  Current induced spin-orbit torques (SOTs) in Fe/Pt bilayers have been
investigated utilizing the spin-orbit torque ferromagnetic resonance (SOT-FMR)
measurement. Characterization of thin films with different thicknesses
indicates existence of a sizable field-like spin-orbit torque competing with
the Oersted field induced torque (Oersted torque). The field-like torque is
neglected in the standard SOT-FMR method and the presence of a strong
field-like torque makes estimation of the spin Hall angle (SHA) problematic.
Also, it is challenging to differentiate the field-like torque from the Oersted
torque in a radiofrequency measurement. Based on the thickness dependence of
field-like torque, anti-damping torque, and Oersted torque, the
thickness-dependent SOT-FMR measurement is proposed as a more reliable,
self-calibrated approach for characterization of spin-orbit torques.
