  We recently reported measurements of spin polarization in W and Pt thin films
produced by the spin Hall effect (SHE) using a magneto-optic Kerr effect (MOKE)
system based on crossed polarizers that detects changes in light intensity.
Riego et al used a generalized magneto-optical ellipsometry system that in
principle can distinguish pure optical reflectivity from magneto-optic signals,
but were unable to detect SHE polarization in their nominally W, Ta and Pt
films. They argued that our results are spurious and likely due to resistive
heating which temporally modulates the film temperature and reflectivity, and
that any SHE polarization is too small to be detected in metal films. In this
comment, we argue that our original results are correct as presented, and
discuss why
