Charge-spin correlation and self-doped ground state in van der Waals antiferromagenet NiPS3

Strong spin-charge coupling is found in a layered transition-metal trichalcogenide (TMTC) NiPS3, a van der Waals antiferromagnet, from studies of the electronic structure using several experimentaland theoretical tools: spectroscopic ellipsometry, X-ray absorption and photoemission spectroscopy, and density functional theory. NiPS3 displays an anomalous behavior on the optical spectral weight at the magnetic ordering temperature, reflecting the strong correlation between the electronic and magnetic structure. X-ray absorption and photoemission data support a self-doped ground state in NiPS3, which provides a consistent explanation of the optical spectra. Our work demonstrates that layered transition TMTC magnets are useful candidates for the study of correlated electron physics and two-dimensional magnetism on the same platform.