  A combination of novel technological and fundamental physics prospects has
sparked a huge interest in pure spin transport in magnets, starting with
ferromagnets and spreading to antiferro- and ferrimagnets. We present a
theoretical study of spin transport across a ferrimagnet$|$non-magnetic
conductor interface, when a magnetic eigenmode is driven into a coherent state.
The obtained spin current expression includes intra- as well as
cross-sublattice terms, both of which are essential for a quantitative
understanding of spin-pumping. The dc current is found to be sensitive to the
asymmetry in interfacial coupling between the two sublattice magnetizations and
the mobile electrons, especially for antiferromagnets. We further find that the
concomitant shot noise provides a useful tool for probing the quasiparticle
spin and interfacial coupling.
