The recently discovered two-dimensional (2D) van der Waals magnet NiPS$_3$ provides a new route to examine many-body quasiparticles under 2D confinement. Excitons are of particular interest due to their strong coupling to the magnetic ground state. Here, by using a first-principles-based approach, we find bright excitons between 1.4 eV to 1.7 eV similar to the coherent exciton experimentally observed. Our analysis shows that each exciton in NiPS$_3$ is composed of a combination of $d$-$d$ and charge-transfer character, where the relative ratio of each pairing configuration changes with exciton energy. Finally, the wave function of the electrons and holes is revealed to be spatial indirect, spanning the zig-zag AFM domain wall, suggesting a microscopic origin of the observed strong magneto-exciton coupling.

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相关范德华反铁磁体中电子空穴对的 $ab~initio$ 研究：NiPS$_3$

最近发现的二维 (2D) 范德华磁体 NiPS$_3$ 提供了一种在二维约束下检查多体准粒子的新途径。激子因其与磁性基态的强耦合而受到特别关注。在这里，通过使用基于第一原理的方法，我们发现明亮的激子在 1.4 eV 到 1.7 eV 之间，类似于实验观察到的相干激子。我们的分析表明，NiPS$_3$ 中的每个激子由 $d$-$d$ 和电荷转移特性的组合组成，其中每个配对配置的相对比率随激子能量而变化。最后，电子和空穴的波函数被揭示为空间间接的，跨越之字形 AFM 畴壁，表明观察到的强磁激子耦合的微观起源。