  Intense current pulses are often required to operate microelectronic and
spintronic devices. Notably, strong current pulses have been shown to induce
magnetoresistance changes attributed to domain reorientation in
antiferromagnet/heavy metal bilayers and non-centrosymmetric antiferromagnets.
In such cases, nonmagnetic resistivity changes may dominate over signatures of
antiferromagnetic switching. We report systematic measurements of the
current-induced changes of the transverse and longitudinal resistance of Pt and
Pt/NiO layers deposited on insulating substrates, namely Si/SiO$_2$,
Si/Si$_3$N$_4$, and Al$_2$O$_3$. We identify the range of pulse amplitude and
length that can be used without affecting the resistance and show that it
increases with the device size and thermal diffusivity of the substrate. No
significant difference is observed in the resistive response of Pt and NiO/Pt
devices, thus precluding evidence on the switching of antiferromagnetic domains
in NiO. The variation of the transverse resistance is associated to a
thermally-activated process in Pt that decays following a double exponential
law with characteristic timescales of a few minutes to hours. We use a
Wheatstone bridge model to discriminate between positive and negative
resistance changes, highlighting competing annealing and electromigration
effects. Depending on the training of the devices, the transverse resistance
can either increase or decrease between current pulses. Further, we elucidate
the origin of the nonmonotonic resistance baseline, which we attribute to
training effects combined with the asymmetric distribution of the current.
These results provide insight into the origin of current-induced resistance
changes in metal layers and a guide to minimize nonmagnetic artifacts in
switching experiments of antiferromagnets.
