  We investigate spin transport through metallic antiferromagnets using
measurements based on spin pumping combined with inverse spin Hall effects in
Ni80Fe20/FeMn/W trilayers. The relatively large magnitude and opposite sign of
spin Hall effects in W compared to FeMn enable an unambiguous detection of spin
currents transmitted through the entire FeMn layer thickness. Using this
approach we can detect two distinctively different spin transport regimes,
which we associate with electronic and magnonic spin currents respectively. The
latter can extend to relatively large distances (up to 9 nm) and is enhanced
when the antiferromagnetic ordering temperature is close to the measurement
temperature.
