Antiferromagnetic resonance excited by oscillating electric currents

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.