Fig. 3: Simulated spin evolution in 2D antiferromagnetic NiPS₃.

a Schematic of spin evolution under an in-plane magnetic field. The blue, red, and orange arrows represent the spin momenta M₁, M₂, and Néel vector L, with angles φ₁, φ₂, and φ with respect to the positive direction of the applied field (depicted as a black arrow). b Magnetic-field-direction-dependent k values, which are derived from the experimental data using the formula \(k=\Delta E/2{\mu }_{B}B\). The dashed line represents the fitting line based on \(k={g}_{\text{s}}\cos \theta\). Error bars represent standard errors from fitting function. c Simulated k value as a function of the magnitude B and direction θ of the magnetic field. k is defined as \({g}_{s}\Delta {\text{m}}_{\text{s}}\cos \varphi\). d Simulated energy splitting ΔE as a function of the magnitude B and direction θ of the magnetic field. e Magnetic-field-dependent energy splitting extracted from experimental data by \(\Delta E={E}_{X+}-{E}_{X-}\), compared with calculated results. The experimental data of θ = 0^o is compared with calculated data of θ = 2^o.