Role of Micromagnetic States on Spin-Orbit Torque-Switching Schemes

Three-terminal spintronic memory devices based on the controlled manipulation of the proximate magnetization of a magnetic nanoelement using spin-orbit torques (SOTs) have attracted growing interest recently. These devices are nonvolatile, can operate at high speeds with low error rates, and have essentially infinite endurance, making them promising candidates for high-speed cache memory. Typically, the magnetization and spin polarization in these devices are collinear to one another, leading to a finite incubation time associated with the switching process. While switching can also be achieved when the magnetization easy axis and spin polarization are noncollinear, this requires the application of an external magnetic field for deterministic switching. Here, we demonstrate a novel SOT scheme that exploits non-uniform micromagnetic states to achieve deterministic switching when the spin polarization and magnetic moment axis are noncollinear to one another in the absence of external magnetic field. We also explore the use of a highly efficient SOT generator, oxygen-doped tungsten in the three-terminal device geometry, confirming its -50% spin Hall angle. Lastly, we illustrate how this scheme may potentially be useful for nanomagnetic logic applications.