THz generation and frequency manipulation in AFM/HM interfaces

Abstract

Abstract In this paper, we propose an approximate nonlinear theory of a spintronic terahertz-frequency oscillator based on antiferromagnet-heavy metal interfaces. We present a model of excitation of nonlinear oscillations of Neel vector in an antiferromagnet under the action of terahertz pulses of an electromagnetic field. We determine that, with increasing pumping pulse amplitude, the spin system response increases nonlinearly in the fundamental quasi-antiferromagnetic mode. Our results theoretically show that a spin-current flowing from a heavy metal due to the spin-Hall effect vary the frequencies of the output EM oscillations in a wide range, which could be detected by a standard pump-and-probe spectroscopy. Our study paves the way to laser-induced, electrically tunable, low-power, ultrafast AFM-based oscillator that operates without external magnetic fields at room temperature for telecommunication systems, bio-inspired networks and optical networks on chip. The nonlinear dynamics of the antiferromagnet-based emitters discussed here is of importance in terahertz-frequency spintronic technologies.