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arXiv · 2606.10498

Microscopic evidence for a Zhang-Rice triplet state in the van der Waals antiferromagnet, NiPS$_3$

Beom Hyun Kim·Youjin Lee·Junik Hwang·Junghyun Kim·Je-Geun Park·Seung-Ho Baek
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Abstract

Quantum-entangled states underpin many emergent phenomena in quantum materials, yet their direct experimental identification remains a challenge. NiPS$_3$, a van der Waals antiferromagnet exhibiting a resolution-limited magnetic exciton in its ordered phase, has been proposed to host a many-body entangled Zhang-Rice triplet state. Here, using $^{33}$S nuclear magnetic resonance (NMR) on $^{33}$S-enriched NiPS$_3$ single crystals, we provide microscopic evidence for this charge-transfer state. The $^{33}$S and $^{31}$P Knight shifts as a function of temperature reveal a unified spin-triplet configuration arising from strong hybridization between a self-doped hole in the S $3p$ orbitals and a hole in Ni $3d$ orbitals. Furthermore, the $^{33}$S nuclear spin-lattice relaxation rate exhibits a power-law divergence as it approaches the N\'eel temperature $T_N=155$ K, indicating critical slowing down of collective charge fluctuations consistent with spin-nematic correlations. These results reveal a spin-charge-intertwined ground state and establish the microscopic foundation for the exceptional coherence of the magnetic exciton in NiPS$_3$.

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Beom Hyun Kim, Youjin Lee, Junik Hwang, Junghyun Kim, Je-Geun Park, Seung-Ho Baek. 2026-06-09. Microscopic evidence for a Zhang-Rice triplet state in the van der Waals antiferromagnet, NiPS$_3$. https://doi.org/10.1103/hhtt-ffgg

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