Spin Hall conductivity of polycrystalline TaAs thin films grown by molecular beam epitaxy

We report the synthesis and characterization of polycrystalline TaAs thin films grown by molecular beam epitaxy. We used transmission electron microscopy, energy-dispersive X-ray spectroscopy and reflection high energy electron diffraction to confirm the polycrystallinity and composition of our films. Furthermore, we combined them with a soft ferromagnet (NiFe) and used spin torque ferromagnetic resonance (ST-FMR) to study the charge to spin conversion in the heterostructure. We performed electrical transport measurements and experimentally determined the spin Hall conductivity of polycrystalline TaAs in the thin film regime. Finally, we compare our results with the charge to spin conversion produced by the spin Hall effect in a NiFe/Ta control sample.