Spin Pumping and Inverse Spin Hall Voltages from Dynamical Antiferromagnets

Dynamical antiferromagnets pump spins efficiently into adjacent conductors as ferromagnets. The high antiferromagnetic resonance frequencies represent a challenge for experimental detection, but magnetic fields can reduce these resonance frequencies. We compute the inverse spin Hall voltages resulting from dynamical spin excitations as a function of a magnetic field along the easy axis and the polarization of the driving AC magnetic field perpendicular to the easy axis. We consider the insulating antiferromagnets MnF$_2$, FeF$_2$, and NiO. Near the spin-flop transition, there is a significant enhancement of the DC spin pumping and inverse spin Hall voltage for the uniaxial antiferromagnets MnF$_2$ and FeF$_2$. In the biaxial NiO, the voltages are much weaker, and there is no spin-flop enhancement of the DC component.