  Measurements of switching via spin-orbit coupling (SOC) mechanisms are
discussed for a pair of inverted Pt/Co/Pt stacks with asymmetrical Pt
thicknesses. Taking into account the planar Hall effect contribution, effective
fields of spin-orbit torques (SOT) are evaluated using lock-in measurements of
the first and second harmonics of the Hall voltage. Reversing the stack
structure leads to significant asymmetries in the switching behavior, including
clear evidence of a nonlinear current dependence of the transverse effective
field. Our results demonstrate potentially complex interplay in devices with
all-metallic interfaces utilizing SOT.
