Spintronic terahertz-frequency nonlinear emitter based on the canted antiferromagnet-platinum bilayers

In this paper, we propose an approximate nonlinear theory of a spintronic terahertz-frequency emitter based on canted antiferromagnet-platinum bilayers. We present a model accounting for the excitation of nonlinear oscillations of the Néel vector in an antiferromagnet using terahertz pulses of an electromagnetic field. We determine that, with increasing amplitude of the pumping pulse, the spin system’s response increases nonlinearly in the fundamental quasiantiferromagnetic mode. We demonstrate control of the Néel vector trajectory by changing the terahertz pulse peak amplitude and frequency and determine the bands of nonlinear excitation using Fourier spectra. Finally, we develop an averaging method which gives the envelope function of an oscillating output electromagnetic field. The nonlinear dynamics of the antiferromagnet-based emitters discussed here is of importance in terahertz-frequency spintronic technologies.