  We present harmonic transverse voltage measurements of current-induced
thermoelectric and spin-orbit torque (SOT) effects in ferromagnet/normal metal
bilayers, in which thermal gradients produced by Joule heating and SOT coexist
and give rise to ac transverse signals with comparable symmetry and magnitude.
Based on the symmetry and field-dependence of the transverse resistance, we
develop a consistent method to separate thermoelectric and SOT measurements. By
addressing first ferromagnet/light metal bilayers with negligible spin-orbit
coupling, we show that in-plane current injection induces a vertical thermal
gradient whose sign and magnitude are determined by the resistivity difference
and stacking order of the magnetic and nonmagnetic layers. We then study
ferromagnet/heavy metal bilayers with strong spin-orbit coupling, showing that
second harmonic thermoelectric contributions to the transverse voltage may lead
to a significant overestimation of the antidamping SOT. We find that
thermoelectric effects are very strong in Ta(6nm)/Co(2.5nm) and negligible in
Pt(6nm)/Co(2.5nm) bilayers. After including these effects in the analysis of
the transverse voltage, we find that the antidamping SOTs in these bilayers,
after normalization to the magnetization volume, are comparable to those found
in thinner Co layers with perpendicular magnetization, whereas the field-like
SOTs are about an order of magnitude smaller.
