Tunable magnons in a dual-gated 2D antiferromagnet.

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