  In antiferromagnetic materials the order parameter exhibits resonant modes at
frequencies that can be in the terahertz range, making them interesting
components for spintronic devices. Here, it is shown that antiferromagnetic
resonance can be excited using the inverse spin-Hall effect in a system
consisting of an antiferromagnetic insulator coupled to a normal-metal
waveguide. The time-dependent interplay between spin-torque, ac
spin-accumulation and magnetic degrees of freedom is studied. It is found that
the dynamics of the antiferromagnet effects the frequency-dependent
conductivity of the normal metal. Further, it is shown that in
antiferromagnetic insulators, the resonant excitation by ac spin-currents can
be orders of magnitude more efficient than excitation by the current-induced
Oersted field.
