layer has a coercive magnetic field (Hc) upon reaching the critical current density, and |HEB|>|Hc|.