Tunable magnons in a dual-gated 2D antiferromagnet

The layered antiferromagnet CrSBr features magnons coupled to other quasiparticles, including excitons and polaritons, enabling their easy optical accessibility. In this work, we investigate the tunability of magnons in few-layered devices in response to changes in carrier density and the application of a perpendicular electric field. We demonstrate an on-chip tunability of the in- and out-of-phase magnon frequencies by up to 2 GHz. While the frequencies of both modes increase with the electron density, we observe an asymmetric response with respect to the electric field in a dual-gated trilayer device. To understand the mechanism of this disparity, we develop a layer-resolved macrospin model describing the magnetic dynamics in thin, non-uniformly doped devices. Through this model we establish the doping- and electric-field-dependence of the exchange interaction, magnetic anisotropy, and magnetic moment of individual layers. Our results advance the applications of gate-tunable magnonic devices based on 2D materials.