Anisotropic Gigahertz Antiferromagnetic Resonances of the Easy-Axis van der Waals Antiferromagnet CrSBr

TL;DR

This study investigates gigahertz-frequency antiferromagnetic resonances in the van der Waals antiferromagnet CrSBr, revealing rich dynamical modes and quantifying magnetic parameters through experimental measurements and modeling.

Contribution

It provides the first detailed measurement and modeling of antiferromagnetic resonances in CrSBr, including quantification of exchange and anisotropy fields.

Findings

Resonance frequencies depend on magnetic field magnitude and angle.

Good agreement with Landau-Lifshitz model for two sublattices.

Quantified interlayer exchange and anisotropy parameters.

Abstract

We report measurements of antiferromagnetic resonances in the van der Waals easy-axis antiferromagnet CrSBr. The interlayer exchange field and magnetocrystalline anisotropy fields are comparable to laboratory magnetic fields, allowing a rich variety of gigahertz-frequency dynamical modes to be accessed. By mapping the resonance frequencies as a function of the magnitude and angle of applied magnetic field we identify the different regimes of antiferromagnetic dynamics. The spectra show good agreement with a Landau-Lifshitz model for two antiferromagnetically-coupled sublattices, accounting for inter-layer exchange and triaxial magnetic anisotropy. Fits allow us to quantify the parameters governing the magnetic dynamics: at 5 K, the interlayer exchange field is $\mu_0 H_E =$ 0.395(2) T, and the hard and intermediate-axis anisotropy parameters are $\mu_0 H_c =$ 1.30(2) T and $\mu_0 H_a =$ 0.383(7) T. The existence of within-plane anisotropy makes it possible to control the degree of hybridization between the antiferromagnetic resonances using an in-plane magnetic field.