Spin-lattice entanglement in $\mathbf{CoPS}_3$

TL;DR

This study investigates the spin-lattice entanglement in CoPS₃, revealing strong magnon-phonon interactions and magnetic ordering phenomena through combined spectroscopic and X-ray techniques.

Contribution

It provides new insights into the spin-phonon coupling and magnetic properties of CoPS₃, a relatively unexplored member of the $M$PS₃ family.

Findings

Identification of a 119 K magnetic transition linked to structural changes

Observation of magnon-phonon pairs engaging in avoided crossings

Detection of a magnetic scattering continuum correlated with phonon lifetimes

Abstract

Complex chalcogenides in the $M$PS$_3$ 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 CoPS$_3$ 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.