Generation of THz-Frequency Electromagnetic Signals in Antiferromagnetic Nano-Oscillators

Existing techniques of the THz-frequency signals generation require complex experimental setups and usually can not be realized even at micron scale. In contrast to this recently it was shown that a thin antiferromagnetic (AFM) layer covered by a thin metal layer having a strong spin-orbital coupling and biased by a dc current can be used as a nano-scale source of electromagnetic ac signals with frequencies close to the eigenfrequencies of AFM material (typically 0.1-10 THz). In this paper we theoretically analyze and compare performance of such THz-frequency sources based on three different mechanisms of ac signal power extraction realized via the inverse spin Hall effect, magnetic dipole emission and via THz-frequency variations of the tunneling anisotropic magnetoresistance in AFM tunnel junction. Our calculations show that the second mechanism (magnetic dipole emission) could be preferable and could provide an output ac power about several microwatts in the frequency range 0.5-2 THz.