Shaping the Energy Landscape: Advances in Spin Hall Oscillators

Creating new pathways to achieve faster and more energy efficient ways to store, process, and transfer information is both a challenging and exciting undertaking. Spin Hall oscillators (SHOs) are nanoscale sources of electrically tunable microwave radiation that operate far from equilibrium and whose dynamics are inherently nonlinear. These properties make SHOs attractive for applications such as neuromorphic computing, microwave assisted magnetic recording, and wireless communication. In this talk, we will present how we can shape the magnetic energy landscape of nanowire based SHOs to enhance their performance. We will present a new type of SHO engineered to have easy-magnetic-plane oriented normal to the film plane, enabling large-amplitude spin Hall driven dynamics. While many ferromagnets exhibit natural easy-plane anisotropy in the film plane, the spin Hall current in a heavy metal/ferromagnet bilayer is polarized in this plane and thus cannot drive large-amplitude dynamics. We demonstrate that an artificial easy-plane anisotropy can be achieved by tuning shape and perpendicular magnetic anisotropies in a simple-to-fabricate SHO nanowire, leading to significantly enhanced microwave emission.