Current Induced Field-Free Switching in a Magnetic Insulator with Enhanced Spin-Orbit Torque

The energy-efficient spin-orbit torque (SOT) based devices are essential for future memory and logic technologies. To realize a deterministic switching, an external in-plane magnetic field is usually needed to break the symmetry, which becomes an obstacle for device applications. Here, a field-free switching in a perpendicularly magnetized yttrium iron garnet covered with an oblique deposited Pt with nitrogen incorporation is demonstrated. The spin-orbit torque efficiency is enhanced with the increasing incorporation ratio of nitrogen in Pt. The maximum effective spin Hall angle of Pt(N) can reach 0.113, which is almost two times larger than that of pure Pt in Pt/YIG. Meanwhile, the switching current density is reduced with the incorporation of nitrogen. These findings open a route toward high-efficiency SOT driven spintronic devices based on magnetic insulators. Enhanced spin-orbit torque efficiency is demonstrated by increasing the incorporation ratio of nitrogen in Pt. The maximum effective spin Hall angle of Pt(N) is almost two times larger than that of pure Pt. In addition, the field-free magnetization switching is also achieved due to the oblique deposition of Pt(N) on the perpendicular magnetized YIG.2 image