We use spin torque ferromagnetic resonance and ferromagnetic-resonance-driven spin pumping to detect spin-charge interconversion at room temperature in heterostructure devices that interface an archetypal Dirac semimetal, ${\mathrm{Cd}}_3{\mathrm{As}}_2$, with a metallic ferromagnet, ${\mathrm{Ni}}_{0.80}{\mathrm{Fe}}_{0.20}$ (permalloy). Angle-resolved photoemission directly reveals the Dirac-semimetal nature of the samples prior to device fabrication and high-resolution transmission electron microscopy is used to characterize the crystalline structure and the relevant heterointerfaces. We find that the spin-charge interconversion efficiency in ${\mathrm{Cd}}_3{\mathrm{As}}_2/$permalloy heterostructures is comparable to that in heavy metals and that it is enhanced by the presence of an interfacial oxide. Spin torque ferromagnetic resonance measurements reveal an in-plane spin polarization regardless of an oxidized or pristine interface. We discuss the underlying mechanisms for spin-charge interconversion by comparing our results with first principles calculations and conclude that extrinsic mechanisms dominate the observed phenomena. Our results indicate a need for caution in interpretations of spin-transport and spin-charge conversion experiments in ${\mathrm{Cd}}_3{\mathrm{As}}_2$ devices that seek to invoke the role of topological Dirac and Fermi arc states.

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• Spin pumping
• Spin transfer torque
• Surface & interfacial phenomena
• Surface states
• Topological materials
• Dirac semimetal
• Magnetic multilayers
• Ferromagnetic resonance