Uniform and Robust Field-Free Spin-Orbit Torque Switching via Complementary Double-Wedge Structure.

Field-free spin-orbit torque (SOT) switching of perpendicular magnetization is crucial for next-generation magnetic storage chips. However, achieving robust, uniform, and CMOS-compatible field-free SOT switching remains a significant challenge for industrial applications. Here, a robust field-free switching scheme is proposed based on a complementary double-wedge structure with tilted magnetic anisotropy induced by the tilted Pt(111) texture, yielding a remarkable z/y effective field ratio of 89.8%. Uniform performance is obtained across 2 in. wafers for key metrics─anomalous Hall resistance, switching current density, SOT equivalent field, and field-free switching ratio. Notably, the field-free switching is maintained after annealing, confirming its compatibility with CMOS back-end-of-line processes. In addition to ensuring robust field-free switching, the complementary double-wedge design offers superior uniformity compared to the traditional single-wedge structure, making it highly suitable for mass production.