Quantifying spin-orbital-to-charge conversion efficiency is crucial for spin-orbitronics. Two widely used methods for determining these efficiencies are based on ferromagnetic resonance (FMR): spin-pumping FMR for the inverse effect, and spin-torque FMR for the direct effect. A key parameter to achieve accurate quantification, especially for spin-pumping FMR, is the rf field strength, $h_{\mathrm{rf}}$. We present a comprehensive theoretical model and experimental protocol that allow a correct quantification of $h_{\mathrm{rf}}$. It was validated by extensive experimental results and it was rigorously tested across various antenna geometries and ferromagnetic systems. We demonstrate that odd symmetric Lorentzian voltages—which perfectly mimic spin-pumping or spin-torque FMR signals—can arise purely from rectification effects (due to anisotropic magnetoresistance) when $h_{\mathrm{rf}}$ orientation is parallel to the ferromagnetic surface. Through a systematic study of various 10-nm-thick ferromagnetic layers, such as $\mathrm{Ni}$, $\mathrm{Ni}\mathrm{Fe}$, $\mathrm{Fe}$, and $\mathrm{Co}\mathrm{Fe}\mathrm{B}$, we find that, while $\mathrm{Fe}$ and $\mathrm{Co}\mathrm{Fe}\mathrm{B}$ exhibit minimal rectification, $\mathrm{Ni}$ and $\mathrm{Ni}\mathrm{Fe}$ generate strong rectified signals that must be corrected. We further demonstrate that these rectification effects become negligible for ferromagnetic thicknesses $\le 6$ nm, as validated in $\mathrm{Ni}\mathrm{Fe}$/$\mathrm{Pt}$ bilayers, providing an important guideline for the design of future heterostructures.

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• Metrology
• Spin Hall effect
• Spin orbitronics
• Spin pumping
• Spin torque
• Ferromagnets
• Magnetic thin films
• Ferromagnetic resonance