Quantum magnets admit more than one classical limit and N-level systems with strong single-ion anisotropy are expected to be described by a classical approximation based on SU(N) coherent states. Here we test this hypothesis by modeling finite temperature inelastic neutron scattering (INS) data of the effective spin-one antiferromagnet Ba₂FeSi₂O₇. The measured dynamic structure factor is calculated with a generalized Landau-Lifshitz dynamics for SU(3) spins. Unlike the traditional classical limit based on SU(2) coherent states, the results obtained with classical SU(3) spins are in good agreement with the measured temperature dependent spectrum. The SU(3) approach developed here provides a general framework to understand the broad class of materials comprising weakly coupled antiferromagnetic dimers, trimers, or tetramers, and magnets with strong single-ion anisotropy.

量子磁体允许超过一个经典极限，具有强单离子各向异性的N能级系统有望通过基于 SU( N ) 相干态的经典近似来描述。在这里，我们通过对有效自旋一反铁磁体 Ba ₂ FeSi ₂ O _{7的有限温度非弹性中子散射 (INS) 数据建模来检验这一假设}. 测量的动态结构因子是使用 SU(3) 自旋的广义 Landau-Lifshitz 动力学计算的。与基于 SU(2) 相干态的传统经典极限不同，用经典 SU(3) 自旋获得的结果与测量的温度相关光谱非常一致。这里开发的 SU(3) 方法提供了一个通用框架来理解包括弱耦合反铁磁二聚体、三聚体或四聚体以及具有强单离子各向异性的磁体在内的广泛材料类别。