Local Ligand-Framework Evolution Prior to Long-Range Antiferromagnetic Ordering in NiPS3

Abstract

Two-dimensional van der Waals antiferromagnets have emerged as a promising platform for low-dimensional spintronics. NiPS3 is a representative system because of its negligible stray fields and ultrafast spin dynamics. However, the relationship between local structural evolution and the establishment of long-range antiferromagnetic order remains incompletely understood. Here, we investigate the temperature-dependent magnetostructural evolution of NiPS3 using anisotropic magnetization measurements, neutron powder diffraction, variable-temperature powder X-ray diffraction Rietveld refinement, Raman spectroscopy, and maximum entropy method electron density reconstruction. Anisotropic magnetization and its temperature derivatives reveal a broad, orientation-dependent magnetic response over approximately 157–164 K. Neutron diffraction detects additional intensity near the magnetic (010) reflection at 150 K, whereas no comparable magnetic Bragg feature is resolved at 160 or 166 K under the present measurement conditions, indicating that the higher-temperature magnetic response is not accompanied by resolvable long-range magnetic Bragg scattering. Structural refinements, Raman spectroscopy, and electron density analyses further identify complementary local structural, vibrational, and electronic responses within the 162–164 K portion of this broad magnetic response interval. Together, these results place the local structural response within the upper part of the magnetic-response interval and before the development of resolvable long-range antiferromagnetic order at lower temperatures. These findings provide an experimental framework for examining magnetostructural evolution and ligand-mediated tuning of magnetism in layered antiferromagnets.