  We use ferromagnetic resonance to study the current-induced torques in
YIG/heavy metal bilayers. YIG samples with thickness varying from 14.8 nm to 80
nm, with Pt or Ta thin film on top, are measured by applying a microwave
current into the heavy metals and measuring the longitudinal DC voltage
generated by both spin rectification and spin pumping. From a symmetry analysis
of the FMR lineshape and its dependence on YIG thickness, we deduce that the
Oersted field dominates over spin-transfer torque in driving magnetization
dynamics.
