Topological spintronics: topological insulators and skyrmions

Abstract: Novel computer architectures bring computing and memory together, whose memory units need to be fast, energy efficient, scalable and nonvolatile. My research concerns innovating new types of magnetic memory or spintronic devices to achieve ultrahigh energy efficiency and ultracompact size by employing quantum materials and heterostructure. The highest energy efficiency of magnetic memory requires the largest charge-to-spin conversion efficiency. We utilize topological surface states of topological insulators (TIs), which have unique spin-momentum locking and thus are 100% spin-polarized, to obtain giant spin-orbit torques, whose magnitudes are more than one order larger than those of traditional heavy metals. We integrate TIs into room temperature magnetic memories for ultralow power dissipation. To acquire the best scaling performance, we investigate emerging topological skyrmions in magnetic thin films, which are arguably the smallest spin texture in nature. Contrast to skyrmions in metallic systems, insulating skyrmions possess lower damping and thus potentially lower power dissipation. We create first room temperature stable skyrmions in heterostructures consisting of heavy metals and magnetic insulators.