Energy-Efficient Single Layer Spin Hall Nano-Oscillators Driven by Berry Curvature

Spin Hall nano-oscillators (SHNOs) are emerging spintronic oscillators with significant potential for technological applications, including microwave signal generation, and unconventional computing. Despite their promising applications, SHNOs face various challenges, such as high energy consumption and difficulties in growing high-quality thin film heterostructures with clean interfaces. Here, single-layer topological magnetic Weyl semimetals open a possible solution as they possess both intrinsic ferromagnetism and a large spin-orbit coupling due to their topological properties. However, producing such high-quality thin films of magnetic Weyl semimetals that retain their topological properties and Berry curvature remains a challenge. We address these issues with high-quality single-layer epitaxial ferromagnetic Co₂MnGa Weyl semimetal thin film-based SHNOs. We observe a giant spin Hall conductivity, σ_SHC = (6.08 ± 0.02) × 10⁵ (ℏ/2e) Ω^-1 m^-1, which is an order of magnitude higher than previous reports. Theoretical calculations corroborate the experimental results with a large intrinsic spin Hall conductivity due to presence of a strong Berry curvature. Further, self spin-orbit torque driven magnetization auto-oscillations are demonstrated for the first time, at an ultralow threshold current density of J_th = 6.2 × 10¹¹ A m^-2. These findings indicate that magnetic Weyl semimetals have tremendous application potential for developing energy-efficient spintronic devices.