Complex chalcogenides in the MPS3 family of materials (M = Mn, Fe, Co, and Ni) display remarkably different phase progressions depending upon the metal center orbital filling, character of the P-P linkage, and size of the van der Waals gap. There is also a stacking pattern and spin state difference between the lighter and heavier transition metal-containing systems that places CoPS3 at the nexus of these activities. Despite these unique properties, this compound is under-explored. Here, we bring together Raman scattering spectroscopy and infrared absorption spectroscopy with X-ray techniques to identify a structural component to the 119 K magnetic ordering transition as well as a remarkable lower temperature set of magnon-phonon pairs that engage in avoided crossings along with a magnetic scattering continuum that correlates with phonon lifetime effects. These findings point to strong spin-phonon entanglement as well as opportunities to control these effects under external stimuli.
@article{arxiv.2506.09265,
title = {Spin-lattice entanglement in $\mathbf{CoPS}_3$},
author = {Thuc T. Mai and Amber McCreary and K. F. Garrity and Rebecca L. Dally and Sambridhi Shah and Bryan C. Chakoumakos and Md Nasim Afroj Taj and Jeffrey W. Lynn and Michael A. McGuire and Benjamin S. Conner and Mona Zebarjadi and Janice L. Musfeldt and Angela R. Hight Walker and Rahul Rao and Michael A. Susner},
journal= {arXiv preprint arXiv:2506.09265},
year = {2025}
}