Robust spin Hall effect in polycrystalline -- thin films: Insights from experiments and kwant modeling
Phys. Rev. Applied 25, 034021 – Published 6 March, 2026
DOI: https://doi.org/10.1103/c5x3-yqf8
Abstract
We investigate the spin Hall effect (SHE) in polycrystalline -- alloy thin films with different concentrations and processing conditions. Spin-torque ferromagnetic resonance and second-harmonic Hall measurements reveal a consistently large spin Hall angle (SHA; 0.2–0.3) in both as-deposited and postannealed films, indicating that the spin Hall response is robust regarding chemical disorder and thermal treatment within experimental uncertainty. To elucidate the microscopic origin of this behavior, we perform tight-binding transport simulations using the kwant package, explicitly separating intrinsic and extrinsic contributions. While intrinsic spin-orbit coupling alone yields a modest spin Hall response, incorporation of extrinsic mechanisms—such as skew and side-jump scattering—substantially increases the SHA to values comparable to experimental observations within realistic scattering ranges. These results highlight the important role of extrinsic scattering in spin current generation in chemically disordered alloys. By combining experiment and theory, we establish -- alloys as a model platform for exploring the disorder-enabled SHE under realistic growth and processing conditions.
