  The spin torque ferromagnetic resonance (STFMR) is one of the popular methods
for measurement of the spin Hall angle (SHA). However, in order to accurately
determine SHA from STFMR measurements, the acquired data must be carefully
analyzed: The resonance linewidth should be determined to an accuracy of a
fraction of an Oe, while the dynamical interaction leading to the measured
response consists of the conventional field-induced ferromagnetic resonance
(FMR), spin-torque induced FMR, and of the inverse spin Hall effect (ISHE).
Additionally, the signal often deteriorates when DC current is passed through
the device. In this work we compare the STFMR method with two other FMR-based
methods that are used to extract SHA. The first is a device-level FMR and the
second is based on the ISHE. We identify artefacts that are caused by the noise
floor of the instrumentation that make the measurement of SHA illusive even
when the signal to noise ratio seems to be reasonable. Additionally, we
estimate a 10% error in SHA that results from neglecting the magnetic
anisotropies as in conventional measurements. Overall, we find the STFMR to be
the most robust of the three methods despite the complexity of the interaction
taking place therein. The conclusions of our work lead to a more accurate
determination of SHA and will assist in the search of novel materials for
energy efficient spin-based applications.
