  Antiferromagnetic insulators can become active spintronics components by
controlling and detecting their dynamics via spin currents in adjacent metals.
This cross-talk occurs via spin-transfer and spin-pumping, phenomena that have
been predicted to be as strong in antiferromagnets as in ferromagnets. Here, we
demonstrate that a temperature gradient drives a significant heat flow from
magnons in antiferromagnetic insulators to electrons in adjacent normal metals.
The same coefficients as in the spin-transfer and spin-pumping processes also
determine the thermal conductance. However, in contrast to ferromagnets, the
heat is not transferred via a spin Seebeck effect which is absent in
antiferromagnetic insulator-normal metal systems. Instead, the heat is
transferred via a large staggered spin Seebeck effect.
