Field-Free Spin–Orbit Torque-Induced Exchange Bias Switching

The ability to electrically control exchange bias (EB) in antiferromagnet/ferromagnet (AFM/FM) heterostructures is crucial for advancing energy-efficient and multifunctional spintronic devices. In this work, we systematically investigate spin–orbit torque (SOT)-induced EB switching in IrMn-based heterostructures. By tuning the sputtering power during IrMn deposition, we achieve precise control of its (111) texture and demonstrate an enhanced exchange bias field (H_ex) exceeding 750 Oe. Detailed IrMn thickness-dependent studies further reveal that the EB saturates beyond 10 nm, consistent with the estimated domain wall width, and the SOT switching of EB is governed primarily by interfacial spin interactions. In patterned pillar devices, we demonstrate 100% deterministic SOT-induced EB switching, overcoming signal degradation in crossbar geometries. Furthermore, by introducing a tilted anisotropy through wedged deposition of the bottom Pt layer, we realize robust, field-free SOT-induced perpendicular EB switching. Our findings provide a pathway toward practical AFM-based spintronic memory with scalable and field-free operation.