  Spin pumping in a ferromagnet/nonferromagnet heterostructure is directly
imaged with spatial resolution as well as element selectivity. The
time-resolved detection in scanning transmission x-ray microscopy allows to
directly probe the spatial extent of the ac spin polarization in Co-doped ZnO
which is generated by spin pumping from an adjacent permalloy microstrip.
Comparing the relative phases of the dynamic magnetization component of the two
constituents is possible and found to be antiphase. The correlation between the
distribution of the magnetic excitation in the permalloy and the Co-doped ZnO
reveals that laterally there is no one-to-one correlation. The observed
distribution is rather complex, but integrating over larger areas clearly
demonstrates that the spin polarization in the nonferromagnet extends laterally
beyond the region of the ferromagnetic microstrip. Therefore the observations
are better explained by a local spin pumping efficieny and a lateral
propagation of the ac spin polarization in the nonferromagnet over the range of
a few micrometers.
