  Spin pumping and spin-transfer torques are two reciprocal phenomena widely
studied in ferromagnetic materials. However, pumping from antiferromagnets and
its relation to current-induced torques have not been explored. By calculating
how electrons scatter off a normal metal-antiferromagnetic interface, we derive
pumped spin and staggered spin currents in terms of the staggered field, the
magnetization, and their rates of change. For both compensated and
uncompensated interfaces, spin pumping is of a similar magnitude as in
ferromagnets with a direction controlled by the polarization of the driving
microwave. The pumped currents are connected to current-induced torques via
Onsager reciprocity relations.
