Gilbert damping in the layered antiferromagnet CrCl3

Abstract

We theoretically and experimentally studied the Gilbert damping evolution of both acoustic and optical magnetic resonance modes in the layered flake CrCl3 with an external magnetic field H applied in plane. Based on a Lagrangian equation and a Rayleigh dissipation function, we predicted that the resonance linewidth ΔH as a function of microwave frequency ω is nonlinear for both acoustic and optical modes in the CrCl3 flake, which is significantly different from the linear relationship of ΔH ∝ ω in ferromagnets. Measuring the microwave transmission through the CrCl3 flake, we obtained the ω–H dispersion and damping evolution ΔH–ω for both acoustic and optical modes. Combining both our theoretical prediction and experimental observations, we concluded that the nonlinear damping evolution ΔH–ω is a consequence of the interlayer interaction during the antiferromagnetic resonance, and the interlayer Gilbert dissipation plays an important role in the nonlinear damping evolution because of the asymmetry of the non-collinear magnetizaiton between layers.