  The spin-pumping mechanism is probed through a tunnelling MgO interlayer in
Fe/Pt bilayers. We show by ferromagnetic resonance technique and spin-pumping
experiments that spin currents can tunnel through the MgO interlayer for
thickness up to 2~{nm} and can produce significant voltages in the Pt layer.
The electrical detection of spin-pumping furthermore reveals the critical role
of rectification and shunting effects on the generated voltages. The non zero
spin current transport through a few monolayers of an insulating interlayer
might initiate further studies on the role of very thin oxides in spin-pumping
experiments.
