AI 中文总结
研究结合不同磁各向异性的VI3材料，用基于第一性原理计算的原子自旋动力学模拟，从单离子各向异性和交换相互作用角度研究临界温度行为，揭示其对V原子比例的敏感性及相关机制。
AI 中文摘要
在磁性范德华材料中，三卤化钒家族有独特特性。特别是VI3含两种不同类型V原子，其磁各向异性差异显著。通过第一性原理计算的原子自旋动力学模拟，研究单离子各向异性和交换相互作用对临界温度行为的影响，揭示V原子不均匀性及两种V构型共存对磁有序的作用。
英文摘要
Among magnetic van der Waals materials, the vanadium trihalide family exhibits unique features. In particular, VI3 contains V atoms of two different types, as two energetically close electronic occupations can coexist in real samples. These types show strikingly different magnetic anisotropy, predicted to differ by more than an order of magnitude. The combination forms a distinctive magnetic system. VI3 also displays an unusual thickness dependence: the monolayer Curie temperature (TC) is higher than that of the bulk, contrary to the expectation that interlayer coupling reinforces magnetic order. Using atomistic spin-dynamics simulations informed by first-principles calculations, we investigate the critical temperature behavior from the combined perspective of single-ion anisotropy and exchange interactions. The strong anisotropy contrast significantly affects thermal stability: increasing the fraction of high-anisotropy sites raises the energy cost of transverse spin fluctuations and increases the ordering temperature. Furthermore, V-atom inhomogeneity makes the interlayer super-superexchange network spatially nonuniform, creating competing exchange pathways. This weakens coherent interlayer order while preserving robust intralayer ferromagnetic correlations, thus modifying the bulk-monolayer TC relation. Our model reproduces experimental TC values when the ratio of the two V types is close to 1:1, in agreement with two experimental methods. This supports the coexistence of two V configurations in VI3. The monolayer TC is reproduced with a slightly modified ratio, possibly linked to polaron concentration. The sensitivity of TC to this ratio suggests that the ordering temperature of VI3 can in principle be tuned over a broad range by controlling the relative occupation of the two vanadium configurations.
