Electric-field-induced generation of spin waves in antiferromagnetic films with voltage-controlled magnetic anisotropy

Heterostructures that involve contacting magnetic and dielectric layers may possess a voltage-controlled magnetic anisotropy (VCMA) of interfacial origin. In such heterostructures, spin dynamics can be excited by an electric field created in the dielectric layer, which provides an opportunity for the development of energy-efficient spintronic and magnonic devices. Here, we theoretically describe the generation of spin waves by an electric-field-induced modulation of the interfacial magnetic anisotropy in antiferromagnet-dielectric bilayers. Our approach is based on atomistic simulations of VCMA-driven spin reorientations, which are performed for the (001)-oriented FeRh and ${\mathrm{Mn}}_{2}\mathrm{Au}$ films. It is shown that the sinusoidal variation of VCMA gives rise to the steady precession of spins adjacent to the interface, which induces either evanescent or propagating monochromatic spin waves in the antiferromagnetic film. The amplitude of the generated spin wave strongly depends on the frequency of VCMA oscillations, being maximal at about 33 GHz in the FeRh film and 0.9 THz in the ${\mathrm{Mn}}_{2}\mathrm{Au}$ one. The analysis of simulation data enables us to determine dispersion relations of the propagating spin waves and their decay lengths. Importantly, antiferromagnetic magnons with high frequencies \ensuremath{\sim}100 GHz and large decay lengths \ensuremath{\sim}300 nm can be excited in the FeRh/MgO bilayers. Our findings show that the antiferromagnet-dielectric heterostructures possessing VCMA provide the opportunity for an energy-efficient electrical generation of high-frequency spin waves.